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Nephritic Syndrome

Nephritic syndrome is a broad category of glomerular diseases characterized by glomerular hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma, variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables loss of renal function, and hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension. These features are in contrast to those of nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome, which includes glomerular diseases characterized by severe proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children, although there is sometimes overlap of > 1 glomerular disease in the same individual. The clinical presentations of nephritic syndrome are highly varied, from asymptomatic with urinary abnormalities to life-threatening critical illness. Diagnosis is suggested by hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma, mild-to-moderate proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children, and certain serologies (e.g., ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis); kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma is necessary in most cases. Management varies as widely as the clinical presentations, from watchful waiting in mild cases to immunosuppression and plasmapheresis Plasmapheresis Procedure whereby plasma is separated and extracted from anticoagulated whole blood and the red cells retransfused to the donor. Plasmapheresis is also employed for therapeutic use. Stevens-Johnson Syndrome in aggressive disease.

Last updated: 10 Dec, 2021

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

Nephritic syndrome is defined by some or all of the following findings: 

  • Glomerular hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma: active urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat sediment
    • Dysmorphic RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology
    • RBC casts
  • Mild-to-moderate proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children (500–3500 mg/day called “subnephrotic”)
  • Hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension due to:
    • Volume overload/Na retention
    • Suppression Suppression Defense Mechanisms of the RAAS RAAS A blood pressure regulating system of interacting components that include renin; angiotensinogen; angiotensin converting enzyme; angiotensin i; angiotensin ii; and angiotensinase. Renin, an enzyme produced in the kidney, acts on angiotensinogen, an alpha-2 globulin produced by the liver, forming angiotensin I. Angiotensin-converting enzyme, contained in the lung, acts on angiotensin I in the plasma converting it to angiotensin II, an extremely powerful vasoconstrictor. Angiotensin II causes contraction of the arteriolar and renal vascular smooth muscle, leading to retention of salt and water in the kidney and increased arterial blood pressure. In addition, angiotensin II stimulates the release of aldosterone from the adrenal cortex, which in turn also increases salt and water retention in the kidney. Angiotensin-converting enzyme also breaks down bradykinin, a powerful vasodilator and component of the kallikrein-kinin system. Adrenal Hormones
  • Azotemia Azotemia A biochemical abnormality referring to an elevation of blood urea nitrogen and creatinine. Azotemia can be produced by kidney diseases or other extrarenal disorders. When azotemia becomes associated with a constellation of clinical signs, it is termed uremia. Acute Kidney Injury:
    • Elevated BUN
    • BUN-to-creatinine ratio > 15
  • Oliguria Oliguria Decreased urine output that is below the normal range. Oliguria can be defined as urine output of less than or equal to 0. 5 or 1 ml/kg/hr depending on the age. Renal Potassium Regulation: < 500 mL of urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat/day

Etiology

  • Acute glomerulonephritis Acute Glomerulonephritis Nephritic Syndrome in Children (GN; presents with mild-to-moderate AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury):
    • IgA nephropathy IgA nephropathy IgA nephropathy (Berger’s disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy (also chronic)
    • Poststreptococcal GN ( PSGN PSGN Post-streptococcal glomerulonephritis (PSGN) is a type of nephritis that is caused by a prior infection with group A beta-hemolytic Streptococcus (GAS). The clinical presentation of PSGN can range from asymptomatic, microscopic hematuria to full-blown acute nephritic syndrome, which is characterized by red-to-brown urine, proteinuria, edema, and acute kidney injury. Postinfectious Glomerulonephritis)
    • Lupus nephritis Lupus nephritis Glomerulonephritis associated with autoimmune disease systemic lupus erythematosus. Lupus nephritis is histologically classified into 6 classes: class I – normal glomeruli, class II – pure mesangial alterations, class III – focal segmental glomerulonephritis, class IV – diffuse glomerulonephritis, class V – diffuse membranous glomerulonephritis, and class VI – advanced sclerosing glomerulonephritis (the world health organization classification 1982). Diffuse Proliferative Glomerulonephritis (also chronic)
    • Membranoproliferative GN ( MPGN MPGN Membranoproliferative glomerulonephritis (MPGN) is also known as mesangiocapillary glomerulonephritis. Membranoproliferative glomerulonephritis is a pattern of glomerular injury characterized by mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (double contour formation). Membranoproliferative Glomerulonephritis; immune complex– and complement-mediated)
    • Rapidly progressive GN ( RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis) can be seen with:
      • Anti–glomerular basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) (GBM) disease ( Goodpasture syndrome Goodpasture Syndrome Goodpasture syndrome, also known as anti-glomerular basement membrane (GBM) disease, is an autoimmune disease characterized by circulating antibodies directed against glomerular and alveolar basement membranes. Affected individuals present with symptoms of rapidly progressive glomerulonephritis and alveolar hemorrhage. Goodpasture Syndrome)
      • Immune complex GN (due to lupus nephritis Lupus nephritis Glomerulonephritis associated with autoimmune disease systemic lupus erythematosus. Lupus nephritis is histologically classified into 6 classes: class I – normal glomeruli, class II – pure mesangial alterations, class III – focal segmental glomerulonephritis, class IV – diffuse glomerulonephritis, class V – diffuse membranous glomerulonephritis, and class VI – advanced sclerosing glomerulonephritis (the world health organization classification 1982). Diffuse Proliferative Glomerulonephritis, IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions, poststreptococcal, MPGN MPGN Membranoproliferative glomerulonephritis (MPGN) is also known as mesangiocapillary glomerulonephritis. Membranoproliferative glomerulonephritis is a pattern of glomerular injury characterized by mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (double contour formation). Membranoproliferative Glomerulonephritis, and pauci-immune GN seen with ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis-associated vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus)
  • Chronic GN (presents in 3 ways):

Classification

  • Primary GN:
    • IgA nephropathy IgA nephropathy IgA nephropathy (Berger’s disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy
    • MPGN MPGN Membranoproliferative glomerulonephritis (MPGN) is also known as mesangiocapillary glomerulonephritis. Membranoproliferative glomerulonephritis is a pattern of glomerular injury characterized by mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (double contour formation). Membranoproliferative Glomerulonephritis
    • Anti-GBM disease ( Goodpasture syndrome Goodpasture Syndrome Goodpasture syndrome, also known as anti-glomerular basement membrane (GBM) disease, is an autoimmune disease characterized by circulating antibodies directed against glomerular and alveolar basement membranes. Affected individuals present with symptoms of rapidly progressive glomerulonephritis and alveolar hemorrhage. Goodpasture Syndrome)
  • Hereditary disorders:
    • Alport syndrome Alport Syndrome Alport syndrome, also called hereditary nephritis, is a genetic disorder caused by a mutation in the genes encoding for the alpha chains of type IV collagen, resulting in the production of abnormal type IV collagen strands. Patients present with glomerulonephritis, hypertension, edema, hematuria, and proteinuria, as well as with ocular and auditory findings. Alport Syndrome
    • Thin basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) disease
  • Secondary GN:
    • Infectious Infectious Febrile Infant and postinfectious causes:
      • Group A beta-hemolytic Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus 
      • Mycoplasma Mycoplasma Mycoplasma is a species of pleomorphic bacteria that lack a cell wall, which makes them difficult to target with conventional antibiotics and causes them to not gram stain well. Mycoplasma bacteria commonly target the respiratory and urogenital epithelium. Mycoplasma pneumoniae (M. pneumoniae), the causative agent of atypical or “walking” pneumonia. Mycoplasma 
      • Salmonella typhi Salmonella typhi A serotype of Salmonella enterica which is the etiologic agent of typhoid fever. Enteric Fever (Typhoid Fever)
      • Staphylococcal infections Staphylococcal Infections Infections with bacteria of the genus staphylococcus. Glycopeptides (including bacterial endocarditis Bacterial endocarditis Inflammation of the endocardium caused by bacteria that entered the bloodstream. The strains of bacteria vary with predisposing factors, such as congenital heart defects; heart valve diseases; heart valve prosthesis implantation; or intravenous drug use. Endocarditis)
      • Visceral abscesses due to gram-negative bacteria gram-negative bacteria Bacteria which lose crystal violet stain but are stained pink when treated by gram’s method. Bacteriology
      • Malaria Malaria Malaria is an infectious parasitic disease affecting humans and other animals. Most commonly transmitted via the bite of a female Anopheles mosquito infected with microorganisms of the Plasmodium genus. Patients present with fever, chills, myalgia, headache, and diaphoresis. Plasmodium/Malaria
      • Schistosomiasis Schistosomiasis Infection with flukes (trematodes) of the genus schistosoma. Three species produce the most frequent clinical diseases: Schistosoma haematobium (endemic in Africa and the Middle East), Schistosoma Mansoni (in Egypt, northern and southern Africa, some West Indies islands, northern 2/3 of South america), and Schistosoma japonicum (in Japan, China, the Philippines, Celebes, Thailand, Laos). S. mansoni is often seen in Puerto Ricans living in the United States. Schistosoma/Schistosomiasis
      • Coxsackievirus Coxsackievirus Coxsackievirus is a member of a family of viruses called Picornaviridae and the genus Enterovirus. Coxsackieviruses are single-stranded, positive-sense RNA viruses, and are divided into coxsackie group A and B viruses. Both groups of viruses cause upper respiratory infections, rashes, aseptic meningitis, or encephalitis. Coxsackievirus
      • Cytomegalovirus Cytomegalovirus CMV is a ubiquitous double-stranded DNA virus belonging to the Herpesviridae family. CMV infections can be transmitted in bodily fluids, such as blood, saliva, urine, semen, and breast milk. The initial infection is usually asymptomatic in the immunocompetent host, or it can present with symptoms of mononucleosis. Cytomegalovirus
      • EBV EBV Epstein-barr virus (EBV) is a linear, double-stranded DNA virus belonging to the herpesviridae family. This highly prevalent virus is mostly transmitted through contact with oropharyngeal secretions from an infected individual. The virus can infect epithelial cells and B lymphocytes, where it can undergo lytic replication or latency. Epstein-Barr Virus
      • Hepatitis B Hepatitis B Hepatitis B virus (HBV) is a partially double-stranded DNA virus, which belongs to the Orthohepadnavirus genus and the Hepadnaviridae family. Most individuals with acute HBV infection are asymptomatic or have mild, self-limiting symptoms. Chronic infection can be asymptomatic or create hepatic inflammation, leading to liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis B Virus and C 
      • Measles Measles Measles (also known as rubeola) is caused by a single-stranded, linear, negative-sense RNA virus of the family Paramyxoviridae. It is highly contagious and spreads by respiratory droplets or direct-contact transmission from an infected person. Typically a disease of childhood, measles classically starts with cough, coryza, and conjunctivitis, followed by a maculopapular rash. Measles Virus
      • Mumps Mumps Mumps is caused by a single-stranded, linear, negative-sense RNA virus of the family Paramyxoviridae. Mumps is typically a disease of childhood, which manifests initially with fever, muscle pain, headache, poor appetite, and a general feeling of malaise, and is classically followed by parotitis. Mumps Virus/Mumps
      • Varicella
    • Connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology disorders: systemic lupus erythematosus Systemic lupus erythematosus Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus
    • Vasculitides Vasculitides Vasculitides are a group of conditions characterized by vasculitis, ischemia, and damage to the organs supplied by the affected vessels. The affected arteries are of different sizes and locations and vary by the type of vasculitis. Vasculitides
      • Eosinophilic granulomatosis with polyangiitis Granulomatosis with Polyangiitis A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis (EGPA; formerly, Churg-Strauss syndrome Churg-Strauss syndrome Widespread necrotizing angiitis with granulomas. Pulmonary involvement is frequent. Asthma or other respiratory infection may precede evidence of vasculitis. Eosinophilia and lung involvement differentiate this disease from polyarteritis nodosa. Vasculitides)
      • Microscopic polyangiitis Microscopic polyangiitis A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides ( MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides)
      • Granulomatosis with polyangiitis Granulomatosis with Polyangiitis A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis
      • IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions-associated vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus, also known as Henoch-Schönlein purpura Henoch-Schönlein Purpura Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura (not the same as IgA nephropathy IgA nephropathy IgA nephropathy (Berger’s disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy)
      • Polyarteritis nodosa Polyarteritis nodosa A form of necrotizing non-granulomatous inflammation occurring primarily in medium-sized arteries, often with microaneurysms. It is characterized by muscle, joint, and abdominal pain resulting from arterial infarction and scarring in affected organs. Polyarteritis nodosa with lung involvement is called churg-strauss syndrome. Vasculitides
    • Hematologic dyscrasias:
      • Mixed IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions cryoglobulinemia Cryoglobulinemia A condition characterized by the presence of abnormal quantities of cryoglobulins in the blood. Upon cold exposure, these abnormal proteins precipitate into the microvasculature leading to restricted blood flow in the exposed areas. Rapidly Progressive Glomerulonephritis
      • Thrombotic thrombocytopenic purpura Thrombotic thrombocytopenic purpura Thrombotic thrombocytopenic purpura (TTP) is a life-threatening condition due to either a congenital or an acquired deficiency of ADAMTS-13, a metalloproteinase that cleaves multimers of von Willebrand factor (VWF). The large multimers then aggregate excessive platelets resulting in microvascular thrombosis and an increase in consumption of platelets. Thrombotic Thrombocytopenic Purpura hemolytic uremic syndrome Hemolytic uremic syndrome A syndrome that is associated with microvascular diseases of the kidney, such as renal cortical necrosis. It is characterized by hemolytic anemia; thrombocytopenia; and acute renal failure. Hypocoagulable Conditions ( TTP TTP Thrombotic thrombocytopenic purpura (TTP) is a life-threatening condition due to either a congenital or an acquired deficiency of adamts-13, a metalloproteinase that cleaves multimers of von Willebrand factor (vWF). The large multimers then aggregate excessive platelets resulting in microvascular thrombosis and an increase in consumption of platelets. Thrombotic Thrombocytopenic Purpura HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome)
Urine microscopy - normal and dysmorphic rbcs

Urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat microscopy:
Normal RBC with circular appearance (left)
The 3 images to the right show dysmorphic RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology. Note the blebs Blebs Ischemic Cell Damage on the membrane and the “Mickey Mouse” cells.

Image: “Isomorphic red blood cells Red blood cells Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology ( RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology) and dysmorphic RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology, 400×” by Chu-Su Y., et al AL Amyloidosis. License: CC BY 4.0, cropped by Lecturio.

Pathophysiology

The 2 main mechanisms of glomerular injury in the nephritic syndromes are immune complex–mediated and complement dysregulation. Hereditary forms of GN (e.g., Alport syndrome Alport Syndrome Alport syndrome, also called hereditary nephritis, is a genetic disorder caused by a mutation in the genes encoding for the alpha chains of type IV collagen, resulting in the production of abnormal type IV collagen strands. Patients present with glomerulonephritis, hypertension, edema, hematuria, and proteinuria, as well as with ocular and auditory findings. Alport Syndrome) have different pathophysiologies.

Nephron Nephron The functional units of the kidney, consisting of the glomerulus and the attached tubule. Kidneys: Anatomy anatomy and physiology

  • Glomerular barrier Glomerular barrier A specialized barrier in the kidney, consisting of the fenestrated capillary endothelium; glomerular basement membrane; and glomerular epithelium (podocytes). The barrier prevents the filtration of plasma proteins. Glomerular Filtration: filtration structure of the nephron Nephron The functional units of the kidney, consisting of the glomerulus and the attached tubule. Kidneys: Anatomy that surrounds the glomerular capillaries Glomerular capillaries Kidneys: Anatomy and includes the following 3 layers:
    • Capillary endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology: walls of the capillary vessels
    • GBM: formed by the capillary endothelial and podocyte basal laminas
    • Epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology (podocytes): attached to the GBM with multiple foot processes Foot processes Nephrotic Syndrome
  • Nephritic syndrome primarily involves the capillary endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology and GBM.
  • Nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome primarily involves the epithelial layer with podocytes.
Glomerular barrier

Diagram of the glomerular barrier Glomerular barrier A specialized barrier in the kidney, consisting of the fenestrated capillary endothelium; glomerular basement membrane; and glomerular epithelium (podocytes). The barrier prevents the filtration of plasma proteins. Glomerular Filtration:
A: Fenestrated endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology of the glomerular capillaries Glomerular capillaries Kidneys: Anatomy
B: Basal membrane
C: Epithelial layer demonstrating podocyte foot processes Foot processes Nephrotic Syndrome and structural proteins Structural proteins Proteins and Peptides creating the slit diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy

Image by Lecturio.

Pathophysiology

  • Immune complex–mediated:
    • Antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination:
      • Can be foreign (e.g., bacterial) or self (e.g., autoimmune disease)
      • Can be circulating in the bloodstream or fixed in tissues 
    • Antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination + antibody = immune complex → inflammatory response → neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation and other inflammatory factors are recruited → tissue damage
      • Can form in the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment (e.g., PSGN PSGN Post-streptococcal glomerulonephritis (PSGN) is a type of nephritis that is caused by a prior infection with group A beta-hemolytic Streptococcus (GAS). The clinical presentation of PSGN can range from asymptomatic, microscopic hematuria to full-blown acute nephritic syndrome, which is characterized by red-to-brown urine, proteinuria, edema, and acute kidney injury. Postinfectious Glomerulonephritis)
      • Can also form directly in tissues (e.g., anti-GBM disease)
  • Complement dysregulation:
    • Normal complement system Complement system Serum glycoproteins participating in the host defense mechanism of complement activation that creates the complement membrane attack complex. Included are glycoproteins in the various pathways of complement activation (classical complement pathway; alternative complement pathway; and lectin complement pathway). Innate Immunity: Barriers, Complement, and Cytokines/process:
      • Complement is a component of the humoral immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs.
      • Cascade ends with the formation of a membrane attack complex Membrane attack complex A product of complement activation cascade, regardless of the pathways, that forms transmembrane channels causing disruption of the target cell membrane and cell lysis. It is formed by the sequential assembly of terminal complement components (complement C5b; complement C6; complement C7; complement C8; and complement C9) into the target membrane. The resultant C5b-8-poly-c9 is the ‘membrane attack complex’ or MAC. Type II Hypersensitivity Reaction (MAC) → compromises the integrity of the foreign cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane → cell lysis
    • Dysregulation in GN:
      • Compromises the integrity of the glomerular filtration Glomerular filtration The kidneys are primarily in charge of the maintenance of water and solute homeostasis through the processes of filtration, reabsorption, secretion, and excretion. Glomerular filtration is the process of converting the systemic blood supply into a filtrate, which will ultimately become the urine. Glomerular Filtration unit → RBC and protein leak into the urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat glomerular filtration Glomerular filtration The kidneys are primarily in charge of the maintenance of water and solute homeostasis through the processes of filtration, reabsorption, secretion, and excretion. Glomerular filtration is the process of converting the systemic blood supply into a filtrate, which will ultimately become the urine. Glomerular Filtration rate decreases
      • The alternative pathway Alternative pathway Complement activation initiated by the interaction of microbial antigens with complement C3b. When complement factor B binds to the membrane-bound C3b, complement factor d cleaves it to form alternative C3 convertase (c3bbb) which, stabilized by complement factor p, is able to cleave multiple complement C3 to form alternative C5 convertase (c3bbb3b) leading to cleavage of complement C5 and the assembly of complement membrane attack complex. Innate Immunity: Barriers, Complement, and Cytokines is overactive → inappropriate inflammatory response and neutrophil recruitment Recruitment Skeletal Muscle Contraction → tissue damage 
Primary pathways of the complement system

Primary pathways of the complement system Complement system Serum glycoproteins participating in the host defense mechanism of complement activation that creates the complement membrane attack complex. Included are glycoproteins in the various pathways of complement activation (classical complement pathway; alternative complement pathway; and lectin complement pathway). Innate Immunity: Barriers, Complement, and Cytokines
MBL: monoclonal B-cell lymphocytosis Lymphocytosis WBCs develop from stem cells in the bone marrow and are called leukocytes when circulating in the bloodstream. Lymphocytes are 1 of the 5 subclasses of WBCs. Lymphocytosis is an increase in the number or proportion of the lymphocyte subclass of WBCs, often as a result of an immune response to infection (known as reactive lymphocytosis). Lymphocytosis

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Types of Nephritic Syndrome

The primary and secondary causes of GN vary by etiology but have hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma and variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables degrees of proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children in common. Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma findings differ and are important to know.

IgA nephropathy IgA nephropathy IgA nephropathy (Berger’s disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy

  • Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
    • Most commonly presents as chronic GN:
    • Presents much less commonly as acute GN or RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis (approximately 5%–10%)
  • Diagnosis:
    • Labs: normal serum complement levels
    • Kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma findings:
      • Light microscopy: mesangial hypercellularity
      • Immunofluorescence: positive for IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions in the mesangium Mesangium The thin membranous structure supporting the adjoining glomerular capillaries. It is composed of glomerular mesangial cells and their extracellular matrix. IgA Nephropathy
      • Electron microscopy: mesangial immune deposits
  • Management:
    • Observation if creatinine is normal and proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children is < 500 mg/day
    • ACEi ACEi A class of drugs whose main indications are the treatment of hypertension and heart failure. They exert their hemodynamic effect mainly by inhibiting the renin-angiotensin system. They also modulate sympathetic nervous system activity and increase prostaglandin synthesis. They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility. Renin-Angiotensin-Aldosterone System Inhibitors if proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children is 500 mg–1000 mg/day
    • Steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors for progressive disease
    • Transplantation if progression to end-stage renal disease (ESRD)

Poststreptococcal glomerulonephritis Poststreptococcal Glomerulonephritis Post-streptococcal glomerulonephritis (PSGN) is a type of nephritis that is caused by a prior infection with group A beta-hemolytic Streptococcus (GAS). The clinical presentation of PSGN can range from asymptomatic, microscopic hematuria to full-blown acute nephritic syndrome, which is characterized by red-to-brown urine, proteinuria, edema, and acute kidney injury. Postinfectious Glomerulonephritis

  • Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
    • Most common cause of acute nephritic syndrome (but not concurrently) in children
    • Can present 1–3 weeks after a throat Throat The pharynx is a component of the digestive system that lies posterior to the nasal cavity, oral cavity, and larynx. The pharynx can be divided into the oropharynx, nasopharynx, and laryngopharynx. Pharyngeal muscles play an integral role in vital processes such as breathing, swallowing, and speaking. Pharynx: Anatomy infection caused by specific nephritogenic strains of group A beta-hemolytic Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus 
    • Can present 3–6 weeks after a skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions infection ( impetigo Impetigo Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic “honey-colored” crusts. Impetigo): caused by group A Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus or Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess
  • Diagnosis:
    • Labs: 
      • Streptozyme test: measures 5 different antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions including antistreptolysin Antistreptolysin Antibodies specific to streptolysins which indicate streptococcal infections. Postinfectious Glomerulonephritis-O after pharyngeal infection
      • Urinalysis Urinalysis Examination of urine by chemical, physical, or microscopic means. Routine urinalysis usually includes performing chemical screening tests, determining specific gravity, observing any unusual color or odor, screening for bacteriuria, and examining the sediment microscopically. Urinary Tract Infections (UTIs) in Children: hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma with RBC casts, +/– proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children
    • Kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma findings:
  • Management:
    • Supportive care
    • Antibiotics: only if the strep infection is still present at the time of diagnosis
    • Treat hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension and/or edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema:
      • Loop diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication (e.g., furosemide Furosemide A benzoic-sulfonamide-furan. It is a diuretic with fast onset and short duration that is used for edema and chronic renal insufficiency. Loop Diuretics)
      • Sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia and water restriction

Lupus Nephritis Lupus nephritis Glomerulonephritis associated with autoimmune disease systemic lupus erythematosus. Lupus nephritis is histologically classified into 6 classes: class I – normal glomeruli, class II – pure mesangial alterations, class III – focal segmental glomerulonephritis, class IV – diffuse glomerulonephritis, class V – diffuse membranous glomerulonephritis, and class VI – advanced sclerosing glomerulonephritis (the world health organization classification 1982). Diffuse Proliferative Glomerulonephritis

  • Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
    • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables; can present as acute/chronic GN or as RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis
    • Commonly will have a relapsing and remitting pattern once established
    • Can overlap with nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome
  • Diagnosis:
    • Lab findings:
      • Classical complement pathway pattern (low C3 and C4)
      • Specific diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests: ANA, double-stranded DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure (dsDNA)
    • Kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma findings (differ by class):
      • Class III (focal proliferative GN): < 50% glomeruli involvement with cellular proliferation; “wire loops”
      • Class IV (diffuse proliferative GN): > 50% glomeruli involvement with cellular proliferation; “wire loops”
      • Class V (membranous nephropathy): Thickened basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN)
  • Management:
    • Class I and II: conservative treatment with ACEi ACEi A class of drugs whose main indications are the treatment of hypertension and heart failure. They exert their hemodynamic effect mainly by inhibiting the renin-angiotensin system. They also modulate sympathetic nervous system activity and increase prostaglandin synthesis. They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility. Renin-Angiotensin-Aldosterone System Inhibitors for hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
    • Class III and IV: add immunosuppressant drugs ( steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors and cyclophosphamide Cyclophosphamide Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the liver to form the active aldophosphamide. It has been used in the treatment of lymphoma and leukemia. Its side effect, alopecia, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer. Immunosuppressants).
    • Class V: steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors + mycophenolate Mycophenolate Immunosuppressants mofetil + ACEi ACEi A class of drugs whose main indications are the treatment of hypertension and heart failure. They exert their hemodynamic effect mainly by inhibiting the renin-angiotensin system. They also modulate sympathetic nervous system activity and increase prostaglandin synthesis. They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility. Renin-Angiotensin-Aldosterone System Inhibitors for proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children
Renal histopathologic findings in a patient with systemic lupus erythematosus

Renal histopathologic findings in systemic lupus erythematosus Systemic lupus erythematosus Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus:
Light micrographs of a glomerulus show diffuse thickening of the glomerular basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) (periodic acid–silver methenamine stain; ×400) (a) with mesangial hypercellularity and mesangial matrix expansion (periodic acid–Schiff stain; ×400) (b). Electron microscopic analyses show numerous subepithelial Subepithelial Membranoproliferative Glomerulonephritis and mesangial electron-dense deposits, as well as deposits within the glomerular basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) with extensive fusion of foot processes Foot processes Nephrotic Syndrome (×5000) (c).

Image: “Renal histopathological findings” by Su X., et al AL Amyloidosis. License: CC BY 4.0

Anti–glomerular basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) disease ( Goodpasture syndrome Goodpasture Syndrome Goodpasture syndrome, also known as anti-glomerular basement membrane (GBM) disease, is an autoimmune disease characterized by circulating antibodies directed against glomerular and alveolar basement membranes. Affected individuals present with symptoms of rapidly progressive glomerulonephritis and alveolar hemorrhage. Goodpasture Syndrome)

  • Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
    • Only presents as RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis (medical emergency)
    • Goodpasture syndrome Goodpasture Syndrome Goodpasture syndrome, also known as anti-glomerular basement membrane (GBM) disease, is an autoimmune disease characterized by circulating antibodies directed against glomerular and alveolar basement membranes. Affected individuals present with symptoms of rapidly progressive glomerulonephritis and alveolar hemorrhage. Goodpasture Syndrome (also called crescentic):
      • Refers to renal and pulmonary involvement Pulmonary involvement Coccidioides/Coccidioidomycosis (pulmonary–renal syndrome)
      • Presents with hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis in 25%–60%
      • More likely in individuals < 30 years old
      • Older individuals > 50 years are more likely to have isolated GN.
  • Diagnosis:
    • Normal serum complement levels
    • Specific diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests:
      • Serum anti-GBM antibody
      • Serum ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis (up to half will be positive = overlap syndrome with ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus)
      • Chest x-ray Chest X-ray X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs. Pulmonary Function Tests/CT: Assess for pulmonary hemorrhage.
      • Bronchoalveolar lavage Bronchoalveolar lavage Washing out of the lungs with saline or mucolytic agents for diagnostic or therapeutic purposes. It is very useful in the diagnosis of diffuse pulmonary infiltrates in immunosuppressed patients. Pulmonary Fibrosis for definitive diagnosis
    • Kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma findings:
      • Light microscopy: crescents, necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage
      • Immunofluorescence: linear IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis deposition 
      • Electron microscopy: nonspecific findings
  • Management: 
    • Plasmapheresis Plasmapheresis Procedure whereby plasma is separated and extracted from anticoagulated whole blood and the red cells retransfused to the donor. Plasmapheresis is also employed for therapeutic use. Stevens-Johnson Syndrome
    • Immunosuppressants Immunosuppressants Immunosuppressants are a class of drugs widely used in the management of autoimmune conditions and organ transplant rejection. The general effect is dampening of the immune response. Immunosuppressants
    • Transplantation in individuals who develop ESRD

Immune complex–mediated membranoproliferative glomerulonephritis Membranoproliferative Glomerulonephritis Membranoproliferative glomerulonephritis (MPGN) is also known as mesangiocapillary glomerulonephritis. Membranoproliferative glomerulonephritis is a pattern of glomerular injury characterized by mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (double contour formation). Membranoproliferative Glomerulonephritis

  • Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
    • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables; can be triggered by a multitude of underlying diseases
    • Can present as acute/chronic GN or as RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis
    • Membranoproliferative glomerulonephritis Membranoproliferative Glomerulonephritis Membranoproliferative glomerulonephritis (MPGN) is also known as mesangiocapillary glomerulonephritis. Membranoproliferative glomerulonephritis is a pattern of glomerular injury characterized by mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (double contour formation). Membranoproliferative Glomerulonephritis often overlaps with nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome.
    • Commonly associated with mixed cryoglobulinemia Cryoglobulinemia A condition characterized by the presence of abnormal quantities of cryoglobulins in the blood. Upon cold exposure, these abnormal proteins precipitate into the microvasculature leading to restricted blood flow in the exposed areas. Rapidly Progressive Glomerulonephritis with hepatitis C Hepatitis C Hepatitis C is an infection of the liver caused by the hepatitis C virus (HCV). The infection can be transmitted through infectious blood or body fluids and may be transmitted during childbirth or through IV drug use or sexual intercourse. Hepatitis C virus can cause both acute and chronic hepatitis, ranging from a mild to a serious, lifelong illness including liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis C Virus
  • Diagnosis:
    • Labs:
      • Classical complement pathway pattern (low C3, low C4)
      • Hepatitis B Hepatitis B Hepatitis B virus (HBV) is a partially double-stranded DNA virus, which belongs to the Orthohepadnavirus genus and the Hepadnaviridae family. Most individuals with acute HBV infection are asymptomatic or have mild, self-limiting symptoms. Chronic infection can be asymptomatic or create hepatic inflammation, leading to liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis B Virus and C antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions
    • Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma findings:
  • Management:
    • Acute GN: steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors + mycophenolate Mycophenolate Immunosuppressants mofetil (avoid with very poor renal function)
    • RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis: IV steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors plus cyclophosphamide Cyclophosphamide Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the liver to form the active aldophosphamide. It has been used in the treatment of lymphoma and leukemia. Its side effect, alopecia, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer. Immunosuppressants

Complement-mediated membranoproliferative glomerulonephritis Membranoproliferative Glomerulonephritis Membranoproliferative glomerulonephritis (MPGN) is also known as mesangiocapillary glomerulonephritis. Membranoproliferative glomerulonephritis is a pattern of glomerular injury characterized by mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (double contour formation). Membranoproliferative Glomerulonephritis

  • Presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor:
    • Subtypes called dense deposit disease (DDD) and C3 glomerulonephritis are both rare.
    • Can present as acute/ chronic glomerulonephritis Chronic Glomerulonephritis Nephritic Syndrome in Children or as RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis
    • Drusen (fatty deposits in the retina Retina The ten-layered nervous tissue membrane of the eye. It is continuous with the optic nerve and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the choroid and the inner surface with the vitreous body. The outermost layer is pigmented, whereas the inner nine layers are transparent. Eye: Anatomy) may be seen with DDD.
  • Diagnosis:
    • Labs:
      • Alternative complement pathway pattern (low C3, normal C4)
      • Serum C3 nephritic factor
      • Factor I/factor H mutations
    • Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma findings:
      • Light microscopy: double-contour tram-track of GBM
      • Immunofluorescence: C3 positive
      • Electron microscopy: intramembranous dense deposits (only with degenerative disk disease Disk Disease Examination of the Lower Limbs)
  • Management:
    • Conservative with ACEi ACEi A class of drugs whose main indications are the treatment of hypertension and heart failure. They exert their hemodynamic effect mainly by inhibiting the renin-angiotensin system. They also modulate sympathetic nervous system activity and increase prostaglandin synthesis. They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility. Renin-Angiotensin-Aldosterone System Inhibitors if < 1.5 g/day proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children and normal creatinine
    • Steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors + mycophenolate Mycophenolate Immunosuppressants mofetil if ≥ 1.5 g/day proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children or abnormal creatinine
    • Transplantation is an option, but recurrence is possible in the graft Graft A piece of living tissue that is surgically transplanted Organ Transplantation.

Differential Diagnosis

  • Alport syndrome Alport Syndrome Alport syndrome, also called hereditary nephritis, is a genetic disorder caused by a mutation in the genes encoding for the alpha chains of type IV collagen, resulting in the production of abnormal type IV collagen strands. Patients present with glomerulonephritis, hypertension, edema, hematuria, and proteinuria, as well as with ocular and auditory findings. Alport Syndrome: also known as hereditary nephritis. Alport syndrome Alport Syndrome Alport syndrome, also called hereditary nephritis, is a genetic disorder caused by a mutation in the genes encoding for the alpha chains of type IV collagen, resulting in the production of abnormal type IV collagen strands. Patients present with glomerulonephritis, hypertension, edema, hematuria, and proteinuria, as well as with ocular and auditory findings. Alport Syndrome is a genetic disease of type IV collagen Type IV collagen A non-fibrillar collagen found in the structure of basement membrane. Collagen type IV molecules assemble to form a sheet-like network which is involved in maintaining the structural integrity of basement membranes. The predominant form of the protein is comprised of two alpha1(IV) subunits and one alpha2(IV) subunit, however, at least six different alpha subunits can be incorporated into the heterotrimer. Alport Syndrome of the basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN). Clinical presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor includes isolated microscopic hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma initially, which may be confused for IgA nephropathy IgA nephropathy IgA nephropathy (Berger’s disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy or thin basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) disease. There is also characteristic sensorineural hearing loss Sensorineural hearing loss Hearing loss resulting from damage to the cochlea and the sensorineural elements which lie internally beyond the oval and round windows. These elements include the auditory nerve and its connections in the brainstem. Hearing Loss, as well as ocular abnormalities. CKD CKD Chronic kidney disease (CKD) is kidney impairment that lasts for ≥ 3 months, implying that it is irreversible. Hypertension and diabetes are the most common causes; however, there are a multitude of other etiologies. In the early to moderate stages, CKD is usually asymptomatic and is primarily diagnosed by laboratory abnormalities. Chronic Kidney Disease develops over time and can progress to ESRD requiring transplantation.
  • Thin basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) disease: also known as benign Benign Fibroadenoma familial hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma. This genetic disease presents with isolated microscopic hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma and may be confused with IgA nephropathy IgA nephropathy IgA nephropathy (Berger’s disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy or Alport syndrome Alport Syndrome Alport syndrome, also called hereditary nephritis, is a genetic disorder caused by a mutation in the genes encoding for the alpha chains of type IV collagen, resulting in the production of abnormal type IV collagen strands. Patients present with glomerulonephritis, hypertension, edema, hematuria, and proteinuria, as well as with ocular and auditory findings. Alport Syndrome. Kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma only shows diffuse thinning of the GBM on electron microscopy. The overall prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas for thin basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) disease is good. Individuals should receive an ACEi ACEi A class of drugs whose main indications are the treatment of hypertension and heart failure. They exert their hemodynamic effect mainly by inhibiting the renin-angiotensin system. They also modulate sympathetic nervous system activity and increase prostaglandin synthesis. They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility. Renin-Angiotensin-Aldosterone System Inhibitors and undergo long-term follow-up, as there may be overlap with Alport syndrome Alport Syndrome Alport syndrome, also called hereditary nephritis, is a genetic disorder caused by a mutation in the genes encoding for the alpha chains of type IV collagen, resulting in the production of abnormal type IV collagen strands. Patients present with glomerulonephritis, hypertension, edema, hematuria, and proteinuria, as well as with ocular and auditory findings. Alport Syndrome and some will develop CKD CKD Chronic kidney disease (CKD) is kidney impairment that lasts for ≥ 3 months, implying that it is irreversible. Hypertension and diabetes are the most common causes; however, there are a multitude of other etiologies. In the early to moderate stages, CKD is usually asymptomatic and is primarily diagnosed by laboratory abnormalities. Chronic Kidney Disease.
  • Henoch-Schönlein purpura Henoch-Schönlein Purpura Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura: also known as IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus. Henoch-Schönlein purpura Henoch-Schönlein Purpura Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura is primarily a pediatric disease and is the most common cause of vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus in children. This condition involves the deposition of IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions immune complexes Immune complexes The complex formed by the binding of antigen and antibody molecules. The deposition of large antigen-antibody complexes leading to tissue damage causes immune complex diseases. C3 Deficiency in multiple vessels following a trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation (infection/environmental) and includes skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, GI, and musculoskeletal symptoms. The renal findings are very similar to those for IgA nephropathy IgA nephropathy IgA nephropathy (Berger’s disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy, but the disease is often self-limited in children, and kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma and steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors are often not needed.

References

  1. Appel, G. B., Kaplan, A. A. (2020). Overview of the classification and treatment of rapidly progressive (crescentic) glomerulonephritis. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/overview-of-the-classification-and-treatment-of-rapidly-progressive-crescentic-glomerulonephritis
  2. Bomback, A. S., Appel, G. B. (2021). Lupus nephritis: diagnosis and classification. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/lupus-nephritis-diagnosis-and-classification
  3. Fervenza, F. C., Sethi, S. (2021). Membranoproliferative glomerulonephritis: Classification, clinical features, and diagnosis. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/membranoproliferative-glomerulonephritis-classification-clinical-features-and-diagnosis
  4. Fervenza, F. C., Sethi, S. (2020). Membranoproliferative glomerulonephritis: treatment and prognosis. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/membranoproliferative-glomerulonephritis-treatment-and-prognosis
  5. Kashtan, C. E., Simon, J. F. (2020). Isolated and persistent glomerular hematuria in adults. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/isolated-and-persistent-glomerular-hematuria-in-adults
  6. Kopel, T., Salant, D. J. (2020). C3 glomerulopathies: Dense deposit disease and C3 glomerulonephritis. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/c3-glomerulopathies-dense-deposit-disease-and-c3-glomerulonephritis
  7. McAdoo, S. P., Pusey, C. D. (2017). Anti-glomerular basement membrane disease. Clinical Journal of the American Society of Nephrology 12:1162–1172. https://doi.org/10.2215/CJN.01380217
  8. Niaudet, P. (2020). Poststreptococcal glomerulonephritis. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/poststreptococcal-glomerulonephritis
  9. Radhakrishnan, J. (2021). Glomerular disease: Evaluation and differential diagnosis in adults. UpToDate. Retrieved October 25, 2021, from https://www.uptodate.com/contents/glomerular-disease-evaluation-and-differential-diagnosis-in-adults

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