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Renal Artery Stenosis

Renal artery Renal artery A branch of the abdominal aorta which supplies the kidneys, adrenal glands and ureters. Glomerular Filtration stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS) (RAS) is the narrowing of one or both renal arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology, usually caused by atherosclerotic disease or by fibromuscular dysplasia Dysplasia Cellular Adaptation. If the stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS) is severe enough, the stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS) causes decreased renal blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure, which activates the renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation-angiotensin- aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia system ( 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) and leads to renovascular 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 (RVH), which only accounts for a small fraction of all cases of 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. Renovascular 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 can be associated with abdominal bruits, renal insufficiency, or progressive renal atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation. Diagnosis is by 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 followed by imaging studies, including duplex ultrasonography Duplex ultrasonography Ultrasonography applying the doppler effect combined with real-time imaging. The real-time image is created by rapid movement of the ultrasound beam. A powerful advantage of this technique is the ability to estimate the velocity of flow from the doppler shift frequency. Hypercoagulable States, magnetic resonance angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery ( MRA MRA Imaging of the Heart and Great Vessels), computed tomography angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery ( CTA CTA A non-invasive method that uses a ct scanner for capturing images of blood vessels and tissues. A contrast material is injected, which helps produce detailed images that aid in diagnosing vascular diseases. Pulmonary Function Tests), and sometimes catheter-based angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery. Revascularization Revascularization Thromboangiitis Obliterans (Buerger’s Disease) is usually reserved for cases in which medical therapy has failed.

Last updated: 31 Mar, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Epidemiology and Etiology

Epidemiology

  • Renal artery Renal artery A branch of the abdominal aorta which supplies the kidneys, adrenal glands and ureters. Glomerular Filtration stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS) (RAS) accounts for < 2% of all cases of 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.
  • 2 main types of RAS:
    • Atherosclerotic type: 
      • 80% of all RAS cases
      • Strong association with atherosclerosis Atherosclerosis Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. Atherosclerosis in other parts of the body
      • Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship > 45 years of age, males > females
      • More common in Whites than in Blacks
      • Present in 10%–40% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with acute, severe, or refractory hypertension Refractory hypertension Blood pressure that cannot be controlled even with maximally tolerated doses of ≥ 5 drugs. Uncontrolled Hypertension 
      • Bilateral disease is present in 23%–54% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship (rarely do both sides show the same degree of stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS)).
    • Fibromuscular dysplasia Dysplasia Cellular Adaptation ( FMD FMD Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, medium-sized angiopathy due to fibroplasia of the vessel wall. The condition leads to complications related to arterial stenosis, aneurysm, or dissection. Fibromuscular Dysplasia) type:
      • 20% of all RAS cases
      • 90% of adult cases are in women.
      • Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are women < 50 years but all ages can be affected.
      • May be associated with FMD FMD Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, medium-sized angiopathy due to fibroplasia of the vessel wall. The condition leads to complications related to arterial stenosis, aneurysm, or dissection. Fibromuscular Dysplasia of the carotid and vertebral arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology

Etiology

  • Atherosclerosis Atherosclerosis Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. Atherosclerosis type: diffuse atherosclerosis Atherosclerosis Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. Atherosclerosis usually present, but can be isolated
  • FMD FMD Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, medium-sized angiopathy due to fibroplasia of the vessel wall. The condition leads to complications related to arterial stenosis, aneurysm, or dissection. Fibromuscular Dysplasia type: unknown etiology but genetics Genetics Genetics is the study of genes and their functions and behaviors. Basic Terms of Genetics believed to play an important role
  • Rare causes of RAS (approximately 1% of cases):
    • Extrinsic compression Compression Blunt Chest Trauma: usually by tumor Tumor Inflammation
    • Intimal dissection: caused by trauma or endovascular intervention
    • Thromboembolism Thromboembolism Obstruction of a blood vessel (embolism) by a blood clot (thrombus) in the blood stream. Systemic Lupus Erythematosus: caused by local sources (e.g., trauma, 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) or by distant emboli (e.g., from left atrium or fat emboli from fractures)
    • Iatrogenic Iatrogenic Any adverse condition in a patient occurring as the result of treatment by a physician, surgeon, or other health professional, especially infections acquired by a patient during the course of treatment. Anterior Cord Syndrome causes: migration and/or placement of endovascular aortic stent over the renal orifices 

Pathophysiology

  • Pathogenesis of all RAS cases:
    • Significant decrease of lumen ≥ 70% (less than 30% patent) with poststenotic gradient → blood pressure is affected
    • Renal hypoperfusion → activation of the renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation-angiotensin- aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia system ( 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) → increased renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation, angiotensin, and aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia → increased sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia (Na) retention and peripheral vascular resistance Vascular Resistance The force that opposes the flow of blood through a vascular bed. It is equal to the difference in blood pressure across the vascular bed divided by the cardiac output. Vascular Resistance, Flow, and Mean Arterial Pressure
    • Renovascular (secondary) 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 (RVH) is the final result → affects both kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy and other target organs
  • RAS caused by atherosclerosis Atherosclerosis Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. Atherosclerosis:
    • Usually involves the aortic orifice or the proximal main renal artery Renal artery A branch of the abdominal aorta which supplies the kidneys, adrenal glands and ureters. Glomerular Filtration
    • Without treatment, 50% of cases progress, sometimes to complete obstruction.
  • RAS caused by fibromuscular dysplasia Dysplasia Cellular Adaptation:
    • Medial fibroplasia Fibroplasia Fibromuscular Dysplasia represents the most common dysplastic lesion, but intima  fibroplasia Fibroplasia Fibromuscular Dysplasia and fibrous Fibrous Fibrocystic Change hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation of the adventitia also occur.
    • Typically, involves the mid- or distal main renal artery Renal artery A branch of the abdominal aorta which supplies the kidneys, adrenal glands and ureters. Glomerular Filtration or the intrarenal branches 
    • Focal loss of the internal elastic Elastic Connective Tissue: Histology lamina, with intervening fibromuscular hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation, produces the typical “string of beads” appearance on an angiogram.
    • Rarely leads to complete obstruction

Clinical Presentation and Diagnosis

Clinical signs and medical history

  • Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are asymptomatic, with only mild hemodynamic effects, if the lumen is < 70% occluded.
  • RVH should be suspected, and investigation for RVH initiated, if there are any of the following findings:
    • Diastolic 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 develops abruptly in a patient < 30 years or > 50 years.
    • New or previously stable 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 rapidly worsens.
    • Very severe 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: systolic ≥ 180 and/or diastolic ≥ 120 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg
    • 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 with worsening renal function or refractory to drug treatment
    • Elevated serum creatinine within 1 week of starting an angiotensin-converting enzyme inhibitor ( 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), angiotensin II Angiotensin II An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the c-terminal by angiotensin converting enzyme. The amino acid in position 5 varies in different species. To block vasoconstriction and hypertension effect of angiotensin II, patients are often treated with ace inhibitors or with angiotensin II type 1 receptor blockers. Renal Sodium and Water Regulation receptor Receptor Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors blocker (ARB), or a direct renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation inhibitor
    • Abdominal bruit Abdominal Bruit Abdominal Examination on 1 side
    • History of trauma to the back or flank or acute pain Acute pain Intensely discomforting, distressful, or agonizing sensation associated with trauma or disease, with well-defined location, character, and timing. Pain Management in the back or flank region with or without hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma (suggestive of arterial injury Arterial Injury Hemothorax
    • Asymmetric renal size (> 1 cm difference) discovered incidentally by imaging 
    • Recurrent episodes of unexplained acute pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema or heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) 
  • Atherosclerotic-type RAS:
    • > 50 years of age
    • Strong association with other cardiovascular pathologies
    • Often presents with concurrent small-vessel disease in kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy
    • Bilateral renal arterial stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS) is associated with more widespread atherosclerotic disease, higher serum creatinine levels, and higher mortality Mortality All deaths reported in a given population. Measures of Health Status than the unilateral disease.
  • FMD FMD Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, medium-sized angiopathy due to fibroplasia of the vessel wall. The condition leads to complications related to arterial stenosis, aneurysm, or dissection. Fibromuscular Dysplasia-type RAS:
    • Mostly in premenopausal women 15–50 years of age
    • Strongly suspect if 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 occurs in a child
    • Typically, found incidentally on imaging
    • A systolic-diastolic bruit in the epigastrium Epigastrium Surgical Anatomy of the Abdomen is present in only 50% of FMD FMD Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, medium-sized angiopathy due to fibroplasia of the vessel wall. The condition leads to complications related to arterial stenosis, aneurysm, or dissection. Fibromuscular Dysplasia cases.

Diagnostic procedures

Additional 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 can be used in the following cases:

However, the tests are expensive and may have serious side effects, especially if renal insufficiency is present.

  • Noninvasive tests: less reliable for FMD FMD Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, medium-sized angiopathy due to fibroplasia of the vessel wall. The condition leads to complications related to arterial stenosis, aneurysm, or dissection. Fibromuscular Dysplasia, related to distally located lesions:
    • Duplex Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography) ultrasonography
    • Computed tomographic angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery ( CTA CTA A non-invasive method that uses a ct scanner for capturing images of blood vessels and tissues. A contrast material is injected, which helps produce detailed images that aid in diagnosing vascular diseases. Pulmonary Function Tests)
    • Magnetic resonance angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery ( MRA MRA Imaging of the Heart and Great Vessels)
    • Captopril Captopril A potent and specific inhibitor of peptidyl-dipeptidase a. It blocks the conversion of angiotensin I to angiotensin II, a vasoconstrictor and important regulator of arterial blood pressure. Captopril acts to suppress the renin-angiotensin system and inhibits pressure responses to exogenous angiotensin. Hypertension Drugs renogram: radionuclide renography using captopril Captopril A potent and specific inhibitor of peptidyl-dipeptidase a. It blocks the conversion of angiotensin I to angiotensin II, a vasoconstrictor and important regulator of arterial blood pressure. Captopril acts to suppress the renin-angiotensin system and inhibits pressure responses to exogenous angiotensin. Hypertension Drugs, 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, mainly used to determine the relative function of each kidney
  • Invasive testing: intra-arterial angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery:
    • Gold standard for assessing RAS
    • Perform only after non-invasive testing has been done.
    • Carries risk of atheroembolism Atheroembolism An embolus is an intravascular solid, liquid, or gaseous material that is carried by the blood to a site distant from its point of origin. Emboli of all types warrant immediate medical attention. The majority of emboli dislodge from a thrombus, forming a thromboembolus. Other less common nonthrombotic types of emboli are cholesterol, fat, air, amniotic fluid, and tumor emboli. Nonthrombotic Embolism

Laboratory testing

  • Routine testing to evaluate kidney function by estimated glomerular filtration rate Glomerular filtration rate The volume of water filtered out of plasma through glomerular capillary walls into Bowman’s capsules per unit of time. It is considered to be equivalent to inulin clearance. Kidney Function Tests ( GFR GFR The volume of water filtered out of plasma through glomerular capillary walls into Bowman’s capsules per unit of time. It is considered to be equivalent to inulin clearance. Kidney Function Tests, from serum creatinine) and 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
  • Other labs:
    • Complete blood count (CBC)
    • Serum electrolyte levels ( sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia, potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia, chloride Chloride Inorganic compounds derived from hydrochloric acid that contain the Cl- ion. Electrolytes, and total carbon dioxide)
    • Blood urea nitrogen Blood urea nitrogen The urea concentration of the blood stated in terms of nitrogen content. Serum (plasma) urea nitrogen is approximately 12% higher than blood urea nitrogen concentration because of the greater protein content of red blood cells. Increases in blood or serum urea nitrogen are referred to as azotemia and may have prerenal, renal, or postrenal causes. Acute Kidney Injury (BUN)
    • Lipid panel and fasting glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance 
  • Findings:
    • In mild RAS, insufficient to affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment blood pressure → no abnormal labs
    • If RAS is severe enough to affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment blood pressure (decrease of lumen ≥ 70%, with poststenotic gradient), specific testing is of limited value (poor sensitivity Sensitivity Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Blotting Techniques or specificity Specificity Specificity is the probability of correctly determining the absence of a condition. Immunoassays):
      • Plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation activity ( PRA PRA Purine and Pyrimidine Metabolism) is elevated in only 50%–80% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with renovascular 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.
      • Renal vein Renal vein Short thick veins which return blood from the kidneys to the vena cava. Glomerular Filtration renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation measurements have many false positives and negatives.

Management

Medical therapy

  • Blockade of the renin Renin A highly specific (leu-leu) endopeptidase that generates angiotensin I from its precursor angiotensinogen, leading to a cascade of reactions which elevate blood pressure and increase sodium retention by the kidney in the renin-angiotensin system. Renal Sodium and Water Regulation-angiotensin system ( ACEIs ACEIs 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. Heart Failure and Angina Medication, ARBs ARBs Agents that antagonize angiotensin receptors. Many drugs in this class specifically target the angiotensin type 1 receptor. Heart Failure and Angina Medication)
  • Blood pressure control ( calcium channel blockers Calcium Channel Blockers Calcium channel blockers (CCBs) are a class of medications that inhibit voltage-dependent L-type calcium channels of cardiac and vascular smooth muscle cells. The inhibition of these channels produces vasodilation and myocardial depression. There are 2 major classes of CCBs: dihydropyridines and non-dihydropyridines. Class 4 Antiarrhythmic Drugs (Calcium Channel Blockers), diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication, beta blockers)
  • Lifestyle changes: cessation of tobacco
  • Statins Statins Statins are competitive inhibitors of HMG-CoA reductase in the liver. HMG-CoA reductase is the rate-limiting step in cholesterol synthesis. Inhibition results in lowered intrahepatocytic cholesterol formation, resulting in up-regulation of LDL receptors and, ultimately, lowering levels of serum LDL and triglycerides. Statins in atherosclerotic RAS
  • Antiplatelet therapy

Invasive procedures

  • Revascularization Revascularization Thromboangiitis Obliterans (Buerger’s Disease) is usually reserved for cases in which medical therapy has failed.
  • Major complications occur in 5%–9% of cases, even with experienced operators.
  • Procedures include percutaneous transluminal renal angioplasty Angioplasty Reconstruction or repair of a blood vessel, which includes the widening of a pathological narrowing of an artery or vein by the removal of atheromatous plaque material and/or the endothelial lining as well, or by dilatation (balloon angioplasty) to compress an atheroma. Except for endarterectomy, usually these procedures are performed via catheterization as minimally invasive endovascular procedures. Cardiac Surgery or aortorenal bypass surgery.
  • Therapeutic nephrectomy Nephrectomy Excision of kidney. Renal Cell Carcinoma is advised in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with uncontrolled hypertension Uncontrolled hypertension Although hypertension is defined as a blood pressure of > 130/80 mm Hg, individuals can present with comorbidities of severe asymptomatic or “uncontrolled” hypertension (≥ 180 mm Hg systolic and/or ≥ 120 mm Hg diastolic) that carries with it a significant risk of morbidity and mortality. Uncontrolled Hypertension and unilateral renovascular occlusion, especially if the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy are poorly functioning (< 15% of total GFR GFR The volume of water filtered out of plasma through glomerular capillary walls into Bowman’s capsules per unit of time. It is considered to be equivalent to inulin clearance. Kidney Function Tests).

Differential Diagnosis

Primary (“essential”) 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

The most common type of 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, with an unknown etiology. In 2017, the American College of Cardiology/ American Heart Association American Heart Association A voluntary organization concerned with the prevention and treatment of heart and vascular diseases. Congestive Heart Failure (ACC/AHA) revised their definitions, which may vary among different countries:

  • Normal blood pressure: systolic < 120 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg and diastolic < 80 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg
  • Elevated blood pressure: systolic 120–129 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg and diastolic < 80 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg
  • 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 stage 1 Stage 1 Trypanosoma brucei/African trypanosomiasis: systolic 130–139 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg or diastolic 80–89 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg
  • 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 stage 2: systolic at least 140 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg or diastolic at least 90 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma Hg

Secondary causes of 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

Five to ten percent of all cases of 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 include the following conditions:

  • Primary kidney disease: suspected with elevated serum creatinine concentration and/or abnormal urinalysis. Chronic kidney disease typically has a persistent and progressive reduction in GFR, but differential diagnosis from RVH can be difficult.
  • Primary aldosteronism: usually caused by an aldosterone-producing adenoma in the adrenal gland or bilateral adrenal hyperplasia. Clues include hypokalemia and increased plasma aldosterone to plasma renin activity.
  • Sleep apnea syndrome: characterized by repeated apneic episodes at night due to passive collapse of the pharyngeal muscles during inspiration. Usually occurs in obese men who snore loudly while asleep. Can have hypertension, headache, cardiac arrhythmias, daytime somnolence and fatigue, confusion, personality changes, and depression.
  • Oral contraceptives: normally, can elevate the blood pressure to hypertensive levels
  • Pheochromocytoma: a catecholamine-secreting tumor from chromaffin cells of the adrenal medulla or the sympathetic ganglia. Paroxysmal elevations in blood pressure occur, with the classic symptom triad of pounding headache, palpitations, and sweating. 
  • Cushing’s syndrome: caused by excess corticosteroid, which may be exogenous or endogenous, usually from a benign adrenal adenoma. Presents with Cushingoid facies, central obesity, proximal muscle weakness, and ecchymoses. 
  • Coarctation of the aorta: a major cause of secondary hypertension in young children but may be diagnosed initially in adulthood. Causes hypertension in the upper extremities, low blood pressure in the lower extremities, and diminished or delayed femoral pulses (“brachial-femoral delay”). May auscultate a “machinery murmur” from the aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy over the posterior thorax. 
  • Hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto’s disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism: symptoms of hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto’s disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism ( fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia, sensitivity Sensitivity Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Blotting Techniques to cold, weight gain, constipation Constipation Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Constipation, depression, muscle aches, and cramps Cramps Ion Channel Myopathy) with an elevated serum thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy-stimulating hormone (TSH) level.
  • Primary hyperparathyroidism Primary hyperparathyroidism A condition of abnormally elevated output of parathyroid hormone due to parathyroid hyperplasia or parathyroid neoplasms. It is characterized by the combination of hypercalcemia, phosphaturia, elevated renal 1, 25-dihydroxyvitamin d3 synthesis, and increased bone resorption. Hyperparathyroidism: due to parathyroid Parathyroid The parathyroid glands are 2 pairs of small endocrine glands found in close proximity to the thyroid gland. The superior parathyroid glands are lodged within the parenchyma of the upper poles of the right and left thyroid lobes; the inferior parathyroid glands are close to the inferior tips or poles of the lobes. Parathyroid Glands: Anatomy adenoma and associated with hypercalcemia Hypercalcemia Hypercalcemia (serum calcium > 10.5 mg/dL) can result from various conditions, the majority of which are due to hyperparathyroidism and malignancy. Other causes include disorders leading to vitamin D elevation, granulomatous diseases, and the use of certain pharmacological agents. Symptoms vary depending on calcium levels and the onset of hypercalcemia. Hypercalcemia, elevated levels of parathyroid Parathyroid The parathyroid glands are 2 pairs of small endocrine glands found in close proximity to the thyroid gland. The superior parathyroid glands are lodged within the parenchyma of the upper poles of the right and left thyroid lobes; the inferior parathyroid glands are close to the inferior tips or poles of the lobes. Parathyroid Glands: Anatomy hormone
  • Renal atheroemboli: also called cholesterol Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Cholesterol Metabolism crystal emboli, usually affects older patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with diffuse erosive atherosclerosis Atherosclerosis Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. Atherosclerosis. Renal atheroemboli occur when portions of an atherosclerotic plaque Plaque Primary Skin Lesions break off and embolize distally. Can affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy or other organs.
  • Chemotherapeutic agents: agent-related kidney injury by a thrombotic microangiopathy pathway or by inhibiting vascular endothelial growth factor Vascular endothelial growth factor A family of angiogenic proteins that are closely-related to vascular endothelial growth factor a. They play an important role in the growth and differentiation of vascular as well as lymphatic endothelial cells. Wound Healing (VEGF) signaling pathways

References

  1. Textor, S. (2018). In Jameson, J.L., et al. (Ed.), Harrison’s Principles of Internal Medicine (20th ed. Vol 2, pp. 1906-1909).
  2. Chang, A., Laszik, Z.G. (2020). The Kidney. In Kumar, V., Abbas, A. K., Aster, J.C., (Eds), Robbins & Cotran Pathologic Basis of Disease, 10 ed. (pp. 936–940). Elsevier, Inc.
  3. Textor, S. (2020). Treatment of unilateral atherosclerotic renal artery stenosis. UpToDate. Retrieved on September 29, 2020, from https://www.uptodate.com/contents/treatment-of-unilateral-atherosclerotic-renal-artery-stenosis
  4. Textor, S. (2020). Establishing the diagnosis of renovascular hypertension. UpToDate. Retrieved on September 29, 2020, from https://www.uptodate.com/contents/establishing-the-diagnosis-of-renovascular-hypertension?search=renal%20stenosis&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2
  5. Textor, S. (2020). Clinical manifestations and diagnosis of chronic kidney disease resulting from atherosclerotic renal artery stenosis. UpToDate. Retrieved on September 29, 2020, from https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-chronic-kidney-disease-resulting-from-atherosclerotic-renal-artery-stenosis?search=renal%20stenosis&source=search_result&selectedTitle=4~150&usage_type=default&display_rank=4
  6. Textor, S. (2020). Evaluation of secondary hypertension. UpToDate. Retrieved on September 29, 2020, from https://www.uptodate.com/contents/evaluation-of-secondary-hypertension?search=renal%20artery%20stenosis&source=search_result&selectedTitle=5~150&usage_type=default&display_rank=5
  7. Textor, S.(2020). Treatment of bilateral atherosclerotic renal artery stenosis or stenosis to a solitary functioning kidney. Retrieved on September 30, 2020, from: https://www.uptodate.com/contents/treatment-of-bilateral-atherosclerotic-renal-artery-stenosis-or-stenosis-to-a-solitary-functioning-kidney?search=Bilateral%20renal%20artery%20stenosis&source=search_result&selectedTitle=1~26&usage_type=default&display_rank=1#H11539312
  8. Bakris G.L. (2019). Renovascular Hypertension. MSD Manual Professional Version. https://www.msdmanuals.com/en-nz/professional/cardiovascular-disorders/hypertension/renovascular-hypertension
  9. Unger, T., Borghi, C., Charchar, F., et al. (2020). Global Hypertension Practice Guidelines. 2020 International Society of Hypertension. Hypertension, 2020(75). 1334–1357. https://doi.org/10.1161/HYPERTENSIONAHA.120.15026

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