Renal tubular acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis (RTA) is an imbalance in physiologic pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance caused by the kidney’s inability to acidify 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 to maintain blood pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance at physiologic levels. Renal tubular acidoses exist in multiple types, including distal RTA ( type 1 Type 1 Spinal Muscular Atrophy), proximal RTA ( type 2 Type 2 Spinal Muscular Atrophy), and hyperkalemic RTA ( type 4 Type 4 Spinal Muscular Atrophy). Depending on the type of RTA, various mechanisms cause dysfunction of renal acid–base handling, resulting in a non–anion-gap metabolic acidosis Metabolic acidosis The renal system is responsible for eliminating the daily load of non-volatile acids, which is approximately 70 millimoles per day. Metabolic acidosis occurs when there is an increase in the levels of new non-volatile acids (e.g., lactic acid), renal loss of HCO3-, or ingestion of toxic alcohols. Metabolic Acidosis. All RTAs present clinically with some degree of metabolic acidosis Metabolic acidosis The renal system is responsible for eliminating the daily load of non-volatile acids, which is approximately 70 millimoles per day. Metabolic acidosis occurs when there is an increase in the levels of new non-volatile acids (e.g., lactic acid), renal loss of HCO3-, or ingestion of toxic alcohols. Metabolic Acidosis; however, distal RTA and proximal RTA also have hypokalemia Hypokalemia Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. Hypokalemia, while hyperkalemic RTA does not. Diagnosis is primarily through the history and laboratory analysis, including measurement of serum and 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 anion gaps. Treatment involves the correction of chronic metabolic acidosis Metabolic acidosis The renal system is responsible for eliminating the daily load of non-volatile acids, which is approximately 70 millimoles per day. Metabolic acidosis occurs when there is an increase in the levels of new non-volatile acids (e.g., lactic acid), renal loss of HCO3-, or ingestion of toxic alcohols. Metabolic Acidosis with alkali to prevent its long-term catabolic effects on bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types and muscles, as well as addressing any underlying causes leading to the RTA.
Last updated: 21 Jan, 2022
Renal tubular acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis (RTA) is an imbalance in physiologic pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance caused by the kidney’s inability to acidify 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 to maintain blood pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance at physiologic levels.
RTA can be classified based on the clinical characteristics and physiologic defect:
Comparison of the types of RTA, including the clinical characteristics, physiologic defects, and potential etiologies:
Characteristics | Impaired H+
secretion
Secretion
Coagulation Studies by the distal segments
|
---|---|
Renal defect |
|
Etiology |
|
Characteristics | Impaired proximal HCO3 reabsorption
|
---|---|
Renal defect | Nonspecific tubule dysfunction or mutations in genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure involved in HCO3– reabsorption |
Etiology |
|
Characteristics | Impaired
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
release
Release
Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane.
Virology or response
|
---|---|
Renal defect | Impaired Na+ reabsorption via epithelial Na+ channel |
Etiology |
Congenital
Congenital
Chorioretinitis
hypoaldosteronism
Hypoaldosteronism
Hypoaldosteronism is a hormonal disorder characterized by low levels of aldosterone. These low levels can be caused by decreased aldosterone production or a peripheral resistance to aldosterone. When hypoaldosteronism occurs as a result of an acquired decrease in renin production, the condition is more commonly referred to as renal tubular acidosis (RTA) type 4.
Hypoaldosteronism (Addison disease)
|
In adults, the most common causes are:
In children, the most common cause is genetic:
Other causes:
Nephrocalcinosis
Nephrocalcinosis
A condition characterized by calcification of the renal tissue itself. It is usually seen in distal renal tubular acidosis with calcium deposition in the distal kidney tubules and the surrounding interstitium. Nephrocalcinosis causes renal insufficiency.
X-linked Hypophosphatemic Rickets:
Calcium deposits are visible in 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 in cases of hypercalciuria. This condition can arise from multiple causes, including hyperparathyroidism, vitamin D intoxication, and sarcoidosis and can result in type 1 renal tubular
acidosis
Acidosis
A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up.
Respiratory Acidosis.
In adults, the most common cause is monoclonal gammopathy Monoclonal gammopathy Conditions characterized by the presence of m protein (monoclonal protein) in serum or urine without clinical manifestations of plasma cell dyscrasia. MALT Lymphoma:
In children, the most common causes are:
Other causes:
In adults, the most common causes are:
Other causes:
The pathophysiology of distal RTA (type 1) is impaired acid secretion Secretion Coagulation Studies at the collecting duct Collecting duct Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of bellini) which opens on the summit of the papilla. Renal Cell Carcinoma of the distal tubule.
Normal process of urinary acidification:
Abnormal processes leading to distal RTA:
Complications:
Intercalated cells Intercalated cells Tubular System in distal RTA (type I)
Image by Lecturio.The pathophysiology of proximal RTA (type II) is impaired bicarbonate reabsorption Bicarbonate reabsorption Acid-Base Balance at the proximal tubule Proximal tubule The renal tubule portion that extends from the bowman capsule in the kidney cortex into the kidney medulla. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the u-shaped loop of henle. Tubular System.
Normal process of proximal tubule Proximal tubule The renal tubule portion that extends from the bowman capsule in the kidney cortex into the kidney medulla. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the u-shaped loop of henle. Tubular System HCO3– reabsorption:
Abnormal processes leading to proximal renal tubular acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis (type 2):
Complications:
Bicarbonate reabsorption in the
proximal tubule
Proximal tubule
The renal tubule portion that extends from the bowman capsule in the kidney cortex into the kidney medulla. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the u-shaped loop of henle.
Tubular System
CA
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)-IV: carbonic anhydrase IV
CA
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)-II: carbonic anhydrase II
The classic mechanism for most individuals with hyperkalemic RTA (i.e., diabetic nephropathy and mild-to-moderate 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) is hyporeninemic hypoaldosteronism Hypoaldosteronism Hypoaldosteronism is a hormonal disorder characterized by low levels of aldosterone. These low levels can be caused by decreased aldosterone production or a peripheral resistance to aldosterone. When hypoaldosteronism occurs as a result of an acquired decrease in renin production, the condition is more commonly referred to as renal tubular acidosis (RTA) type 4. Hypoaldosteronism.
Renal tubular acidoses often do not have a specific 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 and are only considered once metabolic acidosis Metabolic acidosis The renal system is responsible for eliminating the daily load of non-volatile acids, which is approximately 70 millimoles per day. Metabolic acidosis occurs when there is an increase in the levels of new non-volatile acids (e.g., lactic acid), renal loss of HCO3-, or ingestion of toxic alcohols. Metabolic Acidosis is discovered. Although some individuals are asymptomatic, many have significant symptoms caused by the underlying etiology of the RTA, rather than symptoms from the acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis itself.
Dental
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 of
rickets
Rickets
Disorders caused by interruption of bone mineralization manifesting as osteomalacia in adults and characteristic deformities in infancy and childhood due to disturbances in normal bone formation. The mineralization process may be interrupted by disruption of vitamin d; phosphorus; or calcium homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances.
Osteomalacia and Rickets seen in distal renal tubular
acidosis
Acidosis
A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up.
Respiratory Acidosis:
Rickets can be seen in individuals with distal renal tubular
acidosis
Acidosis
A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up.
Respiratory Acidosis, as it involves
calcium
Calcium
A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
Electrolytes wasting in 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.
Renal tubular acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis should be considered in the differential diagnosis of non–anion-gap metabolic acidosis Metabolic acidosis The renal system is responsible for eliminating the daily load of non-volatile acids, which is approximately 70 millimoles per day. Metabolic acidosis occurs when there is an increase in the levels of new non-volatile acids (e.g., lactic acid), renal loss of HCO3-, or ingestion of toxic alcohols. Metabolic Acidosis (NAGMA).
Once NAGMA is identified, consider the differential diagnosis:
Check 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 osmolal gap Osmolal gap Metabolic Acidosis (UOG) and/or 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 anion gap Anion gap Metabolic Acidosis (UAG).
To differentiate between the types of RTA, evaluate:
Serum bicarbonate Bicarbonate Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the ph of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity. Electrolytes level:
Urine pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance:
Serum potassium:
If the diagnosis is still unclear, a bicarbonate Bicarbonate Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the ph of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity. Electrolytes infusion test can be done:
Treatment for proximal RTA is more complicated than simply replacing bicarbonate Bicarbonate Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the ph of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity. Electrolytes:
Rationale:
Treatment involves a combination approach:
Treatment for hyperkalemic RTA differs significantly from that for the other forms of RTA, primarily in that oral bicarbonate Bicarbonate Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the ph of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity. Electrolytes therapy is not the 1st-line treatment.