Hypoaldosteronism overview: Difference between revisions
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{{Hypoaldosteronism}} | {{Hypoaldosteronism}} | ||
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==Overview== | ==Overview== | ||
Hypoaldosteronism is defined as decreased levels of the [[hormone]] [[aldosterone]] or a [[resistance]] of the target tissue to the actions of [[aldosterone]]. | |||
There are several causes for decreased levels of aldosterone, including [[kidney]] disorders, [[adrenal insufficiency]], [[congenital adrenal hyperplasia]], and medications such as | |||
There are several causes for | [[ACE inhibitors]], [[Angiotensin II receptor antagonist|angiotensin receptor blockers]], [[NSAIDs]] and [[Immunosuppressive drug|calcineurin inhibitors]]. [[Mutation]] in the [[mineralocorticoid receptor]] [[gene]] (NR3C2) may lead to resistance to the actions of the [[aldosterone]]. Hypoaldosteronism results in [[hyperkalemia]], which can be a serious medical condition. [[Hyponatremia]] is unusual in isolated aldosterone deficiency as under normal conditions [[cortisol]] inhibits [[antidiuretic hormone]] secretion. In patients with adrenal insufficiency as a cause of hypoaldosteronism, decrease in [[cortisol]], [[aldosterone]], and [[androgen]] levels may lead to [[hyponatremia]]. Hypoaldosteronism may be classified into two categories depending on the level of [[Plasma renin activity|plasma renin]] and depending on the level of [[aldosterone]]. The most common cause of hypoaldosteronism is [[diabetic nephropathy]], [[acute glomerulonephritis]], [[tuberculosis]], [[hemorrhage]], [[infarction]], [[sarcoidosis]], [[AIDS]], [[CMV]], and [[Addison's disease]]. Less common causes of hypoaldosteronism include [[sarcoidosis]], [[amyloidosis]], [[fungal infections]], [[AIDS]] complications, and [[hemochromatosis]].Hypoaldosteronism must be differentiated from other diseases that cause [[hypotension]] and [[muscle weakness]]. Common risk factors in the development of hypoaldosteronism include [[diabetes mellitus]], [[sickle cell anemia]], [[HIV]], [[graves' disease]], [[hypoparathyroidism]], [[hypopituitarism]], [[myasthenia gravis]], and [[pernicious anemia]]. If left untreated, hypoaldosteronism may lead to [[hyperkalemia]] and severe muscle weakness. Common complications of hypoaldosteronism include [[hyperkalemia]], [[metabolic acidosis]], [[hypotension]], [[hypovolemia]] and [[hyponatremia]]. Prognosis of hypoaldosteronism is generally good for patients who receive treatment. | ||
==Historical Perspective== | ==Historical Perspective== | ||
Hypoaldosteronism was first described by an American physician Hudson JB in the year 1956. Later on, in the year 1964, physicians Viser and Ulick gave a description on isolated and congenital hypoaldosteronism respectively. | |||
==Classification== | ==Classification== | ||
Hypoaldosteronism may be classified on the basis of [[Plasma renin activity|plasma renin]] levels into hyporeninemic hypoaldosteronism and hyperreninemic hypoaldosteronism. Hypoaldosteronism can also be classified on the basis of plasma [[aldosterone]] levels into [[aldosterone]] deficiency and [[aldosterone]] resistance. | |||
==Pathophysiology== | ==Pathophysiology== | ||
Hypoaldosteronism is defined as decreased levels of the [[hormone]] [[aldosterone]] or a [[resistance]] of the target tissue to the actions of [[aldosterone]]. Hypoaldosteronism from decreased production is seen in conditions such as congenital isolated hypoaldosteronism, [[Primary adrenal insufficiency|primary adrenal insufficiency,]] [[diabetic nephropathy]], [[critical illness]], and [[drugs]] such as [[ACE inhibitor|ACE inhibitors]], [[NSAIDs]] and [[Calcineurin inhibitor|calcineurin inhibitors]]. [[Resistance]] of the target tissue to the actions of [[aldosterone]] is seen with [[mineralocorticoid receptor]] defects (seen in [[pseudohypoaldosteronism]]) and with [[drugs]] such as [[potassium-sparing diuretics]] and [[trimethoprim]]. Hypoaldosteronism results in reduced [[reabsorption]] of [[sodium]] in the [[principal cells]] of [[Cortical collecting duct|cortical collecting tubules]] (CCT). This leads to decreased [[excretion]] of [[potassium]] ([[hyperkalemia]]) and mild non-anion gap [[metabolic acidosis]]. On gross pathology, [[adrenal glands]] may be irregularly shrunken or [[hyperplastic]]. | |||
==Causes== | ==Causes== | ||
The common causes of hypoaldosteronism include [[diabetic nephropathy]], [[acute glomerulonephritis]], [[tuberculosis]], [[hemorrhage]], [[infarction]], [[sarcoidosis]], [[AIDS]], [[CMV]] infection, and [[Addison's disease]]. Less common causes of hypoaldosteronism include [[sarcoidosis]], [[amyloidosis]], [[fungal infections]], [[AIDS]] complications, and [[hemochromatosis]]. | |||
==Differentiating | ==Differentiating Hypoaldosteronism from Other Diseases== | ||
Hypoaldosteronism must be differentiated from other diseases that cause [[hypotension]] and [[muscle weakness]] such as [[Addison's disease]], [[myopathies]], [[celiac disease]], [[Peutz-Jeghers syndrome]], [[anorexia nervosa]], [[Syndrome of inappropriate antidiuretic hormone|syndrome of inappropriate anti-diuretic hormone (SIADH)]], [[neurofibromatosis]], [[porphyria cutanea tarda]], salt-depletion [[nephritis]] and [[bronchogenic carcinoma]]. In addition, measurement of [[Plasma renin activity|plasma renin activity (PRA)]], serum [[aldosterone]], and serum [[cortisol]] is used to [[differentiate]] among various subtypes of hypoaldosteronism. | |||
==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
In hospitalized [[patients]], the [[incidence]] of hypoaldosteronism is 3000 per 100,000 individuals. The [[prevalence]] of hypoaldosteronism in United states is estimated to be 200,000 cases. Hypoaldosteronism is most commonly seen in middle-aged and older individuals. Both men and women are affected equally. Hypoaldosteronism is more prevalent in African-American, Native Americans, and Hispanics. | |||
==Risk Factors== | ==Risk Factors== | ||
Common risk factors in the development of hypoaldosteronism include [[diabetes mellitus]], [[sickle cell anemia]], [[HIV]], [[graves' disease]], [[hypoparathyroidism]], [[hypopituitarism]] [[myasthenia gravis]], and [[pernicious anemia]]. Other less common risk factors include [[multiple myeloma]], [[SLE|SLE-associated renal disease]] and [[Wolman's disease|Wolmans disease]]. | |||
==Screening== | ==Screening== | ||
There is insufficient evidence to recommend routine [[Screening (medicine)|screening]] for hypoaldosteronism. | |||
==Natural History, Complications, and Prognosis== | ==Natural History, Complications, and Prognosis== | ||
If left untreated, hypoaldosteronism leads to [[hyperkalemia]] which can alter the function of [[Electrical conduction system of the heart|cardiac conduction pathways]]. Depending upon the severity of hypoaldosteronism, [[hyperkalemia]] can be a life threatening condition. When [[serum potassium]] rises above ≥ 9 mEq/L, [[hyperkalemia]] may lead to [[ventricular fibrillation]], [[PEA]] and even [[cardiac arrest]]. Common [[complications]] of hypoaldosteronism include [[hyperkalemia]], [[metabolic acidosis]], [[hypotension]], [[hypovolemia]] and [[hyponatremia]]. Depending on the extent of the [[hyperkalemia]] and underlying [[renal]] or [[Adrenal gland|adrenal]] condition at the time of [[diagnosis]], the [[prognosis]] of [[hypoaldosteronism]] may vary. Prognosis of hypoaldosteronism is generally good for [[patients]] who receive treatment. | |||
==Diagnosis== | ==Diagnosis== | ||
===Diagnostic Criteria=== | ===Diagnostic Criteria=== | ||
There is no established [[criteria]] for the [[diagnosis]] of hypoaldosteronism. However, a positive history of [[hypotension]], [[muscle weakness]] and [[fatigue]] should raise suspicion for hypoaldosteronism. These [[patients]] should first be tested for [[serum]] [[potassium]] levels, [[Plasma renin activity|plasma renin activity (PRA)]], serum [[aldosterone]], and serum [[cortisol]]. [[Asymptomatic]] hypoaldosteronism can also be discovered on routine [[laboratory]] evaluations. | |||
===History and Symptoms=== | ===History and Symptoms=== | ||
Hypoaldosteronism often has a gradual onset. Patients of hypoaldosteronism should be enquired about the use of [[drugs]] that can alter [[aldosterone]] production or function. These drugs include [[ACE inhibitors]], [[angiotensin receptor blockers]] and [[NSAIDs]]. The most common [[symptoms]] of hypoaldosteronism include [[fatigue]], [[muscle weakness]], and [[Hypotension|low blood pressure]]. Other less common [[symptoms]] of hypoaldosteronism include [[hyperpigmentation]], [[gastrointestinal]] disturbances, and [[abdominal pain]]. | |||
===Physical Examination=== | ===Physical Examination=== | ||
[[Patients]] with hypoaldosteronism usually appear [[Fatigue|fatigued]]. [[Physical examination]] of [[patients]] with hypoaldosteronism is usually unremarkable, unless there is severe [[hyperkalemia]]. Increased level of serum [[potassium]] level may present with muscle [[tenderness]], [[hyporeflexia]]/[[areflexia]] and [[cardiac arrhythmias]]. The physical exam may also represent findings of underlying condition such as [[chronic kidney disease]] or [[diabetic nephropathy]]. | |||
===Laboratory Findings=== | ===Laboratory Findings=== | ||
[[Laboratory]] findings consistent with the [[diagnosis]] of hypoaldosteronism include [[hyperkalemia]] and mild non-anion gap [[metabolic acidosis]]. Other [[Laboratory|lab]] findings include [[hyponatremia]], decreased [[aldosterone]] level, and variable amounts of [[plasma renin activity]] (depends upon the underlying condition). | |||
===Electrocardiogram=== | ===Electrocardiogram=== | ||
In hypoaldosteronism there are no specific [[ECG]] findings. However, hypoaldosteronism predisposes to [[ | In hypoaldosteronism there are no specific [[ECG]] findings. However, hypoaldosteronism predisposes to [[hyperkalemia]] (decreased [[renal]] excretion) and occasional [[hyponatremia]] (from decreased [[renal]] absorption). [[Hyperkalemia]] leads to [[Depression (physiology)|depression]] of [[SA node]] and [[Conduction System|conduction pathways]] such as [[AV node]] and [[His-Purkinje system]] causing [[bradycardia]] and [[Conduction block|conduction blocks]]. On the other hand, severe [[hyponatremia]] may present with [[ST segment elevation]] mimicking [[acute myocardial infarction]]. | ||
===X-ray=== | ===X-ray=== | ||
There are no [[x-ray]] findings associated with hypoaldosteronism. | |||
===Ultrasound=== | ===Ultrasound=== | ||
There are no specific findings of hypoaldosteronism on [[ultrasound]]. However, [[ultrasound]] may be helpful in the [[diagnosis]] of hypoaldosteronism from [[disorders]] of [[renal]] or [[adrenal glands]]. [[Chronic kidney disease]] is an important [[Causes|cause]] of hypoaldosteronism and on [[ultrasound]] presents with reduced [[renal]] length, reduced [[Renal cortex|renal cortical]] thickness, and with poor visibility of the [[renal pyramids]] and the [[renal sinus]]. Hypoaldosteronism from [[adrenal insufficiency]] may present with irregularly shrunken [[adrenal glands]], adrenal [[nodules]], and [[signs]] of [[calcium]] deposits. | |||
===CT scan=== | ===CT scan=== | ||
There are no [[CT|CT scan]] findings associated with hypoaldosteronism. A [[CT]] scan is not routinely done for the [[diagnosis]] of hypoaldosteronism. | |||
===MRI=== | ===MRI=== | ||
There are no specific [[MRI]] findings associated with hypoaldosteronism. | |||
===Other Imaging Findings=== | ===Other Imaging Findings=== | ||
There are no other [[imaging]] findings associated with hypoaldosteronism. | |||
===Other Diagnostic Studies=== | ===Other Diagnostic Studies=== | ||
There are no other [[diagnostic]] studies associated with hypoaldosteronism. | |||
==Treatment== | ==Treatment== | ||
===Medical Therapy=== | ===Medical Therapy=== | ||
The mainstay of treatment for hypoaldosteronism depends upon the level of plasma [[potassium]]. Prompt [[ECG]] is advised in all [[patients]] suspected of hypoaldosteronism as [[hyperkalemia]] may lead to [[Conduction disorders|cardiac conduction defects]] and life threatening [[arrhythmias]]. Patients with no [[ECG]] changes and moderate [[hyperkalemia]] (6.5–7.5 mmol/l) require only monitoring. Patients with severe [[hyperkalemia]] (>7.5 mmol/l) are treated with [[emergency]] measures for [[hyperkalemia]] ([[calcium]], [[insulin]], β<sub>2</sub> agonist or cation resins) and [[fludrocortisone]]. Depending upon the [[volume status]], [[patients]] may be treated with either [[Normal saline|0.9% normal saline]] ([[hypovolemia]]) or [[furosemide]] ([[Hypervolemia|hypervolemic]]). | |||
===Surgery=== | ===Surgery=== | ||
[[Surgery|Surgical]] intervention is not recommended for the management of hypoaldosteronism. | |||
===Primary Prevention=== | ===Primary Prevention=== | ||
There are no established measures for the [[primary prevention]] of hypoaldosteronism. | |||
===Secondary Prevention=== | ===Secondary Prevention=== | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Akshun Kalia M.B.B.S.[2]
Overview
Hypoaldosteronism is defined as decreased levels of the hormone aldosterone or a resistance of the target tissue to the actions of aldosterone. There are several causes for decreased levels of aldosterone, including kidney disorders, adrenal insufficiency, congenital adrenal hyperplasia, and medications such as ACE inhibitors, angiotensin receptor blockers, NSAIDs and calcineurin inhibitors. Mutation in the mineralocorticoid receptor gene (NR3C2) may lead to resistance to the actions of the aldosterone. Hypoaldosteronism results in hyperkalemia, which can be a serious medical condition. Hyponatremia is unusual in isolated aldosterone deficiency as under normal conditions cortisol inhibits antidiuretic hormone secretion. In patients with adrenal insufficiency as a cause of hypoaldosteronism, decrease in cortisol, aldosterone, and androgen levels may lead to hyponatremia. Hypoaldosteronism may be classified into two categories depending on the level of plasma renin and depending on the level of aldosterone. The most common cause of hypoaldosteronism is diabetic nephropathy, acute glomerulonephritis, tuberculosis, hemorrhage, infarction, sarcoidosis, AIDS, CMV, and Addison's disease. Less common causes of hypoaldosteronism include sarcoidosis, amyloidosis, fungal infections, AIDS complications, and hemochromatosis.Hypoaldosteronism must be differentiated from other diseases that cause hypotension and muscle weakness. Common risk factors in the development of hypoaldosteronism include diabetes mellitus, sickle cell anemia, HIV, graves' disease, hypoparathyroidism, hypopituitarism, myasthenia gravis, and pernicious anemia. If left untreated, hypoaldosteronism may lead to hyperkalemia and severe muscle weakness. Common complications of hypoaldosteronism include hyperkalemia, metabolic acidosis, hypotension, hypovolemia and hyponatremia. Prognosis of hypoaldosteronism is generally good for patients who receive treatment.
Historical Perspective
Hypoaldosteronism was first described by an American physician Hudson JB in the year 1956. Later on, in the year 1964, physicians Viser and Ulick gave a description on isolated and congenital hypoaldosteronism respectively.
Classification
Hypoaldosteronism may be classified on the basis of plasma renin levels into hyporeninemic hypoaldosteronism and hyperreninemic hypoaldosteronism. Hypoaldosteronism can also be classified on the basis of plasma aldosterone levels into aldosterone deficiency and aldosterone resistance.
Pathophysiology
Hypoaldosteronism is defined as decreased levels of the hormone aldosterone or a resistance of the target tissue to the actions of aldosterone. Hypoaldosteronism from decreased production is seen in conditions such as congenital isolated hypoaldosteronism, primary adrenal insufficiency, diabetic nephropathy, critical illness, and drugs such as ACE inhibitors, NSAIDs and calcineurin inhibitors. Resistance of the target tissue to the actions of aldosterone is seen with mineralocorticoid receptor defects (seen in pseudohypoaldosteronism) and with drugs such as potassium-sparing diuretics and trimethoprim. Hypoaldosteronism results in reduced reabsorption of sodium in the principal cells of cortical collecting tubules (CCT). This leads to decreased excretion of potassium (hyperkalemia) and mild non-anion gap metabolic acidosis. On gross pathology, adrenal glands may be irregularly shrunken or hyperplastic.
Causes
The common causes of hypoaldosteronism include diabetic nephropathy, acute glomerulonephritis, tuberculosis, hemorrhage, infarction, sarcoidosis, AIDS, CMV infection, and Addison's disease. Less common causes of hypoaldosteronism include sarcoidosis, amyloidosis, fungal infections, AIDS complications, and hemochromatosis.
Differentiating Hypoaldosteronism from Other Diseases
Hypoaldosteronism must be differentiated from other diseases that cause hypotension and muscle weakness such as Addison's disease, myopathies, celiac disease, Peutz-Jeghers syndrome, anorexia nervosa, syndrome of inappropriate anti-diuretic hormone (SIADH), neurofibromatosis, porphyria cutanea tarda, salt-depletion nephritis and bronchogenic carcinoma. In addition, measurement of plasma renin activity (PRA), serum aldosterone, and serum cortisol is used to differentiate among various subtypes of hypoaldosteronism.
Epidemiology and Demographics
In hospitalized patients, the incidence of hypoaldosteronism is 3000 per 100,000 individuals. The prevalence of hypoaldosteronism in United states is estimated to be 200,000 cases. Hypoaldosteronism is most commonly seen in middle-aged and older individuals. Both men and women are affected equally. Hypoaldosteronism is more prevalent in African-American, Native Americans, and Hispanics.
Risk Factors
Common risk factors in the development of hypoaldosteronism include diabetes mellitus, sickle cell anemia, HIV, graves' disease, hypoparathyroidism, hypopituitarism myasthenia gravis, and pernicious anemia. Other less common risk factors include multiple myeloma, SLE-associated renal disease and Wolmans disease.
Screening
There is insufficient evidence to recommend routine screening for hypoaldosteronism.
Natural History, Complications, and Prognosis
If left untreated, hypoaldosteronism leads to hyperkalemia which can alter the function of cardiac conduction pathways. Depending upon the severity of hypoaldosteronism, hyperkalemia can be a life threatening condition. When serum potassium rises above ≥ 9 mEq/L, hyperkalemia may lead to ventricular fibrillation, PEA and even cardiac arrest. Common complications of hypoaldosteronism include hyperkalemia, metabolic acidosis, hypotension, hypovolemia and hyponatremia. Depending on the extent of the hyperkalemia and underlying renal or adrenal condition at the time of diagnosis, the prognosis of hypoaldosteronism may vary. Prognosis of hypoaldosteronism is generally good for patients who receive treatment.
Diagnosis
Diagnostic Criteria
There is no established criteria for the diagnosis of hypoaldosteronism. However, a positive history of hypotension, muscle weakness and fatigue should raise suspicion for hypoaldosteronism. These patients should first be tested for serum potassium levels, plasma renin activity (PRA), serum aldosterone, and serum cortisol. Asymptomatic hypoaldosteronism can also be discovered on routine laboratory evaluations.
History and Symptoms
Hypoaldosteronism often has a gradual onset. Patients of hypoaldosteronism should be enquired about the use of drugs that can alter aldosterone production or function. These drugs include ACE inhibitors, angiotensin receptor blockers and NSAIDs. The most common symptoms of hypoaldosteronism include fatigue, muscle weakness, and low blood pressure. Other less common symptoms of hypoaldosteronism include hyperpigmentation, gastrointestinal disturbances, and abdominal pain.
Physical Examination
Patients with hypoaldosteronism usually appear fatigued. Physical examination of patients with hypoaldosteronism is usually unremarkable, unless there is severe hyperkalemia. Increased level of serum potassium level may present with muscle tenderness, hyporeflexia/areflexia and cardiac arrhythmias. The physical exam may also represent findings of underlying condition such as chronic kidney disease or diabetic nephropathy.
Laboratory Findings
Laboratory findings consistent with the diagnosis of hypoaldosteronism include hyperkalemia and mild non-anion gap metabolic acidosis. Other lab findings include hyponatremia, decreased aldosterone level, and variable amounts of plasma renin activity (depends upon the underlying condition).
Electrocardiogram
In hypoaldosteronism there are no specific ECG findings. However, hypoaldosteronism predisposes to hyperkalemia (decreased renal excretion) and occasional hyponatremia (from decreased renal absorption). Hyperkalemia leads to depression of SA node and conduction pathways such as AV node and His-Purkinje system causing bradycardia and conduction blocks. On the other hand, severe hyponatremia may present with ST segment elevation mimicking acute myocardial infarction.
X-ray
There are no x-ray findings associated with hypoaldosteronism.
Ultrasound
There are no specific findings of hypoaldosteronism on ultrasound. However, ultrasound may be helpful in the diagnosis of hypoaldosteronism from disorders of renal or adrenal glands. Chronic kidney disease is an important cause of hypoaldosteronism and on ultrasound presents with reduced renal length, reduced renal cortical thickness, and with poor visibility of the renal pyramids and the renal sinus. Hypoaldosteronism from adrenal insufficiency may present with irregularly shrunken adrenal glands, adrenal nodules, and signs of calcium deposits.
CT scan
There are no CT scan findings associated with hypoaldosteronism. A CT scan is not routinely done for the diagnosis of hypoaldosteronism.
MRI
There are no specific MRI findings associated with hypoaldosteronism.
Other Imaging Findings
There are no other imaging findings associated with hypoaldosteronism.
Other Diagnostic Studies
There are no other diagnostic studies associated with hypoaldosteronism.
Treatment
Medical Therapy
The mainstay of treatment for hypoaldosteronism depends upon the level of plasma potassium. Prompt ECG is advised in all patients suspected of hypoaldosteronism as hyperkalemia may lead to cardiac conduction defects and life threatening arrhythmias. Patients with no ECG changes and moderate hyperkalemia (6.5–7.5 mmol/l) require only monitoring. Patients with severe hyperkalemia (>7.5 mmol/l) are treated with emergency measures for hyperkalemia (calcium, insulin, β2 agonist or cation resins) and fludrocortisone. Depending upon the volume status, patients may be treated with either 0.9% normal saline (hypovolemia) or furosemide (hypervolemic).
Surgery
Surgical intervention is not recommended for the management of hypoaldosteronism.
Primary Prevention
There are no established measures for the primary prevention of hypoaldosteronism.
Secondary Prevention
Effective measures for the secondary prevention of hypoaldosteronism include liberal salt intake of 4gm/day (to increase plasma sodium concentration), decreasing potassium intake and avoidance of drugs that affects renin angiotensin aldosterone system (RAAS) such as ACE inhibitors, ARBs, potassium sparing diuretics and β-Adrenergic receptor blockers.