Hypoaldosteronism

Etiology

Isolated Aldosteron Defects 

Isolated aldosterone defects can present as abnormalities in synthesis, release, or end-organ response. Each mechanism reflects a distinct underlying pathophysiology with unique congenital, acquired, or medication-induced contributors. Recognition of these categories supports accurate diagnosis and targeted treatment strategies.

Defective synthesis

Defective synthesis, known as hyperreninemic hypoaldosteronism, occurs when aldosterone production fails despite intact renin secretion. Congenital causes include aldosterone synthase deficiency types I and II (see Image. Aldosterone Synthase Enzyme). Acquired causes involve immaturity of aldosterone synthetic enzymes in very preterm infants, impaired function in critically ill patients, and delayed recovery of the suppressed adrenal gland following contralateral adrenalectomy. Several medications may also impair synthesis, including angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, heparin, cyclosporine, tacrolimus, and ketoconazole.

Defective release

Defective release, or hyporeninemic hypoaldosteronism, reflects reduced renin or angiotensin II production. This form frequently arises in acquired conditions, eg, type 4 renal tubular acidosis, chronic kidney disease, diabetic nephropathy, autonomic neuropathy, sickle cell disease, and HIV infection. Medications, including beta blockers, nonsteroidal anti-inflammatory drugs, and dopamine, can further suppress aldosterone release.

Aldosterone resistance

Aldosterone resistance develops when aldosterone production remains intact but target tissues fail to respond appropriately. Genetic forms include autosomal dominant pseudohypoaldosteronism type 1, autosomal recessive pseudohypoaldosteronism type 1, and Gordon syndrome (pseudohypoaldosteronism type II). Acquired resistance may occur in pediatric urinary tract infections, obstructive uropathy (pseudohypoaldosteronism type III), or following the downregulation of mineralocorticoid receptors after solid organ transplantation. Medication-induced resistance often results from using mineralocorticoid receptor antagonists (eg, spironolactone or eplerenone).

Adrenal Gland Failure

Adrenal gland failure results from impaired development, destruction of adrenal tissue, or suppression of adrenal function. The condition may arise through genetic, acquired, or medication-induced mechanisms, each contributing to reduced aldosterone production and subsequent mineralocorticoid deficiency. Genetic causes include congenital adrenal hyperplasia, in which enzyme defects disrupt steroidogenesis, and adrenal hypoplasia, where underdevelopment of the adrenal cortex limits hormone production. Both conditions present early in life and require careful management to prevent life-threatening salt-wasting crises.

Acquired adrenal failure often develops through direct destruction of adrenal tissue. Autoimmune processes remain a leading cause, while bilateral adrenal hemorrhage, infectious adrenalitis caused by pathogens, eg, tuberculosis or cytomegalovirus, and infiltrative conditions, including malignancy or amyloidosis, can also compromise adrenal integrity. Adrenal suppression may occur in the absence of structural damage, most commonly as a consequence of medications. Pharmacologic agents (eg, etomidate, mirotane) or prolonged administration of exogenous glucocorticoids or mineralocorticoids suppress endogenous hormone production, leaving patients vulnerable to adrenal insufficiency once therapy is withdrawn.

Epidemiology

Acquired causes of hypoaldosteronism are observed to be more prevalent than congenital causes. Acquired hypoaldosteronism in adults is frequently attributed to hyporeninemic hypoaldosteronism, which often results from chronic diseases or the use of medications that interfere with RAAS. Congenital causes of hypoaldosteronism predominantly occur in specific ethnic groups, which may reflect founder effects and population-specific mutations.[10][11] The most common cause of congenital isolated hypoaldosteronism is aldosterone synthase deficiency (ASD), resulting from mutations in the CYP11B2 gene.[12] Autosomal dominant pseudohypoaldosteronism type I is another rare congenital cause of hypoaldosteronism, and has a reported prevalence of less than 1 in 80,000 live births. 

Pathophysiology

Transient Pediatric Hypoaldosteronism

Preterm and very preterm neonates often develop a transient form of hypoaldosteronism that results from delayed maturation of adrenal synthetic pathways. These infants maintain intact renin stimulation, yet insufficient 11β-hydroxylase activity limits steroid conversion, and reduced mineralocorticoid receptor expression diminishes tissue responsiveness. This developmental immaturity contributes to impaired aldosterone-mediated regulation of sodium and potassium balance during the neonatal period. The condition generally resolves spontaneously as adrenal enzyme activity and receptor expression mature, with normalization occurring within the first few weeks to months of life.[13][14] Young individuals with urinary tract infections and obstructive uropathy may exhibit transient resistance to aldosterone, a condition known as pseudohypoaldosteronism III. The responsiveness of renal tubules to aldosterone activity typically improves following treatment of the underlying urologic condition.[15]

Persistent Pediatric Hypoaldosteronism

ASD is a hereditary condition linked to mutations in the CYP11B2 gene.[15] Over 40 mutations have been identified, most of which are either missense or nonsense. Autosomal dominant pseudohypoaldosteronism type 1 is caused by mutations in the NR3C2 gene, which encodes the mineralocorticoid receptor. At least 50 mutations have been associated with this condition, and the disease can be expressed with a single pathogenic allele. In contrast, autosomal recessive pseudohypoaldosteronism type 1 stems from loss-of-function mutations in the SCNN1A, SCNN1B, or SCNN1G genes, which encode the α, β, or γ subunits of epithelial sodium channels. This condition results in impaired assembly and expression of epithelial sodium channels.

Pseudohypoaldosteronism II is caused by mutations in the WNK1, WNK4, KLHL3, or CUL3 genes, resulting in gain-of-function mutations affecting the thiazide-sensitive sodium-chloride cotransporter (NCC). Ongoing research advances continue to uncover additional genes responsible for heritable hypoaldosteronism, eg, SEC61A1, which is involved in renin production.[16] These insights enhance our understanding of the molecular mechanisms underlying these conditions and may guide future therapeutic strategies.

Hyperreninemic Hypoaldosteronism

Hyperreninemic hypoaldosteronism occurs when impairment of aldosterone activity triggers a compensatory increase in plasma renin. Existing literature indicates that proinflammatory cytokines released during acute critical illness may suppress aldosterone production. A prospective study conducted in 2008 examined patients with liver cirrhosis who were hospitalized in the ICU. The findings demonstrated that disease severity and poor prognosis were positively correlated with elevated renin-to-aldosterone ratios and interleukin-6 levels.[17]

Unilateral adrenalectomy in patients with Conn syndrome can be associated with transient hyperreninemic hypoaldosteronism, attributable to the delayed recovery of the suppressed contralateral adrenal gland.[18][19] Angiotensin-converting enzyme inhibitors decrease angiotensin II production. Angiotensin receptor blockers (ARBs) block the stimulatory action of angiotensin II and prevent aldosterone secretion.

Conventional and low-molecular-weight heparin (LMWH) decrease aldosterone production and release; a similar effect is observed with cyclosporin and calcium channel blockers. LMWH diminishes the sensitivity of the zona glomerulosa to angiotensin II. Drugs like ketoconazole, which are also used in Cushing disease and other cancers, may affect all 3 axes of the adrenal synthetic pathways and diminish the action of angiotensin II. 

Hyporeninemic Hypoaldosteronism

Hyporeninemic hypoaldosteronism, also referred to as type 4 RTA, develops when renin output decreases, leading to inadequate aldosterone production. The decline in renin disrupts sodium and potassium homeostasis, resulting in clinical and biochemical features consistent with mineralocorticoid deficiency.[20] Renin production depends heavily on sympathetic stimulation. Defective release frequently arises from autonomic neuropathies and becomes aggravated by renal disease, medications affecting the RAA axis, production of inactive renin, diminished beta-receptor sensitivity, and impaired prostaglandin synthesis.

Patients most often present in the sixth to eighth decades of life, commonly with diabetes, mild to moderate renal impairment, and concurrent use of drugs that interfere with the RAA system. Clinical manifestations frequently include asymptomatic hyperkalemia, hyponatremia, and hyperchloremic normal anion gap acidosis, with laboratory evaluation showing low serum aldosterone. In patients with HIV, viral adrenalitis, nephropathy, and the use of trimethoprim can also contribute to this disorder.

Several medications influence the renin and aldosterone pathways. Beta-blockers decrease renin release, while NSAIDs inhibit cyclooxygenase and blunt prostaglandin-mediated stimulation of renin. Spironolactone both suppresses aldosterone biosynthesis and competitively antagonizes the mineralocorticoid receptor. Amiloride and trimethoprim block epithelial sodium channels in renal tubules, increasing sodium excretion and promoting potassium retention. Triamterene acts as a potassium-sparing diuretic by targeting aldosterone-independent ion-exchange sites in the distal convoluted tubule. Dopamine exerts a tonic inhibitory effect on aldosterone production. High doses used in critical care settings, as well as therapy with dopamine agonists, can further suppress aldosterone synthesis and precipitate clinically significant hypoaldosteronism under certain circumstances.

History and Physical

Children with autosomal dominant pseudohypoaldosteronism typically exhibit a milder phenotype, presenting primarily with renal hyponatremia, hyperkalemia, and metabolic acidosis during infancy. Many affected individuals improve with age and often become asymptomatic after early childhood.[21] In contrast, autosomal recessive pseudohypoaldosteronism usually involves multiorgan manifestations, including recurrent respiratory tract infections, skin rashes, and inspissated secretions from the meibomian glands, in addition to the classic features of hypoaldosteronism.[22] 

Prenatal detection of polyhydramnios may provide an early clue to autosomal recessive forms.[23] These children often require ongoing complex care and frequent hospitalizations, as symptoms persist throughout life. Patients with pseudohypoaldosteronism type III typically recover once underlying urinary tract infections or obstructive uropathy resolve.[15] In adult populations, careful review of medications remains essential, as rare cases of life-threatening hyperkalemia–induced arrhythmias have occurred in patients receiving conventional heparin.[24]

Clinicians should maintain a high index of suspicion in hospitalized or critically ill patients, as well as in those with diabetes, nephropathies, sickle cell disease, or HIV, to enable early recognition and prompt intervention. Adults undergoing adrenalectomy for unilateral aldosterone-producing adenoma (Conn syndrome) may experience prolonged suppression of the contralateral zona glomerulosa. Risk factors for delayed recovery include advanced age, long-standing hypertension, large adenoma size, preoperative and postoperative renal dysfunction, and preoperative nonsteroidal anti-inflammatory drug use.[25]

Evaluation

Diagnostic Laboratory Studies

Early and accurate diagnosis of infants presenting with a salt-wasting crisis depends on obtaining a blood sample while the patient is clinically or biochemically symptomatic and before initiating treatment. This specimen, referred to as the "critical sample," allows laboratory testing to avoid confounding effects from therapy. One sample aliquot is analyzed for serum electrolytes, aldosterone, 17-hydroxyprogesterone (17-OHP), and plasma renin activity or concentration. This initial panel guides further diagnostic evaluation.

A second aliquot is reserved for confirmatory testing, which may include serum cortisol and adrenocorticotropic hormone (ACTH) in suspected congenital adrenal hyperplasia, 18-hydroxycortisosterone (18-OHC)—low to normal in type 1 ASD and elevated in type 2 ASD—and urinary tetrahydro-aldosterone, decreased in type 1 and low-normal to normal in type 2 ASD. In infants with ASD but normal aldosterone concentrations, the plasma aldosterone concentration/plasma renin concentration ratio helps clarify the diagnosis of primary hypoaldosteronism.[26]

Some infants with pseudohypoaldosteronism may have falsely low aldosterone levels on assay testing, a phenomenon referred to as the “hook effect,” where very elevated aldosterone levels can paradoxically result in low levels on certain assay methods, potentially resulting in a misdiagnosis. The assay should be repeated with progressively diluted samples to avoid this and achieve high aldosterone levels accurately. Aldosterone measurement using serial sample dilutions can reveal markedly elevated levels, confirming the diagnosis of pseudohypoaldosteronism and preventing misdiagnosis as an ASD.[27]

Key biochemical tests that may be performed in the evaluation of hypoaldosteroneism include:

• Serum electrolytes
• Serum and urine aldosterone
• Serum cortisol and plasma ACTH
• Serum 17-OHP
• 18-OHC (low to normal in type 1 and high in type 2 aldosterone synthase deficiency)
• Urinary tetrahydroaldosterone, the metabolite of aldosterone (decreased in type 1 and low normal or normal in type 2 aldosterone synthase deficiency)
• Plasma renin activity or plasma renin concentration 
• Plasma aldosterone concentration/plasma renin concentration ratio
• Plasma aldosterone concentration/potassium ratio (in chronic kidney disease, <10 ng/dL is suggestive of hypoaldosteronism and >10 ng/dL is suggestive of renal aldosterone resistance) [28]
• Serum creatinine and estimated glomerular filtration rate 
• Molecular genetic studies, including gene sequencing (see Image. Genetics of Hypoaldosteronism)

Treatment / Management

Management Approach in Pediatric Populations

For pediatric individuals presenting with a salt-wasting crisis due to ASD, autosomal dominant pseudohypoaldosteronism, or autosomal recessive pseudohypoaldosteronism, the initial management entails aggressive rehydration with isotonic fluids. Before a definitive diagnosis of hypoaldosteronism is made, after drawing a critical sample of blood, patients should be empirically treated for presumed congenital adrenal hyperplasia with intravenous hydrocortisone in stress doses. This also has adequate mineralocorticoid activity and will tide over the crises. If 17-OHP levels are within normal range and a diagnosis of ASD has been made, fludrocortisone can be substituted orally for hydrocortisone after the infant stabilizes. Initial dosing of fludrocortisone for patients with ASD starts at 150 µg/m² body surface area. The younger the child, the greater the doses of fludrocortisone because of drug insensitivity in infants and young children.

Fludrocortisone is ineffective as maintenance therapy in autosomal dominant pseudohypoaldosteronism and autosomal recessive pseudohypoaldosteronism due to end-organ resistance. In these cases, the management approach focuses on supportive care, with aggressive correction of hyponatremia and hyperkalemia using high-dose sodium chloride supplementation and cation exchange resins. In severe or refractory cases, peritoneal dialysis, thiazide diuretics, and indomethacin may be useful.[29][30](B3)

Etiology-Guided Management

In Conn syndrome, discontinuing spironolactone and correction of any volume expansion for at least 3 days preoperatively is recommended. Following adrenalectomy, hypoaldosteronism is managed with fludrocortisone. Some patients may require extended support until their adrenal function fully recovers from suppression.[31][32]

Renal transplant individuals treated with calcineurin inhibitors present with hyperkalemia secondary to hypoaldosteronism and respond favorably to a low dose of fludrocortisone.[33] In type 4 renal tubular acidosis, fludrocortisone is useful in reducing hyperkalemia, but caution is required as sodium retention, fluid overload, and precipitation of congestive heart failure are potential adverse effects. Adding a loop diuretic, or even better, thiazides that block the sodium-chloride cotransporter in the distal renal tubules, may be necessary. Precipitating medications, eg, nonsteroidal anti-inflammatory drugs and potassium-sparing diuretics, should be carefully reviewed and discontinued.(B2)

Differential Diagnosis

Hypoaldosteronism can be differentiated from global adrenal failure by the presence of genital ambiguity in female infants and a high 17-OHP in both sexes in congenital adrenal hyperplasia (CAH). Addison disease in older children and adults will have decreased serum cortisol and increased ACTH, present dramatically, and have physical findings like hyperpigmentation. Infants with CAH typically present with salt-wasting and hyperpigmentation, while cortisol deficiency usually develops later. A cosyntropin stimulation test may be necessary to confirm cortisol deficiency. Deficiency of cholesterol side-chain cleaving enzymes produces deficiencies in all 3 adrenal axes. Thus, salt-wasting, low cortisol, and ambiguous genitalia in male infants are seen.

Decreased aldosterone and increased plasma renin concentration are features of aldosterone synthase deficiency. In contrast, pseudohypoaldosteronism is characterized by a very high plasma renin concentration and aldosterone, although both conditions exhibit low sodium, high potassium, and acidosis. A definitive diagnosis of biosynthetic defects causing hypoaldosteronism is typically made through gene sequencing.[12]

A preoperative aldosterone contralateral suppression index (see Image. Adrenal Venous Sampling) during adrenal venous sampling is the ratio of aldosterone to cortisol in the ipsilateral adrenal vein divided by a similar ratio in the external iliac vein. Patients with a contralateral suppression index of less than 0.47 are at risk for prolonged adrenal suppression and require close monitoring of serum potassium after unilateral adrenalectomy for Conn syndrome.

In critically ill individuals, hypoaldosteronism often lacks clinical significance because elevated cortisol levels activate the mineralocorticoid receptor, compensating for reduced aldosterone activity. Certain conditions, however, present with low aldosterone levels secondary to sodium retention, hypertension, hypokalemia, suppressed plasma renin concentration, and extracellular volume expansion. Based on these characteristic features, these states must be distinguished from salt-wasting causes of hypoaldosteronism. Examples include Liddle syndrome and the syndrome of mineralocorticoid excess, caused by the inhibition of 11β-hydroxysteroid dehydrogenase type 2. Gordon syndrome represents another distinct entity, in which patients exhibit hypertension accompanied by hyperkalemia, hyperchloremic acidosis, and suppressed renin levels, all resulting from chronic volume expansion. Accurate differentiation of these conditions is essential to guide appropriate management and avoid unnecessary interventions.

Prognosis

The prognosis of the congenital forms depends on the subtype. Patients with aldosterone synthase deficiency and autosomal dominant pseudohypoaldosteronism can be weaned off medications and even go into remission if identified early and promptly treated. Older children who are inadequately treated have retarded growth or failure to thrive, but adequately treated children can grow normally and have a good catch-up growth.

Autosomal recessive pseudohypoaldosteronism patients, as a rule, do not improve and require close monitoring. Pseudohypoaldosteronism III patients will be cured once their primary renal infection or obstruction is resolved. Diligent management of medications causing hypoaldosteronism will reduce morbidity considerably. Most patients with hypoaldosteronism postadrenalectomy for Conn syndrome resolve early, while some at high risk may need longer than 6-month surveillance.

Complications

In patients treated for hypoaldosteronism, overdosage with fludrocortisone can cause fluid retention, low potassium, significantly suppressed plasma renin concentration, and, ultimately, can even precipitate congestive heart failure. Less severe but clinically significant adverse effects include constipation due to increased colonic mucosal sodium and water reabsorption, weight gain due to fluid retention, and muscle weakness due to hypokalemia. Dosing should be titrated to plasma renin concentration levels in the upper limits of the normal range. Undertreated children will have poor growth. When the diagnosis is delayed in infants with severe disease, mortality is increased.