Hypoaldosteronism is a rare condition caused by the deficiency of the hormone aldosterone. It can either be congenital or acquired which, in turn, can be primary or secondary and can be associated with elevated or diminished levels of renin. The disorder is characterized by hyperkalemia and metabolic acidosis. Diagnosis is based on laboratory tests.
Hypoaldosteronism is a rare disorder which is usually asymptomatic. It can either be congenital/primary  or can be secondary to renal dysfunction, multiple myeloma, diabetes, drugs like angiotensin-converting enzyme (ACE) inhibitors, debilitating diseases, lead toxicity and enzyme defects in aldosterone synthesis .
Patients with mild hyperkalemia are often asymptomatic but those with severe hyperkalemia may present with fatigue, asthenia, nausea, vomiting, dyspnea (Kussmaul respiration), palpitations, angina, myopathies, flaccid paralysis, paralytic ileus, and cardiac arrhythmias . Clinical features of underlying conditions like edema or pathological fractures or autoimmune disorders can also be noticed.
Congenital hypoaldosteronism is due to the deficiency of the enzyme aldosterone synthase and it is inherited in an autosomal recessive pattern. Two types of biochemically different aldosterone deficiencies have been reported: corticosterone methyl oxidase (CMO) deficiency type I and type II . Clinically both the disorders present with failure to thrive, growth restriction and depletion of sodium with elevated levels of serum potassium .
Hypoaldosteronism is often diagnosed during laboratory tests but it should be suspected in patients with end-stage or chronic renal disease. Physicians should inquire about the chronic use of analgesics or ACE inhibitors, occupational or recreational exposure to either lead or moonshine (alcohol) respectively, obstructive uropathy, and an abnormal appetite (pica) for paint/mud. History of diseases like diabetes or autoimmune disorders like systemic lupus erythematosus (SLE) should also be elicited. Physical examination may reveal non-specific findings such as hypertension and rarely Kussmaul type of respiration can be noted.
Laboratory tests are ordered based on history and physical examination focusing on complete blood count, platelet count, serum electrolytes, blood sugar levels, renal function tests, urinalysis and serology tests to determine underlying renal disorders like SLE, multiple myeloma, hepatitis and human immunodeficiency virus (HIV) infection. Fractional excretion of potassium and the gradient of transtubular potassium is calculated from a potassium, creatinine, and urine osmolar spot test. Extremely low levels in the presence of hyperkalemia are suggestive of hypoaldosteronism. Urinary pH analysis helps to differentiate between type I and type IV renal tubular acidosis and a cosyntropin test is indicated in cases suspected to have adrenal insufficiency. If hyporeninemic hypoaldosteronism is suspected then a trial of oral fludrocortisone is given to confirm the diagnosis. The potassium levels normalize within two days of administration of fludrocortisone in patients with hyporeninemic hypoaldosteronism .
Patients with suspected obstructive uropathy should undergo ultrasonography and a renal biopsy may be required for definitive diagnosis in patients with an early-stage chronic renal disease.