Aldosteronism is a syndrome caused by excessive and inappropriate aldosterone production.

Epidemiology

• Prevalence - 5-15% of unselected hypertensive patients
• Age - 30-50 years
• Sex - F:M is 2:1

Etiologies

• Bilateral cortical nodular hyperplasia
• Aldosterone-producing tumor (Conn’s Syndrome)
• Adrenal carcinoma, rare in the general population

Pathophysiology

• Hypersecretion of aldosterone increases the renal distal tubular exchange of sodium for potassium and hydrogen
• Progressive depletion of potassium and hydrogen leads to hypokalemia and acidosis
• Excess sodium reabsorption leads to hypertension
• Classification
  • Primary - excess aldosterone secretion by the adrenal glands
  • Secondary - renin-mediated secretion
    • Seen in congestive heart failure, nephritic syndrome, cirrhosis, renal artery hypertension, severe arteriolar nephrosclerosis, rare renin-secreting tumors

Clinical Presentation

• Constitutional - weakness, fatigue
• Renal - polyuria, proteinuria, renal failure
• Cardiac - hypertension, cardiac hypertrophy
• Edema - rarely exists

Treatment

• Often involves surgical excision of the tumor
• Aldosterone antagonists (spironolactone) may be successful therapy

Diagnosis

• Indications for testing
  • Suggested by persistent hypokalemia and hypertension in patients with normal sodium intake, absence of edema and not currently receiving diuretics (from electrolyte testing)
    • Hypokalemia - often severe; although patients may have normokalemia, particularly if already taking potassium-sparing diuretics
    • Impaired urinary concentration
    • Metabolic alkalosis
    • Hypomagnesemia if hypokalemia is severe
    • Hypernatremia is rare
  • Patients may only present with hypertension and be normokalemic
• Laboratory testing
  • Screening - upright Aldosterone: renin activity ratio, or upright aldosterone:direct renin ratio
  • Confirmation
    • Fludrocortisone suppression test
    • Saline loading test
    • Saline infusion test
    • Captopril test
    • Losartan suppression test
• Imaging studies
  • Adrenal MRI or CT to screen for tumor