Hyperaldosteronism, Primary

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Hypertension due to sodium and water retention

• Hypokalemia and metabolic alkalosis

• Suppressed renin and angiotensin synthesis

• Elevated plasma aldosterone levels

• Imaging results showing adrenal adenoma or bilateral hyperplasia

GENERAL CONSIDERATIONS

• Increased autonomous production of aldosterone by the adrenal gland

• This causes sodium retention, plasma volume expansion, and hypertension

• Renal loss of potassium and bicarbonate causes hypokalemia and alkalosis

  • – Patients usually identified because of hypertension and sometimes hypokalemia

  • – Familial hyperaldosteronism is the cause in 5–10% of cases

  • – Somatic mutations account for about 50% of cases and involve the genes encoding potassium channels, voltage-dependent C-type calcium channels, and sodium/potassium and calcium ATPases

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Usually asymptomatic

PHYSICAL EXAM FINDINGS

• Hypertension, rarely severe

DIFFERENTIAL DIAGNOSIS

• Other causes of hypertension (primary aldosteronism accounts for 10–20% of hypertensive patients referred to hypertension clinics)

• Other causes of hypokalemia

DIAGNOSTIC EVALUATION

LABORATORY TESTS

• Serum potassium reduced in about 40%

  • – Reduced plasma renin activity

  • – Elevated plasma aldosterone

  • – Aldosterone to plasma renin ratio (the definition of abnormal varies with the laboratory)

ELECTROCARDIOGRAPHY

• Occasionally left ventricular hypertrophy or left atrial abnormality is seen

IMAGING STUDIES

• CT scan distinguishes adrenal hyperplasia from adenoma

DIAGNOSTIC PROCEDURES

• Aldosterone suppression test

• Adrenal vein aldosterone levels in selected cases

TREATMENT

CARDIOLOGY REFERRAL

• Suspected cardiac disease

HOSPITALIZATION CRITERIA

• Planned surgery

MEDICATIONS

• Aldosterone antagonists for adrenal hyperplasia: spironolactone 100–200 mg/day PO or eplerenone 25–100 mg/day

• Calcium channel blockers

• Amiloride 10–40 mg/day

THERAPEUTIC PROCEDURES

• CT-guided radiofrequency ablation is a potential alternative to surgery for adenomas

SURGERY

• Surgical resection of adenoma

DIET AND ACTIVITY

• Low-sodium diet

ONGOING MANAGEMENT

HOSPITAL DISCHARGE CRITERIA

• Successful surgery

FOLLOW-UP

• Depends on situation

COMPLICATIONS

• Those of systemic hypertension

PROGNOSIS

• Excellent with early recognition and management

PREVENTION

• Serum potassium off diuretics should be part of every hypertension evaluation

• In difficult to manage patients, a plasma aldosterone/renin activity ratio should be measured

RESOURCES