Hyperaldosteronism
Accounts of 0.5 - 10% of patients with HTN
Etiologies:
Aldosterone-producing adenoma (Conn's disease). Accounts for 60% of primary aldosteronism; three times more common in women.
Idiopathic hyperaldosteronism: 1/3 of cases of primary aldosteronism; normal-appearing adrenals or bilateral hyperplasia is seen on CT scan.
Glucocorticoid-suppressible aldosteronism: A rare autosomal-dominant form.
Angiotensin II-responsive adenoma: Accounts for 5% of primary aldosteronism
Aldosterone-producing adrenocortical carcinoma: Rare, <1% of primary aldosteronism. Hyperandrogensim is a clue to the diagnosis.
Clinical features:
HTN
Hypokalemia: although classic, is not necessary for diagnosis. So if Sr K+ is normal, don't dismiss hyperaldosteronism. Repeat Sr. K+. HA, muscle weakness (from hypokalemia)
Polyuria
Most patients are asymptomatic.
Plasma aldosterone concentration and plasma renin activity best evaluated after the patient is on high-salt diet or salt supplementation for one week.
Aldosterone level may also be evaluated with a 24-hour urine collection.
If primary aldosteronism is diagnosed, obtain an adrenal CT to distinguish Conn's and idiopathic hypoaldosteronism.
In primary hyperaldosteronism:
Hypernatremia, hypokalemia, metabolic alkalosis, increased aldosterone, decreased renin. CT/MRI of adrenals may show adenoma. If no adenoma found do adrenal vein sampling. If no localization of aldosterone, consider hyperplasia.
A PAC/PRA ratio >25 is characteristic.
Treatment:
Spironolactone in high doses, up to 400 mg/day or eplerenone blocks the mineralocorticoid receptor and usually normalizes K+. In men, the most common side effect is gynecomastia, but other side effects may occur - e.g., rash, impotence, and epigastric discomfort.
Unilateral adrenalectomy
▲PRA (plasma renin activity), ▲PAC (plasma aldosterone concentration):
2° hyperaldosteronism
Renovascular HTN
Diuretic use
Renin-secreting tumor
Malignant HTN
Coarctation of aorta
▼PRA, ▲PAC (>15 ng/dL) or (PAC/PRA ratio of >25): primary hyperaldosteronism
▼PRA, ▼PAC:
Congenital adrenal hyperplasia
DOC-producing tumor
Cushing's syndrome
Exogenous (mineralocorticoid)
Liddle's syndrome
11 beta-HSD deficiency