Aldosteronism, Primary

KEY FEATURES

Essentials of Diagnosis

• Hypertension may be severe or drug-resistant

• Hypokalemia (in minority of patients) may cause polyuria, polydipsia, muscle weakness

• Low plasma renin; elevated plasma and urine aldosterone levels

General Considerations

• Refers to renin-independent, inappropriately high and non-suppressible aldosterone secretion

• Excessive aldosterone production

  • Increases sodium retention and suppresses plasma renin

  • Increases renal potassium excretion that can lead to hypokalemia

• Although most affected patients have hypertension, some may be normotensive

• Cardiovascular events are more prevalent in patients with aldosteronism (35%) than in those with essential hypertension (11%)

• May be caused by a unilateral aldosterone-producing adrenal cortical adenoma (Conn syndrome, 25%)

  • More common in women with a 2:1 ratio

  • Peaks between ages 30 and 50 years

• More commonly caused by adrenal cortical hyperplasia (75%)

  • More common in men with a 4:1 ratio

  • Peaks between ages 50 and 60 years

• Bilateral aldosteronism may be corticosteroid suppressible due to an autosomal-dominant genetic defect allowing adrenocorticotropic hormone stimulation of aldosterone production

• Malignant ovarian tumors are rare cause of hyperaldosteronism

Demographics

• The prevalence of primary aldosteronism is 5–10% in hypertensive patients and at least 20% in patients with resistant hypertension

• Should also be suspected with early-onset hypertension or stroke before age 50 years

• Patients of all ages may be affected, but the peak incidence is between 30 and 60 years

CLINICAL FINDINGS

Symptoms and Signs

• Hypertension is typically moderate but may be severe

• Some patients have only diastolic hypertension, without other symptoms and signs

• Edema (rare)

• Muscle weakness (at times with paralysis simulating periodic paralysis), paresthesias with tetany, headache, polyuria, and polydipsia may be seen in patients with hypokalemia

Differential Diagnosis

• Essential hypertension

• Primary aldosteronism and cases of low renin essential hypertension may overlap, making distinguishing between them difficult

• Hypokalemia due to other cause (eg, diuretics)

• Apparent mineralocorticoid excess syndrome caused by real licorice or anise-flavored drinks

• Hypertension and hypokalemia caused by medications (eg, abiraterone, posaconazole)

• Increased aldosterone secretion due to oral contraceptive use

• Renal vascular hypertension (hypertension and hypokalemia, but high plasma renin activity [PRA])

• Secondary hyperaldosteronism (dehydration, heart failure)

• Congenital adrenal hyperplasia: 11β-hydroxylase deficiency, 17α-hydroxylase deficiency

• Cushing syndrome

• Primary cortisol resistance

• Liddle syndrome

DIAGNOSIS

Laboratory Tests

• Plasma potassium should be determined in hypertensive individuals; however, hypokalemia is present in only 37% of affected patients: 50% of those with an aldosterone-producing adenoma and 17% of those with adrenal hyperplasia

• An elevated serum bicarbonate (HCO₃) concentration indicates metabolic alkalosis and is commonly present

• Testing for primary aldosteronism should be done for all hypertensive patients with any of the following:

  • Sustained hypertension above 150/100 mm Hg on 3 ...