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For further information, see CMDT Part 26-21: Primary Aldosteronism

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

  • Excessive aldosterone production

    • Increases sodium retention and suppresses plasma renin

    • Increases renal potassium excretion that can lead to hypokalemia

  • 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 ACTH stimulation of aldosterone production

  • Malignant ovarian tumors are rare cause of hyperaldosteronism

Demographics

  • Accounts for about 8% of cases of stage 2 (mild) hypertension and about 13% of cases of stage 3 (moderate) hypertension

  • Should also be suspected with early onset hypertension or stroke before age 50 years (or both)

  • Patients of all ages may be affected, but the peak incidence is between 30–60 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 frank tetany, headache, polyuria, and polydipsia may be seen in patients with hypokalemia

Differential Diagnosis

  • Essential hypertension

  • Hypokalemic thyrotoxic periodic paralysis

  • Renal vascular hypertension (hypertension and hypokalemia, but plasma renin activity is high)

  • Hypokalemia due to other cause, eg, diuretics

  • Secondary hyperaldosteronism (dehydration, heart failure)

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

  • Cushing syndrome

  • Excessive real licorice ingestion

  • Syndrome of cortisol resistance

Diagnosis

Laboratory Tests

  • Plasma potassium should be determined in hypertensive individuals; however, hypokalemia is present in only 37% of affected patients

  • 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 different days

    • Hypertension resistant to three conventional antihypertensive drugs, including a diuretic

    • Controlled blood pressure requiring four or more antihypertensive drugs

    • Hypokalemia, whether spontaneous or diuretic induced

    • Personal or family history of early onset hypertension or CVA at age ≤ 40 years

    • First-degree relative with primary aldosteronism

    • Presence of an adrenal mass

    • Low plasma renin activity

  • Testing protocol

    • For at least 2 weeks prior to testing, patients should

      • Have any hypokalemia corrected and then consume a ...

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