Correct Answer

Blood tests will provide the best clue to this patient’s diagnosis of suspected primary hyperaldosteronism. Initial laboratory tests should include a basic metabolic profile, which may show hypokalemia with a normal renal function.

Another important screening test for diagnosing primary hyperaldosteronism is an early morning ratio of plasma aldosterone concentration (PAC) to plasma renin activity (PRA). If this ratio is high (at least 20) in the presence of a low PRA (1.0 ng/ml/hr), then this is suggestive of primary hyperaldosteronism.

Some centers include a 24-hour urinary aldosterone excretion test as a part of the initial evaluation of primary hyperaldosteronism, where a high urinary aldosterone excretion level (greater than 15 µg/24-hr) in the presence of high levels of urinary sodium excretion (greater than 200mEq/24-hr) is highly suggestive of primary hyperaldosteronism.