Case Summary

• This patient is a young, White woman of average build, with a five-year history of uncontrolled hypertension. Her young age, resistant type of hypertension, and history of hypokalemia suggest secondary hypertension due to aldosterone excess. In the absence of an abdominal bruit or renal insufficiency, primary hyperaldosteronism is more likely than renal vascular disease to be the correct diagnosis.
• An elevated ratio of plasma aldosterone concentration to plasma renin activity of 40, a low plasma renin activity (less than 1.0 ng/ml/hr), a serum potassium level of 3.2 mg/dl, a 24-hour urinary aldosterone excretion of 42 µg/24-hr, and a 24-hr urinary sodium excretion of 200 mEq/24-hr, when considered together, are highly suggestive of primary aldosteronism. This was confirmed by an NaCl suppression test, which showed a failure to suppress urinary aldosterone excretion to less than 12 µg/24-hr. A high-resolution adrenal computerized tomography scan showed a left-sided, 1.4 cm adrenal mass suggestive of an adenoma.
• This patient has primary hyperaldosteronism, which is contributing to her resistant form of hypertension. The goal of therapy in this patient with uncomplicated hypertension is to maintain her BP at less than 140/90 mmHg.
• An aldosterone receptor antagonist should be effective in controlling BP in patients with primary hyperaldosteronism. The selective aldosterone receptor blocker eplerenone would be the drug of choice as it would avoid the side effects of its older, non-selective counterpart, spironolactone. As this drug was not yet available in the US, the patient was started on spironolactone. She showed a dramatic BP response at the 50 mg dose, improving to 118/70 mmHg in 10 weeks. The patient was able to discontinue the diltiazem, atenolol, and potassium supplements.
• The functional status of the unilateral adrenal mass was determined by adrenal vein sampling for aldosterone and cortisol. Aldosterone secretion lateralized to the left side, which correlated with the side of the adrenal mass noted on high-resolution computerized tomography.
• The patient then underwent left adrenalectomy. Her BP has since remained normotensive on no antihypertensive agent. Her biochemical values normalized. The histopathology of the adrenal specimen showed it to be an adrenal adenoma.