Image of the Month—Quiz Case

A 56-year-old woman was referred with a history of poorly controlled hypertension of 5 years associated with hypokalemia, with potassium levels ranging from 2.1 to 3.0 mEq/L (the conversion from milliequivalents per liter to millimoles per liter is 1:1). Despite treatment with 2 mg of prazosin hydrochloride twice daily and 100 mg of atenolol every morning, her blood pressure remained elevated at 150/100 mm Hg. Her potassium levels could only be maintained at 3.5 mEq/L with 1200 mg of potassium replacement per day. Biochemical testing demonstrated a suppressed plasma renin activity of 150 pg/mL per hour (reference range, 660-3080 pg/mL per hour; to convert picograms per milliliter to picomoles per liter, multiply by 0.0237) and an elevated plasma aldosterone concentration of 33.2 ng/dL (reference range, 0.6-21.9 ng/dL; to convert nanograms per deciliter to picomoles per liter, multiply by 27.74). The elevated aldosterone to renin ratio of 221 supported a diagnosis of primary hyperaldosteronism (PH). A postural study after salt loading for 3 days was subsequently performed. This was inconclusive as the rise in the plasma aldosterone concentration was less than 30%. The biochemical results at 8 AMin the supine position were as follows: plasma aldosterone concentration, 30.0 ng/dL; plasma renin activity, 150 pg/mL per hour; and cortisol concentration, 11.5 μg/dL (to convert micrograms per deciliter to nanomoles per liter, multiply by 27.588). At 12 PMin the erect position, the results were as follows: plasma aldosterone concentration, 35.8 ng/dL; plasma renin activity, 70 pg/mL per hour; and cortisol concentration, 16.9 μg/dL. Computed tomography of the adrenal glands was performed (Figure) and the patient underwent adrenal venous sampling with corticotropin infusion, which demonstrated lateralization of aldosterone secretion to the left. The left-to-right cortisol-corrected aldosterone ratio was 13.5:1.

Figure. 

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Computed tomographic scan demonstrating a 9 × 8-mm well-defined nodule in the left adrenal gland suggestive of adrenal adenoma. This finding was atypical for adrenal hyperplasia, which usually appears as a diffuse enlargement of the gland.

A. PH secondary to adrenal adenoma

B. PH secondary to bilateral adrenal hyperplasia

C. PH secondary to unilateral adrenal hyperplasia

D. PH secondary to adrenal carcinoma