Unilateral adrenal hyperplasia causing primary aldosteronism: limitations of I-131 norcholesterol scanning

Primary aldosteronism is a disorder that is commonly considered in patients referred to the hypertension clinic. The ease of measuring the random aldosterone-to-renin ratio in conjunction with an elevated serum aldosterone level has led to an increased screening for this disorder. Typically, patients undergo a confirmatory test after a positive screening test. However, once primary aldosteronism is confirmed, subtype delineation is critical to decide on the optimal treatment. We report a patient with resistant hypertension and primary aldosteronism with a normal computed tomographic scan of the adrenal glands, a left-sided uptake on adrenal scintigraphy, and a right-sided lateralization of aldosterone after adrenal vein sampling. A repeat adrenal vein sampling confirmed the aldosterone lateralization to the right adrenal gland, which was then removed laparoscopically. The patient had a good clinical and biochemical response, and unilateral adrenal hyperplasia was discovered at histology. Excessive reliance on adrenal scintigraphy without adrenal vein sampling may lead to serious errors in patient management.