Evaluation of diagnostic tests in the differential diagnosis of primary aldosteronism: unilateral adenoma versus bilateral micronodular hyperplasia.

Effective management of primary aldosteronism is dependent upon correct localization of excessive aldosterone production. We report our results of localization studies in patients with biochemically and pathologically confirmed primary aldosteronism. Retrospective chart review identified 69 patients with unilateral adrenal adenoma and 11 with adrenal hyperplasia. Correct unilateral versus bilateral localization of excessive aldosterone production was predicted in 70% versus 71%, respectively, by adrenal venography, 100% versus 63% by adrenal vein hormone sampling, 46% versus 56% by adrenal nuclear scanning and 69% versus 13% by anomalous postural decline of aldosterone. Adrenal computerized tomography appeared to localize correctly 86% versus 80% of the lesions. Unilateral adrenalectomy normalized blood pressure in 79% of the patients with unilateral adenomas versus only 18% of those with adrenal hyperplasia. Once primary aldosteronism is confirmed, localization by adrenal vein sampling, adrenal venography and adrenal computerized tomography is most effective in directing antihypertensive therapy.