[Five cases of primary aldosteronism: a comparative study on diagnosis for localization of adrenal tumor]

Five cases of primary aldosteronism are reported, and several techniques to localize the tumor were evaluated. On computed tomography which is a noninvasive technique, low density areas were identified in all cases, and definite adenomas were clearly detected in three of five cases. Adrenal scintigraphy with 131I-19-iodocholesterol is another noninvasive technique that showed unilaterally increased uptake in two cases. Dexamethasone inhibits the uptake of labeled cholesterol by hyperplastic or normal glands but does not interfere with the uptake by an adenoma. Using this technique, it was possible to lateralize additionally the tumor in one case. Adrenal venography which is an invasive technique that showed a circular deformity with tumor depicted the tumor in only one case. However, the venous effluent was sampled simultaneously from both glands and the plasma aldosterone concentration in each sample assayed. An increase in aldosterone concentration on only one side localizes the aldosterone producing adenoma to that side. The method was highly accurate, and provided the correct diagnosis preoperatively in all cases. Being a noninvasive technique, computed tomography and adrenal scintigraphy should be undertaken initially, and venography coupled with measurements of aldosterone concentrations in the left and right adrenal venous effluent could be a definitive procedure before surgery.