Primary aldosteronism due to unilateral adrenal microadenoma in an elderly patient: efficacy of selective adrenal venous sampling.

We encountered a case of drug-resistant hypertension and hypokalemia. Laboratory data suggested primary aldosteronism (PA). Computed tomography imaging appeared normal for a long duration with a left-sided nodule appearing far later; adrenal scintigraphy was first normal, and the second test showed right-sided uptake. However, a repeat selective adrenal venous sampling (SAVS) indicated a left-sided lateralization of the hypersecretion of aldosterone. Left adrenectomy was performed, and his clinical symptoms improved. The histopathological findings demonstrated the aldosterone-producing microadenoma with secondary micronodules. In conclusion, SAVS should be performed to determine the laterality of PA with obscure CT imaging.