An Indolent Aldosterone-Producing Adenoma in a Young Hypertensive Patient Manifested during 7-Year Follow-up.

Early identification and treatment optimization for the patients with primary aldosteronism are crucial to minimizing the enhanced cardiovascular risks. However, the natural course of primary aldosteronism development remains unclear. An 18-year-old man visited our outpatient clinic for hypertension. At baseline, confirmatory testing ruled out primary aldosteronism, and computed tomography showed normal adrenal glands. During subsequent outpatient follow-up, his blood pressure gradually increased despite treatment with multiple antihypertensive medications. At his 7th-year visit, he eventually presented severe hypokalemia with a right adrenal tumor. Endocrinological evaluation revealed hyperaldosteronism along with suppressed renin activity, suggesting primary aldosteronism. Subsequent diagnostic procedures, including the captopril challenge test and adrenal venous sampling, confirmed the diagnosis of primary aldosteronism due to the right adrenal tumor. The patient underwent right adrenalectomy, leading to remission of primary aldosteronism. Histopathological analysis confirmed the resected adrenal tumor as a KCNJ5-mutated aldosterone-producing adenoma. Notably, plasma steroid profiling retrospectively revealed elevated peripheral 18-oxocortisol levels, a biomarker of KCNJ5-mutated aldosterone-producing adenomas, before the diagnosis of primary aldosteronism. This case clearly demonstrated a natural course of unilateral primary aldosteronism and highlights the potential utility of steroid profiling as part of the diagnostic strategy for primary aldosteronism.