A case report of aldosterone producing adenoma with masked hyperaldosteronemia.

A 50-year old female with primary aldosteronism and masked hyperaldosteronemia is reported. Her blood pressure was 176/110 mmHg with no paralysis of hypokalemia. Serum potassium, aldosterone and renin activity were 4.3 mEq/L, 17 ng/dl and 0.6ng/ml/h, respectively. Following a stimulation test by sodium loading and furosemide plus standing, neither aldosterone nor renin activity responded. Adrenal computed tomographic scanning, ultrasonography and cortical scintiscanning failed to reveal the tumor mass. A definite diagnosis of aldosterone producing adenoma was made after adrenal venous sampling in which the concentration of aldosterone was 15-fold greater in the right adrenal vein than in the left. The diagnosis of right adrenal cortical adenoma was confirmed by surgery. Thus, this case indicates the usefulness of the sampling technique in making an accurate diagnosis for primary aldosteronism with normo-kalemia, normo-aldosteronemia and normo-reninemia.