Concurrent hypercortisolism and hyperaldosteronism due to an adrenal adenoma.

The case of a 39-year-old woman with Cushing's syndrome, hypertension and severe hypokalemia, caused by a unilateral adrenal adenoma composed of cells of the zona fasciculata histological type, is described. Plasma renin activity, plasma levels of mineralocorticoids and the aldosterone secretion rate were determined before and after surgical removal of the adenoma. The tumor appeared to produce autonomously cortisol as well as corticosterone, 18-hydroxycorticosterone and aldosterone. This condition has not previously been described in the literature and might be explained by strong expression of the full spectrum of activities of the mitochondrial enzyme P450 C11 by the tumor cells. Interestingly, despite hyperaldosteronism, plasma renin activity was not suppressed.