The prediction of anatomical morphology of primary aldosteronism using serum 18-hydroxycorticosterone levels.

Serum 18-hydroxycorticosterone, aldosterone, and potassium were measured under basal conditions in 34 patients with documented primary aldosteronism, 10 patients with essential hypertension, and 9 normal subjects. The results revealed that 22 of 23 patients with aldosterone-producing adenomas had 18-hydroxycorticosterone levels greater than 100 ng/dl, and all 9 patients with idiopathic adrenal hyperplasia had plasma levels less than 100 ng/dl. Two patients with unusual macromicronodular hyperplasia of the adrenal glands had levels greater than 100 ng/dl. We found a significant relationship between serum potassium and the ratio of 18-hydroxycorticosterone to aldosterone in patients with idiopathic adrenal hyperplasia, but not in those with an aldosterone-producing adenoma. We conclude that measurement of serum 18-hydroxycorticosterone is a useful predictor of the etiology of primary aldosteronism.