The diagnosis of primary hyperaldosteronism.

An aldosterone-suppression test based on a simple method of extracellular-fluid volume expansion over three days reliably discriminated between patients with aldosterone-producing adenomas, idiopathic adrenal hyperplasia, and essential benign hypertension. In patients with primary hyperaldosteronism adrenal-vein plasma aldosterone/cortisol concentration ratios successfully lateralised all 21 adenomas. In patients with an adenoma the contralateral adrenal gland was always suppressed, as indicated by a ratio which was less than that seen in the lower inferior vena cava, whereas in patients with hyperplasia the adrenal-vein aldosterone/cortisol concentration ratio from each adrenal was always greater than that seen in the lower inferior vena cava. Thus adrenal-vein sampling not only lateralises solitary adenomas but also discriminates between patients with an adenoma or hyperplasia. However, in view of the diagnostic reliability of the suppression test, it is suggested that adrenal-vein sampling is unnecessary in hyperaldosteronism due to adrenal hyperplasia.