Plasma aldosterone-plasma renin activity ratio. A simple test to identify patients with primary aldosteronism

Thirty-two patients with hypertension and recurrent hypokalaemia were investigated on the suspicion of primary aldosteronism. On the basis of unsuppressible aldosterone secretion upon oral mineralocorticoid administration in 16 patients, a surgical exploration was made revealing a typical aldosteronoma in 12 of them, macronodular hyperplasia in two, micronodular hyperplasia in one, and micronodular hyperplasia together with a phaeochromocytoma in one patient. The remaining 16 patients with normal aldosterone suppressibility were considered to have primary hypertension. The discriminatory power of various biochemical tests related to the renin-angiotensin-aldosterone axis was analyzed in retrospect. The only parameter allowing a separation of patients with biochemically and surgically confirmed primary aldosteronism from the other group was the plasma aldosterone-plasma renin activity ratio. The present study therefore confirms the diagnostic value of this ratio for identifying patients with primary aldosteronism.