Inactive Renin and Prostaglandin E2Production in Hyporeninemic Hypoaldosteronism*

Abstract

To ascertain whether inactive renin (IR) might predominate in the syndrome of hyporeninemic hypoaldosteronism (HH) and whether the production of prostaglandin E2 (PGE2), a potent stimulus for renin release, might be decreased, PRA [plasma renin activity], active renin (AR) and IR by the acid activation method and urinary PGE2 in 10 patients with HH were measured. In contrast to uniformly low levels of PRA (0.6 .+-. 0.2 ng/ml per h) and AR (2.7 .+-. 0.6), IR was either normal or elevated (14.7 .+-. 2.2 in HH; 11.8 .+-. 1.1 in 28 normal subjects) and the IR to AR ratio was markedly increased (8.5 .+-. 2.0 vs. 3.4 .+-. 0.5; P < 0.05). Urinary PGE2 was decreased in 4 patients but was in the normal range in 5 other patients with HH. In 16 human volunteers, PG inhibition with indomethacin led to a significant decrease in AR (P < 0.05) but not in IR, and the IR to AR ratio increased 2-fold (P < 0.02). HH is a disease apparently involving the defective conversion of IR to AR rather than impaired total renin production. In some patients, PG deficiency may contribute to the development of HH.