Plasma Renin Activity and Aldosterone Excretion Rate in Normal Subjects. II. Effect of Oral Contraceptive Agents

Abstract

Five normal subjects (total 15 subjects) were each given either Enovid-10, Orthonovum-10 or Provest. Plasma renin activity (PRA) and aldosterone excretion rate (AER) measurements were made during the first and third week of oral contraceptive pills (O.C.P.) and at the end of the week after discontinuing the O.C.P. Venous samples for PRA were obtained under 3 conditions: Condition 1, supine overnight and on unrestricted Na intake, Condition 2, supine overnight after 72 hr Na restriction (<10 mEq Na/24 hr), Condition 3, after Na restriction and standing 4 hr. Fifty-one per cent of the PRA and 23% of the AER values in the first week on the pills were greater than 2 sd above the normal mean. Thirty-three per cent of the PRA and 27% of the AER values during the third week of the pills were greater than 2 sd above the normal mean. The 8 subjects who had been taking O.C.P. for over 10 months prior to this study had a more pronounced effect than the 7 who had not previously taken O.C.P.