Plasma Renin Activity and Aldosterone Excretion Rate in Normal Subjects. I. Effect of Ethinyl Estradiol and Medroxyprogesterone Acetate

Abstract

Ethinyl estradiol (E.E.) was given 0.5 rag daily for 3 weeks to 13 normal subjects. Plasma renin activity (PRA) was measured before and during the first and third week of E.E. with the subjects under 3 combinations of sodium intake and body posture. Aldosterone excretion rate (AER) was measured in association with the PRA under normal and low Na intake. There was a slight but statistically insignificant increase in PRA during the first week of E.E. administration. However, there was a significant (p 0.02 or lower) increase in PRA values under all 3 combinations of sodium intake and posture and a significant increase in AER under both normal and low Na intake during the third week of E.E. administration. E.E. manufactured 6–7 yr before use caused a greater effect on PRA values than did E.E. manufactured within a year before use. Medroxyprogesterone acetate (M.P.A.) in doses of 20 mg daily for 3 weeks caused no apparent change in PRA. It did cause a significant decrease in urinary AER in the third week on unrestricted sodium intake, but the response to sodium restriction was unchanged by M.P.A.