Influence of high renin substrate levels on renin-angiotensin system in pregnancy

Abstract

A marked elevation of renin substrate was found in plasma of 22 women in normal pregnancy as well as in 8 patients with toxemia. This elevation is most likely due to the increased secretion of estrogens reported in pregnancy. Seven nonPregnant women treated with estrogens or contraceptive preparations containing estrogens and progestational agents had renin substrate levels in the range found in pregnancy. Since the amount of angiotensin farmed during incubation of plasma per unit of renin increased progressively with the elevation of renin substrate, the renin-angiotensin system would be more efficient in retaining sodium in pregnant than in nonpregnant women. In the later stages of gestation many of the renin levels were in the normal nonpregnant range. The lowest renin levels were found in toxemia where a strong positive sodium balance occurs. Renin levels in peripheral plasma furnish an indirect means of assessing the state of sodium balance in pregnancy.