The renin-aldosterone system in pre-eclampsia, essential and transient hypertension during pregnancy, and normotensive pregnant and non-pregnant control subjects.

Abstract

Abstract. Plasma renin concentration (PRC), plasma aldosterone concentration (PAC), and blood pressure were determined in the third trimester in pregnancy, 5 days and 6 months after delivery in pre-eclampsia, essential and transient hypertension in pregnancy and in normotensive pregnant and non-pregnant control subjects. PRC and PAC were elevated several fold above non-pregnant level in all groups during pregnancy. In pre-eclampsia PRC and PAC were 220 and 160%, respectively, above the levels 6 months after delivery, and thus lower than the corresponding values, 360 and 402%, in normotensive pregnancy. In essential and transient hypertension PRC and PAC increased to the same degree as during normotensive pregnancy. Urinary sodium excretion, serum sodium and creatinine clearance were reduced in pre-eclampsia, but not in essential and transient hypertension when compared to normotensive pregnant controls. All the parameters determined were the same as in non-pregnant controls 6 months after delivery in all groups. There were no correlations between blood pressure and PRC or PAC in any of the groups neither in pregnancy nor after delivery. It is concluded that the renin-aldosterone system is stimulated in lesser degree in pre-eclampsia than in both essential hypertension, transient hypertension and normotensive pregnancy, and there was no evidence for a causal relationship between the renin-aldosterone system and blood pressure neither in normotensive nor hypertensive pregnancy.