Changes in the renin-angiotensin-aldosterone and kallikrein-kinin systems during normal and hypertensive pregnancy.

We conducted a prospective and serial study of blood pressure (BP) and of the changes in the renin-angiotension-aldosterone system (RAAS) and of one factor in the kallikrein-kinin system during normal pregnancy and in patients with pre-existing or developing hypertension in pregnancy. Strict diagnostic criteria were used to define pre-eclampsia (PE), essential hypertensives (EH) and other hypertension (OH) in pregnancy. In normotensive pregnant women (n = 26) there was a rise in all components of the RAAS measured: plasma renin activity (PRA), plasma aldosterone concentration (PAC) and urinary aldosterone excretion (tU-Aldo), from week 12 to week 20 of pregnancy, compared with non-pregnant control subjects (n = 24) of similar age. Peak values were observed at week 30, whereafter fairly constant levels were maintained. Plasma and urinary aldosterone levels were increased 6-10 fold. Urinary kallikrein excretion (tU- Kall ) was increased at weeks 12-20, but at weeks 30-36 roughly the same mean values were observed as for non-pregnant control subjects. On the other hand, different results were obtained in the hypertensive patients, especially those with PE (n = 18). PRA was depressed in the PE group to values about those observed in non-pregnant control subjects. PRA was also significantly lower in the PE group than in EH (n = 8) or OH (n = 16) groups. PAC and tU-Aldo were also much lower in PE patients than in normal pregnant women at comparable gestational ages, but not significantly different from EH patients, whereas those with OH had both PAC and tU-Aldo values comparable to normal pregnant women.(ABSTRACT TRUNCATED AT 250 WORDS)