Abstract Body: Background: Mechanisms underlying the development of pre-eclampsia in humans are not well-understood. Activation of the RAAS with markedly increased secretion of aldosterone is a key feature of normotensive pregnancy, and thought to be impaired in pre-eclampsia. The purpose of our study was to perform RAAS profiling in pre-eclampsia, where we hypothesized reduced concentrations of aldosterone in serum of patients with pre-eclampsia compared to pregnant patients without pre-eclampsia.
Methods: This is a case-control study of 50 patients with pre-eclampsia and 50 gestational age-matched controls. Clinical characteristics (blood pressure, biochemical laboratory values) and blood samples were collected upon enrollment, and maternal and fetal outcomes were collected at delivery. Blood samples were analyzed for angiotensin I, angiotensin II, and aldosterone by LC-MS/MS using RAAS-Triple A. All patients have been recruited, and preliminary data are available for the cases.
Results: The mean gestational age of pre-eclampsia cases was 27.9 + 6.2 weeks. RAAS profiling revealed two distinct subpopulations, where 35 patients had concentrations of aldosterone in serum that were characteristically low for pre-eclampsia: below 204 pmol/L, with median and interquartile range (IQR) of 120.0 and 35.0 – 132.2 pmol/L, and an aldosterone to angiotensin II ratio (AA2-R) of 1.05 (compared to previously published results where the median and IQR of aldosterone in pregnant women at 28 weeks was 724.8 and 376.6 – 1197 pmol/L, and median AA2-R of 4.15). In contrast, 15 patients had aldosterone concentrations more characteristic of normal pregnancy, with a median and IQR of 589.8 and 402.2– 769.6 pmol/L, and median AA2-R of 4.8). For comparison, a recent population study of non-pregnant adults determined median and IQR of aldosterone concentrations of 93 and 57.9 – 153.9 pmol/L using RAAS Triple-A.
Conclusions: These data suggest two distinct phenotypes of pre-eclampsia based on RAAS profiling. Consistent with previous literature, our data indicate that pre-eclampsia is predominately characterized by reduced secretion of aldosterone, where concentrations are comparable to non-pregnant individuals. In contrast, we report that approximately one-third of patients with pre-eclampsia have elevated concentrations of aldosterone expected for pregnancy, suggesting multiple mechanisms for pre-eclampsia in humans defined by the presence or absence of elevated aldosterone secretion.