Blood pressure and vasoactive hormones in mild preeclampsia and normal pregnancy

Changes in vasoactive hormones are reported to play an important role in the pathogenesis of preeclampsia linking placental hypoperfusion with hypertension, systemic disease, and proteinuria. We, therefore, studied diurnal patterns of vasoactive hormones in mild preeclampsia.

Venous blood samples were drawn every 2 h over 25 h for measurements of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), norepinephrine, renin activity, and aldosterone and two urine collections (12 h each) for stable prostaglandin metabolite measurements. The patients were nine women with mild preeclampsia and, for comparison, nine control women matched for gestation and parity.

Women with mild preeclampsia had higher norepinephrine levels throughout 25 h, and lower systemic prostacyclin production as measured by the urinary 2,3-dinor-6-keto PGF1 alpha excretion during the daytime. Plasma endothelin and ANP and BNP concentrations tended to be higher throughout 25 h in preeclampsia, but differences between the two groups did not reach levels of statistical significance. Plasma renin activity and aldosterone did not differ between the groups. Whereas control women exhibited a diurnal variation in plasma norepinephrine, ANP, BNP, and aldosterone, and in both urinary prostacyclin and thromboxane A2 metabolites, this was less distinct or absent in patients with mild preeclampsia.

We conclude that mild preeclampsia is associated with elevated plasma norepinephrine levels, lower systemic daytime production of prostacyclin, and blunting of the normal diurnal variation for a number of indices including plasma levels of BNP, ANP, norepinephrine, and aldosterone, and urinary prostacyclin metabolites.