Enhancement of plasma corticotropin-releasing hormone in pregnancy-induced hypertension.

The role of a high CRH level in normal pregnancy remains unknown. Therefore we evaluated the concentrations of CRH and the related hormones in patients with pregnancy-induced hypertension. Fourteen women with pregnancy-induced hypertension, aged 20-39, at 30-39 gestational week, were investigated. The control group consisted of 20 healthy pregnant women matched according to gestational age. Plasma CRH beta-endorphin-like immunoreactivity, cortisol, and human placental lactogen were measured by radioimmunoassay, ACTH by an immunoradiometric method. It was found that in hypertensive patients the mean CRH concentration was significantly higher (4257 +/- 840 (SEM) ng/l) than that in healthy pregnant women (1083 +/- 227 ng/l, p less than 0.001). The concentration of ACTH, however, was only slightly higher 65.0 +/- 6.0 vs 50.7 +/- 2.5 ng/l p less than 0.025, whereas the differences in beta-endorphin, cortisol and human placental lactogen were not significant. In both groups there was no correlation between the CRH level and those of the related hormones. In healthy pregnant women the CRH level closely correlated with gestational age (r = 0.76, p less than 0.001), whereas in patients with hypertension no such correlation was present (r = 0.29). We assume that the marked enhancement of plasma CRH in pregnancy-induced hypertension is probably caused by its decreased breakdown in ischemic placental tissue, but its increased synthesis in the placenta and its indirect counterregulatory hypotensive role must also be considered.