PLASMA MEASUREMENTS OF CORTICOTROPIN-RELEASING HORMONE-BINDING PROTEIN IN NORMAL AND ABNORMAL HUMAN-PREGNANCY

Using corticotrophin-releasing hormone-binding protein (CRHBP) purifie d from human plasma and a 25 amino acid peptide corresponding to the C -terminus of CRHBP we have been able to produce rabbit polyclonal anti sera specific for CRHBP. This has allowed the development of a radioim munoassay which is able to detect CRHBP specifically in human plasma r egardless of the presence of endogenous CRH. We have used this assay t o estimate the level of CRHBP in non-pregnant human plasma to be appro ximately 20 nmol/l with a range of 9.1-40.6 nmol/l. We have also exami ned sequential plasma samples taken from 84 normal pregnant women at f ortnightly intervals from 16 weeks gestation through to term. Four wom en were also sampled during labour and the first week postpartum. The median plasma level of CRHBP at week 16 of normal pregnancy was 21.59 nmol/l, levels rose slightly during the early part of the third trimes ter (26.76 nmol/l at week 30, (P < 0.01) and fell markedly towards ter m (19.72 nmol/l, P < 0.01) with only 8.70 nmol/l at labour. CRHBP leve ls returned to normal non-pregnant levels within 48 h of parturition s uggesting a role for the fetoplacental unit in CRHBP production. In ei ght pregnancies complicated by diabetes, CRHBP levels at each gestatio nal age were similar to those recorded for normal pregnancy. However, in pregnancies complicated by pre-term labour (n = 9) and pre-eclampsi a (n = 7), plasma CRHBP levels were significantly reduced (P < 0.01).