Growth hormone-binding proteins during human pregnancy: maternal, fetal and neonatal data

Serum levels of growth hormone-binding protein (GHBP) were measured by high-performance liquid chromatography (HPLC) gel filtration in serum of 30 pregnant women and in cord serum of 69 preterm and term infants. In pregnant women, the mean +/- SD serum level of GHBP was 32.4% +/- 5.6%. Polynomial regression analysis showed a significant (P = 0.01) second-order relationship between the duration of pregnancy and serum GHBP levels, with increasing levels during the first half of pregnancy and decreasing levels thereafter. In cord serum, the mean +/- SD serum level of GHBP was 3.1% +/- 1.4% (n = 51) in preterm and 4.2% +/- 1.3% (n = 18) in term neonates. Serum GHBP concentrations were related to gestational age (r = 0.35; P < 0.005) and to intrauterine nutritional state as evaluated by the ponderal index (r = 0.30; P < 0.02). In four term neonates, serum levels of GHBP were measured before and after an exchange transfusion (ET). Before the ET the serum GHBP level was 6.7% +/- 2.4% and at the end it was 25.3% +/- 2.6%. Thereafter, serum GHBP levels decreased slowly. Analysis of the elimination curve by exponential stripping showed a biexponential elimination pattern: GHBP (%) = 40.e(-5.1E-03 x time) + 64.e(-2.5E-04 x time). The serum half-life of the GHBP complex was estimated to be about 2 days.