Levels of growth hormone and growth-hormone-releasing factor in cord blood.

In order to evaluate the mechanism of high growth hormone (GH) secretion in perinatal life, the levels of GH and growth-hormone-releasing factor (GRF) in cord blood were determined. Plasma-immunoreactive GRF was measured by a double antibody RIA method. The levels (mean +/- SD) of GH, GRF and somatostatin (SRIF) were 23.4 +/- 10.2 ng/ml, 49.5 +/- 11.7 and 41.5 +/- 10.4 pg/ml, respectively; they were remarkably higher than those of healthy adults. In statistical analysis, there were no significant relationships among the levels of GH, GRF or SRIF. We speculate that a high GRF release from the hypothalamus might increase the secretion of GH in the perinatal period.