PROGRESSIVE NORMALIZATION OF GH BINDING PROTEIN AND IGF1 PLASMA LEVELS DURING THE FIRST YEAR OF GH THERAPY IN GH-DEFICIENT CHILDREN

Abstract

The short- and long-term effects of GH treatment on GH binding protein (GHBP) were examined in GH deficient children. Ten prepubertal children (6 boys, 4 girls), aged 2-10 yr, with isolated GH deficiency and short stature (SD from normal height = 2.4 ± 1.2) were studied before treatment and at regular intervals during GH therapy (0.50 IU/Kg/week). GHBP was measured by HPLC-gel filtration and correction was made forGH levels > 6 ng/ml. Results of plasma GHBP (% of radioactivity) and IGFI levels (ng/ml) are expressed as mean ± SEM. Normal values for age are: GHBP = 24.8 ±1.7%, IGFI = 105 ±10 ng/ml.The basal GHBP level is low. A significant decrease in GHBP is found 6 h after the first injection of GH. The time of induction of GHBP by GH appears variable: in half of the patients GHBP values arc normalized during the first 6 months of treatment. 100% of the GHBP values are normal after 12 monihs. Mean IGF1 levels are significantly increased 48 h following the first injection of GH and IGF1 levels arc normal after 6 months. No correlation was found between ihc plasma levels of GHBP and IGF1 nor between their increment under GH treatment. In conclusion, low GHBP levels arc found in GH-dcficicnt children. During GH therapy, the progressive increase in IGF1 levels occurs before the increase in GHBP levels.