Serum Growth Hormone Binding Protein Activity in Healthy Neonates, Children and Young Adults: Correlation With Age, Height and Weight

Abstract

Serum growth hormone binding protein (GHBP) activity was estimated in healthy neonates (n = 6), children and adolescents (n = 97) and young adults (n = 19). GHBP activity was measured by incubating 125I-hGH (human growth hormone) (approximately 25,000 c.p.m.) with serum (100 microliters) in the presence and in the absence of excess unlabelled hGH, followed by separation of specifically bound 125I-hGHBP complexes from free 125I-hGH by gel filtration on Ultrogel AcA44 minicolumns. The results are expressed as the percentage specific binding relative to an adult reference serum (%RSB), after correction for endogenous hGH of the unknown serum. The between-assay coefficients of variation for two sera of %RSB activity of 51.2 and 115.4% were 6.0 and 7.0% respectively. In neonates, low values of serum GHBP were found (%RSB = 27.1 +/- 5.0 SEM) followed by a major rise during the first 6 years of life to a mean value (%RSB = 68.3 +/- 4.1 SEM) which more than doubled that of neonates. Thereafter, values rose progressively throughout childhood and puberty to reach maximum values in young adults (%RSB = 95.0 +/- 3.1 SEM). A novel observation was that serum GHBP activity correlated significantly with height standard deviation score (SDS) (males: r = 0.77, P less than 0.001; females: r = 0.56, P = 0.01) and weight SDS (P less than 0.001) for both sexes before puberty. During puberty GHBP correlated only with weight SDS in males (r = 0.60, P less than 0.01). In all age groups studied, no correlation could be found between serum GHBP and height velocity.

Progressive Normalization of Growth Hormone-Binding Protein and IGF-I Levels in Treated Growth Hormone-Deficient Children

“…A positive correlation between serum GHBP pretreatment levels and BMI was found in this study as in others (19)(20)(21)(22), suggesting that nutritional factors affect BMI and GHBP in parallel. As expected, IGF-I levels increased significantly during the first 3 mo of hGH treatment, and they remained constant thereafter.…”

Effect of insulin-like growth factor-I treatment on serum androgens and testicular and penile size in males with Laron syndrome (primary growth hormone resistance)

“…In the prepubertal period, the response of endogenous GH to pharmacological stimuli often becomes evident only after priming with sex hormones (10)(11)(12). During puberty the secretion of both GH and IGF-I increases (13,14). Kamp et al (15) in a recent review of available data concluded that GH treatment of prepubertal short children results in a somewhat faster rate of progression in boys and an earlier onset of puberty in girls.…”

Serum Growth Hormone-Binding Proteins in the Human Fetus and Infant

“…In the human fetus, in spite of very high levels of circulating GH (13,14), only low levels of tissue GH receptors (15,16) and of serum GH-BP (17)(18)(19) have been reported. The physiologic significance of these findings remains unclear.…”