title: Free and total insulin-like growth factors and insulin-like growth factor binding proteins during 14 days of growth hormone administration in healthy adults.
abstract: The objective was to investigate the effect of growth hormone (GH) administration on circulating levels of free insulin-like growth factors (IGFs) in healthy adults. Eight healthy male subjects were given placebo and two doses of GH (3 and 6 IU/m2 per day) for 14 days in a double-blind crossover study. Fasting blood samples were obtained every second day. Free IGF-I and IGF-II were determined by ultrafiltration of serum. Total IGF-I and IGF-II were measured after acid-ethanol extraction. In addition, GH, insulin, IGF binding protein 1 (IGFBP-1) and IGFBP-3 were measured. Serum-free and total IGF-I increased in a dose-dependent manner during the 14 days of GH administration. After 14 days, serum-free IGF-I values were 610 +/- 100 ng/l (mean +/- SEM) (placebo), 2760 +/- 190 ng/l (3 IU/ m2) and 3720 +/- 240 ng/l (6 IU/m2) (p = 0.0001 for 3 and 6 IU/m2 vs placebo; p = 0.004 for 3 IU/m2 vs 6 IU/m2). Total IGF-I values were 190 +/- 10 micrograms/l (placebo), 525 +/- 10 (3 IU/m2), and 655 +/- 40 micrograms/l (6 IU/m2) (p < 0.0001 for 3 and 6 IU/m2 vs placebo; p = 0.04 for 3 IU/m2). There were no differences in the levels of free or total IGF-II during the three study periods. Insulin-like growth factor binding protein 1 was decreased during GH administration (p = 0.04 for placebo vs 3 IU/m2; p = 0.006 for placebo vs 6 IU/m2). In conclusion, fasting serum free IGF-I increased dose dependently during GH administration and free IGF-I increased relatively more than total IGF-I. This may partly be due to the decrease in IGFBP-1.
authors.affiliation: Institute of Experimental Clinical Research, Aarhus University Hospital, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Skjaerbaek
authors.forename: J
authors.initials: J
authors.lastname: Frystyk
authors.forename: J
authors.initials: J
authors.lastname: Møller
authors.forename: J S
authors.initials: JS
authors.lastname: Christiansen
authors.forename: H
authors.initials: H
authors.lastname: Orskov
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D019382:Human Growth Hormone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006801:Humans; D007279:Injections, Subcutaneous; D007328:Insulin / Q000097:blood / Q000378:metabolism; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood* / Q000187:drug effects / Q000378:metabolism; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood* / Q000187:drug effects / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D008297:Male
chemical_list: D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II