Kinetics of insulin-like growth factor (IGF) and IGF-binding protein responses to a single dose of growth hormone

The in vivo physiological relationships among GH, the insulin-like growth factors (IGFs), and the IGF-binding proteins (IGFBPs) are not completely defined, and single random measurements of these serum proteins do not completely reveal their dynamic relationships. We report the kinetic responses of...

Full description

Saved in:
Bibliographic Details
Published in:The journal of clinical endocrinology and metabolism 1997-07, Vol.82 (7), p.2266-2274
Main Authors: LEE, P. D. K, DURHAM, S. K, MARTINEZ, V, VASCONEZ, O, POWELL, D. R, GUEVARA-AGUIRRE, J
Format: Article
Language:English
Subjects:
Adolescent
Adult
Biological and medical sciences
Child
Child, Preschool
Female
Functional investigation of endocrine glands and genital system
Growth Hormone - blood
Growth Hormone - deficiency
Growth Hormone - pharmacology
Humans
Infant
Insulin-Like Growth Factor Binding Proteins - blood
Investigative techniques, diagnostic techniques (general aspects)
Male
Medical sciences
Receptors, Somatotropin - deficiency
Recombinant Proteins - pharmacology
Somatomedins - metabolism
Time Factors
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The in vivo physiological relationships among GH, the insulin-like growth factors (IGFs), and the IGF-binding proteins (IGFBPs) are not completely defined, and single random measurements of these serum proteins do not completely reveal their dynamic relationships. We report the kinetic responses of the IGFs and IGF-binding proteins to exogenous GH in 23 subjects with untreated GH deficiency [5 women and 18 men; age, 15.0 +/- 6.2 yr (+/- s.d.), height z-score = -4.4 +/- 2.2 (+/- s.d.); body mass index = 19.3 +/- 2.4 kg/m2]. After an overnight fast, subjects were given a sc dose of recombinant human GH (2.85 i.u./m2), and blood was sampled from an indwelling peripheral venous catheter 0, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, and 24 h after the injection. Subjects were then treated with recombinant human GH (2.85 i.u./m2.day); fasting samples were obtained at 3 months (n = 22), and timed sampling was repeated at 6 months (n = 21). Fasting levels of IGF-I, free IGF-I, IGF-II, IGFBP-3, and insulin increased significantly within 3 months of GH treatment, whereas IGFBP-1, IGFBP-2, and IGFBP-6 showed no change. In the timed sampling studies at 0 and 6 months, GH levels peaked 3 h after treatment; the degree of rise and the rate of decline were both greater at 6 months. IGF-I levels increased beginning at 4 h, continuing throughout the 24-h period at month 0, whereas a plateau was observed after 6-8 h during the 6-month study. Free IGF-I paralleled total IGF-I except during fasting, when it varied inversely with IGFBP-1. IGFBP-3 and IGF-II both showed late (> 20 h) responses to a dose of GH, whereas IGFBP-2 and IGFBP-6 showed minimal changes. IGFBP-1 varied inversely with insulin, which, in turn, varied with meal intake. Comparative studies in 2 subjects with GH receptor deficiency showed no response to exogenous GH. However, both IGFBP-1 and IGFBP-2 were several-fold elevated, and IGFBP-1 varied inversely with the low insulin levels. Our data are the first to examine multiple elements of the serum IGF system in response to GH in both GH-deficient and replete states. The relationships of the different response patterns provide insight into the physiology of this system and may guide future studies.
ISSN:0021-972X
1945-7197
DOI:10.1210/jc.82.7.2266