Growth hormone bioactivity in girls with Turner's syndrome: correlation with insulin-like growth factor I.
We have recently developed a new bioassay for growth hormone (GH) in serum, which is based on the ability of GH to suppress glucose use in cultured murine adipocytes. We tested the hypothesis that bioactive GH (B-GH) concentrations would correlate better with the GH-dependent peptides, IGF-I, and IGF-binding protein-3 (IGFBP-3) than would GH determined by conventional RIA (RIA-GH). Twenty-five girls with Turner's syndrome were studied. The subjects had ages ranging from 4.8 to 15.9 y and height SD from the mean (SD score) ranging from -0.77 to -5.67. Blood samples were obtained every 15 or 20 min for 12 h overnight. For each girl, an equal aliquot of each overnight sample was pooled for determination of B-GH, RIA-GH, IGF-I, IGFBP-3, LH, FSH, and estradiol. Measurable estradiol concentrations were present in six girls and were sufficient to suppress gonadotropin concentrations in two girls, but they did not alter B-GH, RIA-GH, IGF-I, and IGFBP-3 concentrations compared with the age-matched girls without measurable estradiol concentrations. Hence, data for all girls were combined for subsequent regression analyses. RIA-GH did not correlate significantly with B-GH, IGF-I, or IGFBP-3. B-GH exhibited a significant correlation with IGF-I (r = 0.407, p < 0.05), and the correlation with IGFBP-3 was better than that for RIA-GH (r = 0.355 versus 0.064, B-GH and RIA-GH, respectively). None of the B-GH, RIA-GH, IGF-I, or IGFBP-3 concentrations had a significant correlation with height SD score or height velocity SD score.(ABSTRACT TRUNCATED AT 250 WORDS)
Foster
C M
CM
Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor 48109.
Borondy
M
M
Markovs
M E
ME
Hopwood
N J
NJ
Kletter
G B
GB
Beitins
I Z
IZ
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000293:Adolescent; D000818:Animals; D001681:Biological Assay / Q000379:methods; D001827:Body Height; D002352:Carrier Proteins / Q000097:blood; D002648:Child; D002675:Child, Preschool; D005069:Evaluation Studies as Topic; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005947:Glucose / Q000378:metabolism; D013006:Growth Hormone / Q000032:analysis / Q000097:blood* / Q000494:pharmacology; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D051379:Mice; D011863:Radioimmunoassay; D014424:Turner Syndrome / Q000097:blood* / Q000473:pathology
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone; D005947:Glucose