Enhanced sensitivity growth hormone (GH) chemiluminescence assay reveals lower postglucose nadir GH concentrations in men than women

I. M. Chapman, M. L. Hartman, M. Straume, M. L. Johnson, J. D. Veldhuis, M. O. Thorner

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166 Scopus citations

Abstract

Modifications were made to a commercially available human (h) GH chemiluminescence assay (Nichols Luma Tag hGH assay), which improved its sensitivity to 0.002 μg/L. The results of this assay had a high correlation with those of the Nichols hGH immunoradiometric assay (IRMA; r = 0.91; P < 0.001). The addition of recombinant hGH-binding protein (0.1-10 nmol/L) to standards and serum samples caused a dose-responsive reduction in measured GH in both the chemiluminescence assay and the IRMA; at physiological concentrations of hGH-binding protein, a 10-20% reduction was observed. Fifteen normal young adults (nine men and six women) underwent a standard 100-g oral glucose tolerance test, and plasma GH was measured from 30 min before until 5 h after glucose ingestion. GH was measurable in all samples with the chemiluminescence assay, but fell below the sensitivity of the IRMA in 59% of the samples. There was no difference between baseline or peak glucose levels in male and female subjects, but serum GH concentrations (mean ± SD) measured by the enhanced sensitivity chemiluminescence assay were lower in male than female subjects at both baseline (0.12 ± 0.08 vs. 2.3 ± 2.3 μg/L; P < 0.01) and the postglucose GH nadir (0.029 ± 0.014 vs. 0.25 ± 0.23 μg/L; P < 0.01). The high correlation between baseline and nadir GH (r = 0.82; P < 0.001) and the equivalent fractional decline in mean GH levels in men and women after glucose administration (67 ± 17% vs. 84 ± 8%; P = 0.06) suggest that the lower GH levels in men after glucose treatment are due to lower baseline values and not to a greater suppressive effect of glucose.

Original languageEnglish (US)
Pages (from-to)1312-1319
Number of pages8
JournalJournal of Clinical Endocrinology and Metabolism
Volume78
Issue number6
DOIs
StatePublished - Jun 1994

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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