The Inter- and Intra-Subject Variabilities of Plasma GH Response to Human Growth Hormone-Releasing Hormone (1-44) NH₂ in Men

抄録

The effects of intravenously given human growth hormone-releasing hormone (1-44) NH₂ (hGRH-44) on growth hormone (GH) secretion were studied in normal men.
A wide variability of intersubject GH response to hGRH-44 was observed. The peak plasma GH levels in response to 50, 100 and 200μg hGRH-44 in 7 normal men were 9.1±3.2ng/ml (Mean+SEM), 19.3±3.3ng/ml and 22.4±4.0 ng/ml, respectively. Both the mean peak values for plasma GH response to 100 and 200μg were significantly greater than that for 50μg hGRH-44 injection (p<0.01), although there was no significant difference of the mean peak plasma GH values and mean concentrations at each time point, except for those at 120min, when 100 or 200μg hGRH-44 was administered. A significant difference in the mean amount of plasma GH secreted in response to hGRH-44 was observed only between 50 and 200μg hGRH-44 injection (p<0.01). Furthermore, a dose-related plasma GH increase in response to hGRH-44 was not always observed in each subject.
In contrast to the wide intersubject variability, the difference among responses of plasma GH to 100μg or 200μg of hGRH-44 given at multiple times separated by intervals of at least 1 week in each individual was relatively small.
These results suggest that the wide intersubject variability could cause no dose-related GH response to hGRH-44 in doses of 50, 100 and 200μg and that the intrasubject variability was small enough to evaluate the GH secretion by a single hGRH-44 injection, a procedure not adopted before.