Reproducibility and variability of the arginine test in normal adults. Comparison between sexes.

摘要: The biochemical diagnosis of growth hormone deficiency in adults (AGHD) remains controversial, mainly as regards stimulation tests and suggested cut-off lines. insulin tolerance test proved to be the most effective (GH) secretagogue normal males, but a poor intra-individual reproducibility has been reported. Given safety arginine (AST), we decided evaluate incidence false negatives (non responder subjects), its variability. Twenty five healthy non-obese volunteers (16 9 females) with chronological age range between 19 40 years, (mean: 29.8) were evaluated. AST was performed (0.5 g/kg IV infusion for 30 min), measuring GH (IRMA) at baseline (B), 30, 60 90 minutes, it repeated same subject 7 days later; females both early follicular phase. Results (median range) were: 1st B: 0.61 (0.35-22.60) µg/L; maximal response (Mx Resp) 10.00 (0.48-48.80) µg/L. 2nd 0.50 (0.38-27.0) Mx Resp 11.00 (0.50-47.70) statistical evalu- ation (Wilcoxon signed rank test) showed no differences B vs. vs Resp. Separated by sex, males showed: test: 0.45 (0.35-4.30) 6.30 0.46 (0.38-8.80) 10.90 µg/L, while 5.20 (0.50-22.60) mx 14.00 (3.50-36.70) 3.60 (0.75-27.00) 13.00 (3.70-28.10) comparison (Mann Whitney significant sexes basal values first second (p < 0.001), 0.03). analysis did not show delta increases females, neither nor one. Consid- ering ≥ 3 µg/L positive response, 4 exhibited insufficient responses other 2 discordant results 1 2. All evaluated produced above µg/ L tests. present study demonstrate that, particularly men, clear limit normality shows good reproducibility. In conclusion, AGHD requires precise standardization which includes all variables that can modify stimulus used.