Gender difference in the response of growth hormone (GH)-deficient adults to GH therapy

While individual hypopituitary patients undoubtedly benefit from growth hor mone (GH) therapy, there is considerable variability in the response to tre atment. Given the expense, possible lack of benefit, end potential risks as sociated with long-term therapy, we sought to identify characteristics pote ntially associated with a favorable response to GH replacement. Twelve GH-d eficient adults (seven men and five women aged 35.4 +/- 2.5 years, mean +/- SEM) participated in a 12-month open study of GH replacement (0.125 IU/kg/ wk for 4 weeks and 0.25 IU/kg/wk thereafter) designed to examine the impact of GH on body composition, lipid profile, and psychological well-being. Us ing bioelectrical impedance analysis (BIA), there was a reduction in body f at (BF) and an increase in lean body mass (LBM) and total body water (TBW) (P < .05) following 12 months of GH treatment. In addition, there was a sig nificant improvement in psychological well-being as indicated by a decrease in the Nottingham Health Profile (NHP) score (P < .05) and a decrease in b oth total cholesterol (P = .005) and low-density lipoprotein (LDL) choleste rol (P < .03). GH therapy was associated with an increase in fasting plasma glucose (P = .008) and hemoglobin A(1c) (HbA(1c) (P = .06). When analyzed by gender, the beneficial effect of GH was greater in men versus women for the increment in insulin-like growth factor-1 ([IGF-1] 375 +/- 59 v 148 +/- 73 mu g/L, mean +/- SEM), increase in LBM (6.8 +/- 2.5 v -0.06 +/- 1.6 kg) , reduction in BF (5.6 +/- 1.6 v 1.0 +/- 1.9 kg), and increase in TBW (5.0 +/- 1.6 v 0.14 +/- 1.29 L) (P < .05). HbA(1c) increased significantly in wo men (P < .05). The beneficial effect of GH tended to be greatest in those w ith the most significant abnormality in baseline values (P < .05). The dura tion of hypopituitarism showed an indirect correlation with the change in t otal cholesterol (P < .005). Baseline IGF-1 levels correlated directly with changes in TBW (P < .05). These data indicate that men with GH deficiency appear more responsive to GH therapy than women with respect to the increas e in IGF-I levels and improvement in body composition. In general, patients with the most significant abnormality in baseline values, the highest IGF- 1 levels, and the shortest duration of hypopituitarism respond best. With l ong-term GH therapy, careful monitoring of glucose tolerance is indicated. Copyright (C) 1999 by W.B. Saunders Company.