CHANGES IN SUBCUTANEOUS AND VISCERAL FAT MASS DURING GROWTH-HORMONE REPLACEMENT THERAPY IN ADULT MEN

OBJECTIVES: To assess the degree of subcutaneous and intraabdominal fa t accumulation in growth hormone (GH) deficient adult men, and to eval uate the lipolytic effects of GH replacement therapy. DESIGN: Placebo- controlled. double-blind, dose-response study. All patients, including those initially starting on placebo, received GH for a period of one year. SUBJECTS: 46 adult men (mean age 28.0 +/- 4.5 y) with childhood- onset GH deficiency (GHD). MEASUREMENTS: Subcutaneous fat mass and fat distribution was assessed by measurement of skinfold thicknesses at s even different sites. Intraabdominal fat mass was assessed by computer ized tomography (CT). Reference values were obtained from age- and sex -matched controls with a normal body mass index. RESULTS: The sum of s kinfolds (SKFs) was 75% (95% CI: 52-98%) higher, and intraabdominal fa t area was 84% (95% CI: 45-122%) greater in GHD patients than in age- and sex-matched controls. Patients with multiple pituitary hormone def iciencies (MPHD, n = 30), who were all receiving conventional hormone replacement therapy, were more obese than patients with isolated GHD ( IGHD, n = 16). This difference was attributed to a more severe impairm ent in GH secretion, as well as to the lower androgen levels in patien ts with MPHD. GH treatment was associated with a gradual decline in su bcutaneous fat that continued for approximately six months. Thereafter , a new steady-state was reached. The OH-induced decline in subcutaneo us and intraabdominal fat was dose-dependent (r = 0.84, p < 0.001 and r = 0.52, p < 0.001, respectively). The efficacy of GH treatment was s imilar in IGHD and MPHD patients. Optimal GH replacement, defined as t reatment resulting in normalization of serum insulin-like growth facto r-I (IGF-I) concentration, was achieved in 25 patients. In this subgro up the sum of SKFs decreased by 27% (95% CI: 22-32%) and intraabdomina l fat was reduced by 47% (95% CI: 38-57%). CONCLUSION: We conclude tha t subcutaneous as well as intraabdominal fat mass are abnormally high in GHD men, and that GH treatment with doses within the physiological range profoundly reduces the sizes of both fat compartments. In additi on, GH replacement therapy was found to be equally effective in men wi th IGHD as in those with MPHD.