Long-term effects of growth hormone (GH) replacement in men with childhood-onset GH deficiency

Short term GH replacement therapy has been shown to improve body compositio n and exercise capacity. It is not yet known whether GH replacement remains beneficial over the long term. We assessed the effects of long term GH rep lacement on body composition, bone mineral density, and cardiac function. T hirty-eight men with childhood-onset GH deficiency were studied for a perio d of 3-5 yr. Measurements included anthropometry, computed tomographic scan ning of abdomen and upper leg, bone densitometry, echo cardiography, and bi cycle ergometry. The initial GH dose of 1-3 IU/m(2)-.day (9-27 mu g/kg) was gradually tapered to 1.30 +/- 0.38 IU/m(2) day (11 g/kg), aiming at physio logical insulinn-like growth factor I levels. During the study, leg muscle mass progressively increased by 28.7% (P < 0.001.). cutaneous and intraabdo minal fat decreased by 30.9% and 46.0%, respectively, after 1 yr (both P < 0.001), but demonstrated a partial regain thereafter. Bone mineral density at the lumbar spine, femoral neck, and trochanter gradually increased by 9. 6%, 11.1%, and 16.2%, respectively tall(P < 0.001). Left ventricular mass e xceeded baseline values by 14.1% after 1 yr (P < 0.001), but returned to pr etreatment values thereafter. Stroke volume and cardiac output increased by 16.3% (P = 0.002) and 33.4% (P < 0.001), respectively. Maximal work load i ncreased from 189 +/- 30 to 232 +/- 41 watts (P < 0.001). Thus,long term GH replacement is safe and beneficial. It improves cardiac performance withou t inducing left ventricular hypertrophy and progressively increases bone mi neral density.