A prospective study of 5 years of GH replacement therapy in GH-deficient adults: Sustained effects on body composition, bone mass, and metabolic indices

GH replacement therapy has proved its efficacy and safety in short-term tri als and in a few long-term trials with limited number of subjects. In this 1-center study, including 118 consecutive adults (70 men and 48 women; mean age, 49.3 yr; range, 22-74 yr) with adult-onset GH deficiency, the effects of 5 yr of GH replacement on body composition, bone mass, and metabolic in dices were determined. The mean initial GH dose was 0.98 mg/d. The dose was gradually lowered, and after 5 yr the mean dose was 0.48 mg/d. The mean IGF-I SD score increased from -1.73 at baseline to 1.66 at study end. A sustained increase in lean b ody mass and a decrease in body fat were observed. The GH treatment increas ed total body bone mineral content as well as lumbar (L2-L4) and femur neck bone mineral contents. BMD in lumbar spine (L2-L4) and femur neck were inc reased and normalized at study end. Total cholesterol and low density lipop rotein cholesterol decreased, and high density lipoprotein cholesterol incr eased. At 5 yr, serum concentrations of triglycerides and hemoglobin A(1c) were reduced compared with baseline values. The treatment responses in IGF- I SD score, body fat as estimated by four- and five-compartment body compos ition models, total body protein and nitrogen, and lumbar bone mineral cont ent and BMD were more marked in men than in women. One patient died during the period, four patients discontinued the study du e to adverse events, and one dropped out due to lack of compliance. Four pa tients were lost to follow-up. However, all patients were retained in the s tatistical analysis according to the intention to treat approach used. In conclusion, 5 yr of GH substitution in GH-deficient adults is safe and w ell tolerated. The effects on body composition, bone mass, and metabolic in dices were sustained. The effects on body composition and low density lipop rotein cholesterol were seen after 1 yr, whereas the effects on bone mass, triglycerides, and hemoglobin A(1c) were first observed after years of trea tment.