Differential Effects of Raloxifene and Estrogen on Body Composition in Growth Hormone-Replaced Hypopituitary Women

Context: GH deficiency causes reduction in muscle and bone mass and an increase in fat mass (FM), the changes reversed by GH replacement. The beneficial effects of GH on fat oxidation and protein anabolism are attenuated more markedly by raloxifene, a selective estrogen receptor modulator, compared with 17β-estradiol. Whether this translates to a long-term detrimental effect on body composition is unknown. Objective: Our objective was to compare the effects of 17β-estradiol and raloxifene on FM, lean body mass (LBM), and bone mineral density (BMD) during GH replacement. Design: This was an open-label randomized crossover study. Patients and intervention: Sixteen hypopituitary women received GH (0.5 mg/d) replacement for 24 months. One group received 17β-estradiol (2 mg/d) for the first 6 months before crossover to raloxifene (60 mg/d) for the remaining 18 months; the other received the reversed sequence. Main Outcome Measures: Serum IGF-I and IGF-binding protein-3 concentrations, and FM, LBM, lumbar spine...