Effects of 3-year GH replacement therapy on bone mineral density in younger and elderly adults with adult-onset GH deficiency

Objective: Little is known of the effects of long-term GH replacement on bone mineral content (BMC) and bone mineral density (BMD) in elderly GH-deficient (GHD) adults. Design/patients/methods: In this prospective, single-center, open-label study, the effects of 3-year GH replacement were determined in 45 GHD patients>65 years and in 45 younger control GHD patients with a mean age of 39.5 (S. E. M. 1.1) years. All patients had adult-onset disease and both groups were comparable in terms of number of anterior pituitary hormonal deficiencies, gender, body mass index, and waist: hip ratio. Results: The mean maintenance dose of GH was 0.24 (0.02) mg/day in the elderly patients and 0.33 (0.02) mg/day in the younger GHD patients (P<0.01). The 3 years of GH replacement induced a marginal effect on total body BMC and BMD, whereas femur neck and lumbar (L2-L4) spine BMC and BMD increased in both the elderly and the younger patients. The treatment response in femur neck BMC was less marked in the elderly patients (P<0.05 vs younger group). However, this difference disappeared after correction for the lower dose of GH in the elderly patients using an analysis of covariance. There were no between-group differences in responsiveness in BMC or BMD at other skeletal locations. Conclusions: This study shows that GH replacement increases lumbar (L2-L4) spine and femur neck BMD and BMC in younger as well as elderly GHD patients. This supports the notion that long-term GH replacement is also useful in elderly GHD patients.