Endocrine Abstracts

Objective: Few studies have determined the effects of more than 5–10 years of GH replacement in adults on bone mass and density.

Design/patients: In this prospective, single-centre, open-label study, the effects of 15 years of GH replacement on bone mineral content (BMC) and bone mineral density (BMD) were determined in 126 hypopituitary adults (72 men) with adult onset GH deficiency (GHD). Mean age was 49.4 (range 22–74) years at study start. BMC and BMD were measured using dual X-ray absorptiometry (DXA).

Results: The mean initial GH dose of 0.63 (S.E.M. 0.03) mg/day was gradually lowered and after 15 years the mean dose was 0.41 (0.01) mg/day. The mean serum insulin-like growth factor 1 (IGF1) SDS increased from −1.69 (0.11) at baseline to 0.63 (0.16) at study end (P<0.001 versus baseline). The 15 years of GH replacement induced a sustained increase in total body BMC (+5%; P<0.001) and BMD (+2%; P<0.001). Lumbar (L2–L4) spine BMC was increased by 9% (P<0.001) and BMD by 5% (P<0.001). In femur neck a peak increase in BMC and BMD of 7 and 3% respectively was observed after 7 years (both P<0.001). After 15 years, femur neck BMC was still 5% above the baseline value (P<0.05), whereas femur neck BMD had returned to the baseline level. In most variables reflecting bone mass and density, men had a more marked response to GH replacement than women.

Conclusions: Fifteen-year GH replacement in GHD adults induced a sustained increase in total body and lumbar (L2–L4) spine BMC and BMD. In the femur neck, BMC and BMD increased progressively up to 7 years and then slightly, but not fully, decreased towards baseline values.