Bone Abstracts

Background: Adult GH Deficiency (GHD) is associated with decreased bone mass and increased fracture risk. Recombinant human GH (rhGH) replacement therapy leads to progressive increases in bone mineral density (BMD) for up to 7 years of treatment, but little is known on longer term effects of rhGH therapy on bone mass or fracture risk.

Methods: 230 GHD patients (mean age 47.1 years, 52.6% female) on rhGH replacement therapy for ≥5 years were included in the study. BMD measurements were evaluated at the lumbar spine (LS) and femoral neck (FN) at baseline and at 5, 10 and 15 years after start of therapy. Clinical fracture incidence was also assessed over the period of follow-up. All patients received hormone replacement therapy for other pituitary deficiencies and calcium and/or vitamin D supplements as required, and a number additional bisphosphonate treatment.

Results: 211 patients completed 5 years, 98 patients 10 years, and 43 patients 15 years of rhGH therapy. Ten patients (4.3%) received bisphosphonates at baseline and 12.2, 19.4 and 18.6% received these agents after respectively 5, 10 and 15 years of starting rhGH. Mean duration of treatment with bisphosphonates was 6.9±4.3 years. Mean LS BMD remained stable in women, but demonstrated a significant 4% increase in men after 15 years of rhGH therapy. There was no additional benefit of bisphosphonate therapy on BMD. 15 patients (7%) sustained a clinical vertebral fracture during follow-up. the incidence rate of fractures during rhGH replacement was 46/2288.5 (mean duration of rhGH therapy 9.95 years ×230 patients) =20.1/1000 py in our GHD cohort.

Conclusions: In adult GHD, longterm rhGH replacement therapy stabilises BMD. Bisphosphonate therapy does not appear to confer additional beneficial effects on BMD or fracture risk.