TRABECULAR BONE SCORE CHANGE DIFFERS WITH REGRAD TO 25(OH)D LEVELS IN PATIENTS TREATED FOR ADULT-ONSET GROWTH HORMONE DEFICIENCY

Objective: Vitamin D is important in bone health. However, potential relationships of concomitant vitamin D deficiency with growth hormone deficiency (GHD) and the possibility that vitamin D inadequacy may alter the skeletal effects of growth hormone (GH) replacement therapy have not been adequately evaluated. Methods: A prospective study was conducted in adult-onset GHD patients treated with recombinant human GH (rhGH) for 2 years. Trabecular bone score (TBS), lumbar spine (LS) bone mineral density (BMD), total hip (TH) BMD, and 25-hydroxyvitamin D (25(OH)D) levels were assessed at baseline and 24 months. The study cohort was divided based on 25( OH) D levels into 2 groups with the cutoff defined as the 50th percentile at each follow-up time point. Results: Fifty-seven patients (29 males/28 females, mean age 34.4 years) were studied. After 24 months of GH replacement, LS BMD increased by 7.6% and TH BMD increased by 4.5% (both P<.05), with no difference according to 25(OH)D levels. TBS increased (+1.39 +/- 3.6%) in those whose 25(OH)D was above the 50th percentile but decreased (-1.36 +/- 5.6%, P<.05) in the cohort below the 50th percentile of 25(OH)D. Positive correlations were observed between baseline levels of IGF-1 and 25(OH)D (R = 0.37, P<.001) and between 24-month 25(OH)D and TBS (R = 0.25, P<.05). Conclusion: A differential effect of GH on TBS change was observed; TBS increased only in the cohort with 25(OH)D above the 50th percentile. Vitamin D sufficiency may be required to obtain optimal effects of GH treatment on bone quality, as assessed by TBS, in GHD adults.