ESPE Abstracts

Background: Boys affected with Duchenne Muscular Dystrophy (DMD) have lower bone mineral density compared with unaffected boys.

Objective and hypotheses: We sought to determine the effects on bone mineral density (BMD) of 1 year treatment with Risedronate and calcium/vitamin D supplementation vs calcium/vitamin D supplementation alone.

Method: BMD was measured at spine and whole body. We obtained early morning fasting blood samples for 25-hydroxyvitamin D (25OHD), calcium, parathyroid hormone (PTH), procollagen type I N-terminal propeptide (PINP), and timed-urine for N-terminal telopeptides of type I collagen (NTX). Eligible patients (spine Z-score <−1.0) were randomized to each treatment arm: Risedronate 1 mg/kg per week (max 35 μg) and calcium (500 mg/day) and vitamin D (10 μg/day), or calcium/vitamin D alone. Tests were repeated after 12 months.

Results: Twenty-nine of 62 patients were eligible; 13 consented; six were in the Risedronate arm. Nine were ambulant and were on steroid therapy. Median (range) at entry for the entire group for age was 8.5 (5.4–15.5) years, for 25OHD was 41.3 (21.5–64.4) nmol/l, for PINP was 540 (149–788) ug/l, and for NTX was 927 (361.8–2332.9) nMBCE/mMCr. In the Risedronate group: median (range) spine Z-score at baseline was −1.75 (−1.2 to −3.5), and at 12 months was −0.8 (−1.7 to 0); whole body Z-score was −1.95 (−0.5 to +2.7) and at 12 months was 1.3 (−1.0 to 2.5). In the control group: mean spine Z-score at baseline was −2.2 (−4.1 to −1.2) and at 12 months was −1.6 (−8.4 to −0.8), whole body Z-score at baseline was −1.2 (−1.6 to +4.7) and at 12 months was −0.8 (−3.1 to 3). There was no significant change in PINP or NTX after 12 months in either group.

Conclusion: We demonstrated a significant improvement in BMD at spine and whole body at 12 months in the Risedronate group. Bone resorption marker was increased with respect to bone formation marker. This pilot study suggests benefit of Risedronate therapy, but would need validation in a larger study.

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