Low bone density and bone metabolism alterations in Duchenne muscular dystrophy: response to calcium and vitamin D treatment

Summary

Boys with Duchenne muscular dystrophy often have reduced bone mass and increased fracture risk. In this prospective study on 33 patients, calcifediol (25-OH vitamin D₃) plus adjustment of dietary calcium to the recommended dose reduced bone resorption, corrected vitamin D deficiency, and increased bone mass in about two-thirds of cases.

Introduction

Low BMC and BMD and bone metabolism alterations are frequent in boys with Duchenne muscular dystrophy (DMD), especially now that long-term glucocorticosteroid (GC) treatment is the standard of care. This prospective study was designed to evaluate the effects of a first-line treatment (25-OH vitamin D₃ calcifediol] plus adjustment of dietary calcium to the recommended daily dose) on bone.

Methods

Thirty-three children with DMD on GC treatment were followed for 3?years: one of observation and two of treatment. Main outcome: spine and total body BMC and BMD increase; secondary outcome: changes in bone turnover markers (C-terminal CTx] and N-terminal NTx] telopeptides of procollagen type I; osteocalcin OC]).

Results

During the observation year, BMC and BMD decreased in all patients. At baseline and after 12?months, serum CTx and urinary NTx were higher than normal; OC and parathyroid hormone at the upper limit of normal; 25-OH vitamin D₃ significantly lower than normal. After 2?years of calcifediol and calcium-rich diet, BMC and BMD significantly increased in over 65% of patients, and bone metabolism parameters and turnover markers normalized in most patients (78.8%). During the observation year, there were four fractures in four patients, while during the 2?years of treatment there were two fractures in two patients.

Conclusions

Calcifediol plus adequate dietary calcium intake seems to be an effective first-line approach that controls bone turnover, corrects vitamin D deficiency, and increases BMC and BMD in most patients with DMD. Lack of response seems related to persistently high bone turnover.