Bone Abstracts

Background: Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy in children and it is well known for its progressive deteriorating course. Nowadays, use of glucocorticoids is the gold standard of treatment for this group of patients as it can significantly prolong ambulation, decrease risk of scoliosis, and pulmonary functions. However, the use of glucocorticoid is associated with increased risk of vertebral and lower limb fractures, which could further accelerate the loss of ambulatory capacity.

Objectives: To assess the bone health of DMD boys before initiation of glucocorticoid treatment, by studying their bone mineral density with dual-energy x-ray absorptiometry (DXA) scan, and checking the 25-hydroxy vitamin D level and past history of fractures in a single center.

Methods: Information was gathered through retrospective medical chart review for the DMD patients that have been actively followed up between the periods from January 2009 to January 2015 in our department.

Results: Results from 18 DMD boys (mean age: 6.2 years, age range: 3–10.9 years) were evaluated. None of them had any history of long bone fracture. 14 were walking well independently, three were at the late ambulatory state and one was non-ambulatory. 14 of these patients had bone mineral density assessment and their mean z-score was −1.5 (range: −3.9–1). Five patients (36%) had low bone mineral density for age with z-score <−2. Vitamin D status was assessed in 16 patients and 13 of them (81%) were found to have vitamin D insufficiency with 25-hydroxy vitamin D level less than 50 nmol/l (mean: 40.5 nmol/l, range: 20–58 nmol/l).

Conclusion: Vitamin D insufficiency and low bone mineral density are common among DMD boys even before initiation of glucocorticoids. The use of long-term steroid will further increase bone loss in this already-at-risk group. More effective forms of bone protective strategy, including bisphosphonates prophylaxis, should be considered among this group of patients.

Disclosure: The authors declared no competing interests.