Short stature in Duchenne muscular dystrophy: a study of 34 patients

In Duchenne muscular dystrophy (DMD), short stature is a feature of unknown cause. This cross-sectional study of 34 male patients (mean age 8.0 y, age range 1.2-13.7 y) was conducted to examine the relationship between auxolo gical parameters, markers of growth and the extent of muscular weakness. We ight and length at birth (SDS +/- SD; 0.0 +/- 1.2; 0.2 +/- 1.5) and target height SDS (-0.2 +/- 0.7) were normal. Height (HT) SDS (-1.0 +/- 1.1) was l ower than the normal population (p < 0.001) and did not correlate with age. Body mass index SDS (-0.1 +/- 1.6) was normal. Tests of insulin-like growt h factor-I SDS (-0.6 +/- 1.2) and insulin-like growth factor binding protei n-3 SDS (0.1 +/- 1.3) ruled out a severe derangement in the GH-IGF-axis. Th e carboxy-terminal propeptide of type I procollagen (PICP) SDS (0.6 +/- 1.5 ) was normal, but bone-specific alkaline phosphatase (BAP) SDS (-1.7 +/- 0. 8) was low (p < 0.001). HT SDS did not correlate with BAP SDS. The Vignos s cale, a grading of muscular function (score: 0 = unaffected; 11 = confined to bed) (median (range): 3 (0-9)) correlated strongly with age (r = 0.77, p < 0.0001), but did not correlate with PIT SDS, PICP SDS or BAP SDS. In con clusion, DMD patients are significantly shorter than the normal population. though the PIT SDS does not change with age. Growth hormone deficiency doe s not seem to be the cause of short stature in DMD. Significantly low BAP l evers are probably the result of the reduced muscle mass, which leads to a lower biomechanical load on the bone and thus a reduction in bone turnover. The short stature observed in our study is unlikely to be the result of mu scular weakness.