ESPE Abstracts

Context: Severe vitamin D deficiency may lead to myopathy in adults. Little is known about vitamin D and muscle strength in children.

Objective: To test whether hand grip strength (HGS) in 5-year-old-children associates with serum 25-hydroxyvitamin D (s-25OHD) from pregnancy to 5 years.

Methods: Observational study in the population-based Odense Child Cohort, Denmark. At 5 years, anthropometrics, body fat percentage by skin fold measurements and HGS were obtained (n=881). Myopathy was defined as HGS <10^th percentile. S-25OHD₂₊₃ was analyzed with liquid chromatography mass spectrometry (5-y; n=499).

Results: Mean (S.D.) HGS was higher for boys compared to girls, 8.76 (1.76) vs 8.1 (1.64) kg, P<0.001. Mean (S.D.) 5-year s-25OHD was 70.7 (24.5) nmol/l. HGS was directly associated with height in girls, and with weight (directly) and body fat percentage (inversely) in both sexes (P<0.01 for all). In girls, 5-year s-25OHD was associated with HGS, adjusting for height, weight and body fat percentage, β=0.011 (95% CI 0.004;0.019), P=0.003. S-25OHD ≥75 nmol/l associated with higher HGS compared to values <50 nmol/l, adjusted β=0.783 (0.325;1.241), P=0.001. The odds of having myopathy were reduced by approximately 70% for s-25OHD ≥50 vs <50 nmol/l, adjusted odds ratio 0.310 (95% CI 0.126;0.762), P=0.011. No associations were seen for boys. S-25OHD at other time points did not associate with 5-year HGS.

Conclusions: Five-year s-25OHD was independently associated with HGS and myopathy in girls, but not in boys. Muscle strength may be dependent on vitamin D status even in the higher range in preschool girls. The sex difference remains unexplained.