Serum 25-hydroxyvitamin D concentrations in girls aged 4–8 y living in the southeastern United States

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Abstract
Background: Evidence suggests that adults and adolescents throughout the United States are at risk of poor vitamin D status. However, vitamin D concentrations in young American children have not been assessed. Objective: The relations between serum 25-hydroxyvitamin D [25(OH)D] and bone were examined in prepubertal girls. Design: In the present cross-sectional study, serum 25(OH)D concentration was assessed in 168 prepubertal girls aged 4–8 y living in the southeastern United States with the use of radioimmunoassay. Bone area, bone mineral content, and areal bone mineral density were measured from total body, lumbar spine, proximal femur, and forearm with dual-energy X-ray absorptiometry. Data were analyzed with analysis of variance, analysis of covariance, stepwise multiple regression, and partial correlations. Results: The mean (±SD) serum 25(OH)D was 93.8 ± 28.1 nmol/L (range: 31.1–181.4 nmol/L). In a multiple regression analysis, race and season were the strongest predictors of vitamin D status. The black girls had lower mean 25(OH)D values than did the white girls (P < 0.01), and 25(OH)D values were significantly different in the total sample between the seasons (P < 0.001), ranging from 74.4 nmol/L during the winter months to 107 nmol/L during the summer. After adjustment for season, age, race, and body mass index, 25(OH)D values were negatively correlated with forearm bone mineral content (r = −0.18; P = 0.02). Conclusions: Unlike prior reports of adults and adolescents living in the southeastern United States, vitamin D status was adequate in the children of the present study. 25(OH)D concentrations were not positively associated with higher bone mineral.