Relationships between 25-hydroxyvitamin D and nocturnal enuresis in five- to seven-year-old children.

BACKGROUND: Vitamin D has been recognized to contribute to various physiological processes. However, no study has investigated serum 25-hydroxyvitamin D [25(OH)D] concentrations in children with nocturnal enuresis (NE) in the English literature. OBJECTIVE: In the present study, serum 25(OH)D concentrations were measured in five- to seven-year-old children with NE and compared with those in non-enuretic children to investigate whether there was any relationship between 25(OH)D and NE as the first time in the literature. DESIGN: Two hundred forty-seven five- to seven-year-old children were recruited from Taizhou, Zhejiang Province, China. Serum 25(OH)D concentrations were measured, and the structured questionnaire was administered to the parents of all children. Low 25(OH)D was defined as serum 25(OH)D concentrations below 20 ng/ml. RESULTS: The prevalence of NE was 7.3% in the group of children with 25(OH)D concentrations that exceeded 20 ng/ml; this prevalence was much lower than the 17.5% observed in the group of children with 25(OH)D concentrations below 20 ng/ml (p<0.05). After adjusting for potential confounders, serum 25(OH)D (≥20 ng/ml) was significantly associated with NE and represented a protective factor against NE (OR = 0.31, 95%CI = 0.092, 1.0, P<0.05). A nonlinear relationship between 25(OH)D and NE was observed. The prevalence of NE decreased with increasing 25(OH)D concentrations above 19 ng/ml. Additionally, children exhibiting higher frequencies of bedwetting had lower 25(OH)D concentrations [5-7 times/week: 18.3±4.8; 2-4 times/week: 20.9±4.1; 0-1 times/week: 23.6±6.4 (ng/ml), P<0.05)]. CONCLUSIONS: Low 25(OH)D was associated with an increased risk of NE in children aged five to seven years.