Vitamin D status and lower urinary tract symptoms in children: Findings from a prospective comparative study

Vitamin D has been suggested to influence bladder function, but evidence in children remains limited and inconsistent. This study aimed to evaluate serum vitamin D levels in children with lower urinary tract symptoms (LUTS) and healthy controls and to investigate whether vitamin D was associated with LUTS severity and bladder diary parameters. A total of 244 children were included, comprising 136 children with LUTS and 108 controls. Serum 25-hydroxyvitamin D concentrations and vitamin D categories were compared between groups. Associations between vitamin D and symptom severity or bladder diary measures were evaluated within the LUTS group. Logistic regression models assessed the association between vitamin D and LUTS, with adjustment for age and sex and, in an expanded model, for age, sex, raw body mass index (BMI), and season. An age-restricted analysis of children aged 5–8 years was also performed. Median serum vitamin D concentrations were 17.15 ng/mL in the LUTS group and 16.60 ng/mL in controls ( p = 0.150), with no significant difference in vitamin D category distributions ( p = 0.277). In the unadjusted analysis, higher vitamin D was associated with LUTS (OR 1.217 per 5-ng/mL increase, 95% CI 1.012–1.464; p = 0.037); however, this association was attenuated after adjustment for age and sex (OR 1.084, 95% CI 0.891–1.318; p = 0.421). In the expanded model adjusted for age, sex, raw BMI, and season, vitamin D was not independently associated with LUTS (OR 0.971, 95% CI 0.754–1.251; p = 0.821). The age-restricted model yielded a similar result (OR 0.812, 95% CI 0.609–1.074; p = 0.144). Within the LUTS group, vitamin D showed no significant association with DVISS score, bladder capacity measures, wet-night frequency, or voiding frequency after correction for multiple comparisons. An exploratory comparison showed higher vitamin D with ≥ 8 versus ≤ 7 voids/day (18.56 vs. 17.00 ng/mL; unadjusted p = 0.037), but it was not multiplicity-adjusted and was not supported by corrected analyses. Serum vitamin D concentration was not independently associated with pediatric LUTS, symptom severity, or bladder diary parameters. Although an association was observed in the unadjusted analysis, it disappeared after adjustment for relevant covariates and was not supported by age-restricted or sensitivity analyses. These findings do not support an independent relationship between vitamin D status and LUTS in this cohort.