Vitamin D deficiency in children with urinary tract infection; a systematic review and meta-analysis

Introduction: Urinary tract infection (UTI) is among the most common bacterial infections in children, and evidently, it is associated with vitamin D deficiency. Accordingly, the present study intended to examine the frequency of vitamin D deficiency in children with UTI. Materials and Methods: Databases Scopus, PubMed, Embase, Web of Science, Cochrane, and Google Scholar Search Engine were used for articles published until August 1, 2025. Data was analyzed using STATA 14. Tests with P values <0.05 were considered statistically significant. Results: The frequency of vitamin D deficiency in the total population of children with UTI was, in case-control studies, and in cohort studies were 42%, 44%, and 38%, respectively. Furthermore, the rates of vitamin D deficiency in children with UTI aged under 3 years, those aged 3 to 5 years, and children older than 5 years were 21%, 46%, and 71%, respectively. Additionally, vitamin D insufficiency frequency in the total population of children with UTI, in case-control studies, and cross-sectional studies was 30%, 34%, and 22%, respectively. Moreover, the rates of vitamin D insufficiency in children with UTI aged under 3 years and those aged 3 to 5 years were 30% and 33%, respectively. Vitamin D deficiency was observed in 60% of the girls and 42% of the boys with UTI. Approximately 47% of the Asian and 20% of the European children with UTI suffered from vitamin D deficiency, and the frequency of vitamin D insufficiency in Asian and European children with UTI was 34% and 24%, respectively. Conclusion: Approximately half of the children with UTI suffered from vitamin D deficiency, and one-third of them faced vitamin D insufficiency. The increase in the age of the children added to the percentage of children with vitamin D deficiency or insufficiency. Furthermore, Asian children were at higher risk compared with European children, and females were exposed to higher risks than males. Registration: This study has been compiled based on the PRISMA checklist, and its protocol was registered on the PROSPERO (ID: CRD420251122224) and Research Registry (UIN: reviewregistry2033) websites.