Nickan Research Institute Journal of Parathyroid Disease 2345-6558 13 1 2025 01 01 Vitamin D deficiency in children with urinary tract infection; a systematic review and meta-analysis e13301 e13301 10.34172/jpd.2025.13301 EN Mehrnaz Nazari Rad https://orcid.org/0009-0003-8341-8153 Hamid Rastad https://orcid.org/0009-0003-9322-0394 Leila Ashrafi https://orcid.org/0000-0001-5204-2825 Sara Ghaseminejad Kermani https://orcid.org/0000-0002-1730-8437 Kamran Safa https://orcid.org/0000-0002-3630-5418 Sina Salem Ahim https://orcid.org/0009-0008-2452-434X Roozbeh Roohinezhad https://orcid.org/0000-0002-0866-2047 Rasoul Jafari Arismani https://orcid.org/0000-0001-7440-0507 Baharak Maddahi https://orcid.org/0000-0002-6067-8011 Journal Article 10.34172/jpd.2025.13301 2025 07 16 2025 09 13 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.