Retrospective Serologic Assessment of Vitamin D Levels in Children from Western Romania: A Cross-Sectional Study.

Adequate levels of vitamin D are vital for both growth and immunomodulation in children. To evaluate the levels of vitamin D in children from Western Romania and to identify significant age, seasonal, and geographical disparities. This study evaluates the level of 25-hydroxyvitamin D levels assessed on Cobas 6000's module e601 in 1698 children aged 1-18 years between 1 January 2018 and 31 December 2021 from Western Romania. : Children aged 1-6 years predominantly present sufficient levels (>30 ng/mL), while older age groups showed a marked decline. Adolescents aged 13-18 years were most affected, with over half displaying insufficient levels (20-30 ng/mL). Rural children were more likely to achieve sufficiency compared to urban peers. Males demonstrated significantly higher vitamin D levels when compared to females. Seasonal variations showed the highest vitamin D levels during late summer and early autumn (September: aOR = 5.47; 95% CI: 3.17-9.42, < 0.001). Multivariate analysis revealed a significant improvement in vitamin D levels during 2019-2020. : Our findings suggest the need for targeted screening programs and health policies to address vitamin D deficiency, particularly among older children, urban residents and during winter months.