High prevalence of hypovitaminosis D in Mexican children with atopic dermatitis

Vitamin D has been implicated in epidermal barrier function and immune regulation, but its clinical relevance in pediatric atopic dermatitis (AD) remains uncertain. This retrospective cross-sectional study aimed to determine the prevalence of vitamin D insufficiency and deficiency in Mexican children with AD and to explore its association with disease severity in a tertiary-care setting. Patients aged 6 months to 17 years evaluated between January 2022 and January 2023 were included if they had a diagnosis of AD and an available serum 25-hydroxyvitamin D measurement. Disease severity was assessed using the SCORing Atopic Dermatitis index. A total of 423 patients were analyzed; 223 (52.7%) had mild disease, 178 (42.1%) had moderate disease, and 22 (5.2%) had severe disease. Only 23 patients (5.4%) had sufficient vitamin D levels, whereas 273 (64.5%) had insufficiency and 127 (30.0%) had deficiency. The distribution of categorical vitamin D status did not differ significantly across severity strata. Serum vitamin D levels differed modestly across severity groups, with the lowest mean concentration observed in severe disease. In the full cohort, serum vitamin D levels were not independently associated with SCORAD after age adjustment. In an exploratory analysis restricted to moderate-to-severe disease, lower vitamin D levels were associated with higher SCORAD values. Hypovitaminosis D was highly prevalent in this Mexican pediatric cohort with AD. Its relationship with disease severity appears nonuniform and should be interpreted cautiously in light of the cross-sectional design.