Prevalence of vitamin D deficiency in children with iron-deficiency anaemia: A hospital-based cross-sectional study

Objectives: Anaemia due to iron deficiency is among the leading nutritional disorders affecting children in resource-limited settings, particularly in middle- and low-income countries. Vitamin D deficiency (VDD), while often remaining clinically silent, is now recognised to exert important extra-skeletal functions, notably in regulating erythropoiesis and iron homeostasis. An expanding body of literature points to a bidirectional and mechanistically complex relationship between iron nutritional status and vitamin D metabolism. The aim of the study is to assess the prevalence of VDD among children with a confirmed diagnosis of iron-deficiency anaemia. Material and Methods: A hospital-based cross-sectional study was undertaken at the Paediatrics department, Sri Chamundeshwari Medical College Hospital and Research Institute, Channapatna, Karnataka, India, over a 1-year period spanning December 2024–November 2025. One hundred children under 15 years of age with confirmed iron-deficiency anaemia were enrolled. Serum 25-hydroxyvitamin D concentrations were quantified by chemiluminescence immunoassay. Vitamin D status was categorised as deficient (<12 ng/mL), insufficient (12–20 ng/mL) or sufficient (>20 ng/mL). Associations between vitamin D status and demographic variables were assessed using the Chi-square test. Results: Among the 100 children studied, 94% (95% confidence interval [CI]: 87.5–97.2%) were younger than 5 years of age, with males accounting for 63% (95% CI: 53.2–71.8%) of participants. VDD was identified in 4% (95% CI: 1.6–9.8%) of children, while 36% (95% CI: 27.3–45.8%) had vitamin D insufficiency, bringing the total proportion with suboptimal vitamin D levels to 40% (95% CI: 30.9–49.8%). No significant association was found between vitamin D status and sex (χ 2 = 0.12; p = 0.94) or age group (χ 2 = 0.48; p = 0.98). As all participants had confirmed iron-deficiency anaemia and no non-anaemic comparison group was included, these findings describe the prevalence of suboptimal vitamin D within this population rather than an association between the two conditions. Conclusion: Two-fifths of children diagnosed with iron-deficiency anaemia had suboptimal vitamin D levels. Given the descriptive, single-centre design and the absence of a comparison group, these findings should be regarded as hypothesis-generating rather than conclusive, and prospective multicentre studies are needed before routine vitamin D screening can be recommended for children with iron-deficiency anaemia.