Efficacy of Vitamin D Supplementation in Children with Transfusion Dependent Thalassemia

Hypovitaminosis D is common in children with transfusion-dependent thalassemia (TDT) because of chronic iron overload and endocrine dysfunction. This study assessed baseline vitamin D status, response to supplementation, and factors associated with treatment response and maintenance of sufficiency.

In this prospective observational study, children aged 1-18 y with TDT underwent assessment of demographic, clinical, biochemical, and serum 25-hydroxyvitamin D levels. Vitamin D deficiency, insufficiency, and sufficiency were defined as <12 ng/mL, 12-20 ng/mL, and >20 ng/mL, respectively. Children with deficient or insufficient levels received oral vitamin D (60,000 IU weekly for 6 wk) with calcium supplementation. Vitamin D levels were reassessed after 3 mo; non-responders received repeat supplementation, while responders were followed for maintenance of sufficiency.

Among 93 children, 89 (95.7%) had hypovitaminosis D, with a mean baseline vitamin D level of 11.63 ± 5.66 ng/mL. Following supplementation, 60 (67.4%) achieved sufficiency, while 29 (32.6%) remained deficient/insufficient. Of those achieving sufficiency, only 14 (23.3%) maintained adequate levels at 3-mo follow-up, whereas 46 (76.7%) again became deficient/insufficient. Repeat supplementation resulted in sufficiency in 20/29 (69.0%) children. Baseline vitamin D levels showed a significant negative correlation with serum ferritin (ρ = -0.664, p <0.001).

Hypovitaminosis D is highly prevalent in children with TDT and is strongly associated with iron overload. Although supplementation effectively improves vitamin D levels, maintenance of sufficiency after discontinuation remains poor, emphasizing the need for regular monitoring and maintenance supplementation.