Impact of Adequate Day 30 Post-Pediatric Hematopoietic Stem Cell Transplantation Vitamin D Level on Clinical Outcome: An Observational Cohort Study

This prospective observational study evaluated the impact of adequate vitamin D levels by day +30 after vitamin D supplementation on early post-HSCT outcomes, including acute graft-versus-host disease (aGVHD), immune recovery, infection rates, and overall survival. Forty children (age 2 to 16 years) undergoing hematopoietic stem cell transplantation (HSCT) were given vitamin D supplementation, were followed prospectively from day +30 post-transplantation, and had day +30 vitamin D levels measured. Thirty patients with normal vitamin D levels (≥30 ng/mL) were compared with 10 patients with low day +30 vitamin D levels (<30 ng/mL). The times to neutrophil and platelet engraftment was similar in both day +30 vitamin D groups (P = .13 and .32, respectively). At day +100, slower immune recovery in CD4⁺ cells (P = .027), CD19⁺ cells (P = .024), and natural killer cells (P = .042) was observed in the patients with a low vitamin D level (<30 ng/mL), and no between-group differences were detected in the incidence of infection (P = .72) or grade II-IV aGVHD (P = .46). Our findings show that patients with adequate vitamin D levels during transplantation had faster immune recovery and better overall survival. Vitamin D deficiency does not appear to impact engraftment or the risk of aGVHD and infection in pediatric HSCT.