Vitamin d levels affect outcome in pediatric hematopoietic stem cell transplantation.

The importance of vitamin D in immunologic processes has recently emerged, but whether it has any impact on the course of allogeneic hematopoietic stem cell transplantation (HSCT) has not been determined. Reports indicate that HSCT recipients, particularly children, often suffer from vitamin D deficiency. This study investigated the role of vitamin D in 123 children undergoing HSCT from 2004 to 2011. Vitamin D (ie, serum calcidiol) was analyzed in collected cryostored samples. Patients were grouped according to pre-HSCT calcidiol level: insufficient (<50 nm/L, n = 38) and sufficient (≥50 nm/L, n = 85). Older children who underwent transplants from January through June and children of Middle Eastern or African origin were more commonly found in the insufficient group. Acute grades II to IV graft-versus-host disease occurred more frequently in the vitamin D sufficient group (47% versus 30%, P = .05), whereas no difference was demonstrated for chronic graft-versus-host disease. The neutrophil granulocytes rose significantly faster in the vitamin D sufficient group. No difference in lymphocyte counts, immunoglobulin levels, or infectious disease burden during the first year post-HSCT were observed. Among children with malignancies, overall survival was significantly better in the sufficient group (87% versus 50%, P = .01). In addition, rejection (0% versus 11%, P = .06) and relapse (4% versus 33%, P = .03) rates were lower in patients with sufficient vitamin D levels. To conclude, vitamin D may have an important impact on the outcome of pediatric HSCT, particularly in patients with malignant disease. Further studies investigating whether vitamin D acts as an immunomodulator or is merely a surrogate marker of patient health or nutritional status are warranted.