Introduction
Allogeneic hematopoietic stem cell transplant
Allogeneic hematopoietic stem cell transplant (aHSCT) patients are well known to be at high risk of vitamin D (vit D) deficiency both pre- and post-transplant [In addition to the essential role of vit D in maintaining bone health, vit D also exerts potent immunomodulatory effects [Similar to a report in the pediatric literature [100,000 IU vit D