Abstract
Little is known about serum vitamin D levels following hematopoietic cell transplantation (HCT). Patients are instructed to avoid sun exposure because of an increased risk of skin cancers. Altered gastrointestinal absorptive capacity as a result of GVHD, bile acid or pancreatic enzyme insufficiency or bacterial overgrowth may lead to difficulty in absorbing the fat-soluble vitamin D. This study was undertaken to determine the prevalence of serum 25-hydroxyvitamin D (25(OH)D) deficiency, and factors associated with 25(OH)D deficiency, among children and adults who were at least 1 year following HCT. A total of 95 participants (54 males and 41 females) completed a questionnaire on usual diet and lifestyle, and provided a blood sample for 25(OH)D determinations between November 2008 and July 2009. The majority of participants had serum 25(OH)D levels ≥75 nmol/L (n=62, 65%), 23 had insufficient levels (50-75 nmol/L) and 10 participants were deficient (<50 nmol/L). The majority of participants reported regular use of vitamin D supplements (n=58, 61%). Prednisone use was significantly inversely associated with serum 25(OH)D concentrations. Total vitamin D intake was the strongest single predictor of 25(OH)D concentrations. These findings suggest that 400-600 IU vitamin D per day appears to be required to achieve optimal serum 25(OH)D concentrations following HCT.