The Prevalence of 25-Hydroxyvitamin D Deficiency in Post-HSCT Pediatric Patients.

Children undergoing HSCT are at risk for vitamin D deficiency due to lack of sun exposure, the recommended use of sunscreen, dietary insufficiency, and the effects of medications such as glucocorticoids and calcineurin inhibitors. We assessed the prevalence of 25-hydroxyvitamin D (25-OH vitamin D) deficiency in pediatric post-HSCT patients in an outpatient oncology clinic during 4 weeks in May 2008. Patients found to have low 25-OH vitamin D levels were referred for dietary counseling and given supplementation or repletion as needed. 25-OH vitamin D and parathyroid hormone (PTH) levels were measured in 62 (88.6%) of 70 eligible patients. 83.8% of patients had a 25-OH vitamin D level less than the institutional lower limit of normal, 30 ng/mL. 29% of patients were 25-OH vitamin D insufficient with levels 20–29 ng/mL (range of 20–29). 54.8% of patients were 25-OH vitamin D deficient with levels <20 ng/mL (range 5–19). The prevalence of insufficiency and deficiency was similar between male (87.8%; 57.6%) and female patients (57.6%; 55.2%).The mean duration of days following transplant was 532.6 days (median 251.5 days). The mean age at transplant was 3.7 years (median 3.5 years). 47% of patients were female. 75.8% were Caucasian. 90.3% received allogeneic transplants. The underlying diseases were as follows: ALL (27.4%), AML/MDS (24.2%), bone marrow failure (11.3%), nonmalignant hematologic diagnosis (8.1%), solid tumor (8.1%), immunodeficiency (6.5%), lymphoma (6.5%), and other diagnoses (8.1%). 8 patients regularly took either an over-the-counter multivitamin or vitamin D supplement and all 8 patients had 25-OH levels less than 30 ng/mL. There was a negative inverse correlation of (r= −0.3, p=0.029) between PTH and 25-OH vitamin D. There were no significant associations between 25-OH vitamin D level and any of the following: corticosteroid or calcineurin inhibitor use in the preceding year, time from transplant, age at transplant, current age, or graft-versus-host disease. 25-OH vitamin D insufficiency and deficiency are common following pediatric HSCT. We recommend vitamin D screening for all post-HSCT pediatric patients. Further investigation is needed to identify potential risk factors for vitamin D deficiency and the long-term effects of deficiency on bone health and development.