399 - Single High-Dose Oral Vitamin D3 (Stoss Dose) in Lieu of Daily Dosing is Reliably Effective for Treatment of Vitamin D Insufficiency/Deficiency in Pediatric Hematopoetic Stem Cell Transplant (HSCT) Recipients

Abstract

Background: It is estimated as many as 70% of children in the United States have deficient or insufficient vitamin D levels. Pediatric HSCT recipients are particularly at high risk for deficiency due to sun avoidance and sunscreen use, malabsorption, and increased catabolism due to steroid and/or calcineurin inhibitor use. It has also been postulated that maintaining adequate vitamin D levels can impact outcomes such as engraftment, graft-versus-host disease, and rejection. Given their complex medication regimens, addition of a daily vitamin D maintenance dose may lead to non-adherence and an inability to achieve adequate levels. Methods: This was a retrospective single-center analysis of pediatric HSCT recipients that received single high-dose oral vitamin D therapy beginning in May 2014. Vitamin D deficiency was defined as a 25-hydroxyvitamin D (25(OH) D) level below 20 ng/mL and insufficiency as a level of 21-29 ng/mL. The patients received doses according to dosing guidelines established in the pediatric Cystic Fibrosis population at this institution, adapted from the study by Shepherd et al in 2013. (Table 1)Table 125-OH Vit D Level (ng/mL)<3 yrs3-12 yrs>12 yrs≤ 10200,000 units400,000 units600,000 units10-20150,000 units350,000 units500,000 units20-30100,000 units200,000 units300,000 units Open table in a new tab Results: There were 14 patients identified as having received vitamin D stoss therapy and 20 doses administered. All patients evaluated had received allogeneic HSCT. In patients for whom follow-up levels were available (n = 17), an average increase in 25(OH) D level of 21 ng/mL was observed. In patients that received multiple doses, (n = 3) there was an average of 90.6 days between administrations. Two patients in the study group had follow-up levels decrease following stoss therapy, likely attributed to critical illness at the time of administration. No toxicities associated with high-dose vitamin D administration were observed. Conclusion: Single high-dose oral vitamin D therapy is an effective method for restoring and maintaining adequate vitamin D levels in this patient population. This approach reduces the need for the addition of a daily maintenance medication and allows for controlled, periodic dosing and monitoring.