25-OH Vitamin D Deficiency Following Pediatric Hematopoietic Stem Cell Transplant.
Authors: Duncan Christine , Apfelbaum Erin , Whitley Katherine , Margossian Steven P. , Lehmann Leslie E. 
Published: October 2019

Abstract
Abstract 1310
Children may be at increased risk for vitamin D deficiency following hematopoietic stem cell transplant (HSCT) due to lack of sun exposure, the recommended use of sunscreen, dietary insufficiency, malabsorption, and the use of corticosteroid and calcineurin inhibitors. We prospectively measured the 25-OH vitamin D and parathyroid hormone (PTH) levels of pediatric post-HSCT patients during three periods of four weeks in the spring and autumn of 2009 and in winter 2010. Patients aged 1 to 21 years were eligible for participation if they were transplanted at our institution and were within 2 years from stem cell infusion at the time of enrollment. Patients who were greater than 2 years from HSCT were eligible for participation if they were receiving immunosuppression for the treatment of chronic graft-versus-host disease (GVHD). A 25-OH vitamin D level greater than or equal to 30 ng/mL was considered normal, 20–29 ng/mL was considered insufficient, and less than 20 was considered deficient. Patients who had a vitamin D level in the deficient range received repletion with enteral ergocalciferol (50,000 IU once weekly for 6 weeks). A survey administered at the time of enrollment assessed potential risk factors for vitamin D deficiency. Between May 21, 2009 and February 23, 2010, a total of 67 patients had a 25-OH vitamin D level collected. The seasonal distribution of testing was 41.8% in the spring, 23.9% in the autumn, and 34.3% in the winter. The population was 62.7% male and had a median age at enrollment of 73 months. The median duration of time since HSCT was 69 days. The study population was 64.2% Caucasian, 13.4% Hispanic, 11.9% Asian, 7.5% African-American, and 3% mixed ethnicity. The majority of patients had an allogeneic HSCT (82.1%) from an unrelated donor (70.9%). The majority of patients took a calcineurin inhibitor (68.7%) and/or corticosteroids (38.8%) and 10.4% of the patients had active GVHD at enrollment. The prevalence of either vitamin D deficiency or insufficiency was 80.6% (95% confidence interval [CI] 69.1%-89.3%). The prevalence of vitamin D deficiency was 37.3% (CI, 25.8%-50%). The mean vitamin D level was highest in the autumn (28.0 ng/mL) in contrast to the mean values in the spring (21.0 ng/mL) and winter (21.4 ng/mL) (p=0.89). The 25 patients who had a vitamin D level in the deficient range were prescribed ergocalciferol and 22 patients completed six weeks of repletion. Three patients who were prescribed repletion died of relapsed leukemia prior to follow-up. The mean change in vitamin D level following supplementation was 18.8 (range 8–42, SD=11.3). Of the evaluable subjects 63.6% had a post-supplementation level in the normal range, 31.8% had a level in the insufficient range, and 4.5% remained deficient. The mean pre-supplementation level in patients with normal post-supplementation values was 15.1 ng/mL (range 8.3–19.3, SD=2.7) compared to 11.8 ng/mL (range 7–17.2, SD=4.0) in subjects who had abnormal post-supplementation levels (p=0.07). A PTH level at enrollment was available for 63 patients and the mean value was 77.5 pg/mL (range 7.2–450, SD=80.5). The correlation coefficient between the vitamin D and PTH levels was -0.0055 (p=0.96). In multivariate analysis of the age at enrollment, the use of sunscreen, daily sun exposure, the daily dietary intake of vitamin D containing foods, race, and calcineurin inhibitor or steroid use, only older age at enrollment was found to be a risk factor for vitamin D deficiency (p=0.004). Vitamin D insufficiency and deficiency are common following HSCT. Further investigation into potential risk factors and the appropriate supplementation for these patients is warranted.

Disclosures:
No relevant conflicts of interest to declare.