A randomized controlled trial of vitamin D replacement strategies in pediatric CF patients

BackgroundVitamin D insufficiency is common in children with cystic fibrosis (CF), yet data are sparse regarding the most effective form of vitamin D supplementation. The aim of this study was to compare two different vitamin D replacement regimens.MethodsWe conducted a randomized controlled trial comparing 50,000 IU of ergocalciferol (vitamin D2) twice weekly for 8 weeks versus 50,000 IU of cholecalciferol (vitamin D3) weekly in patients with CF, pancreatic insufficiency, age 6-21 years and a 25(OH)D < 30 ng/mL. The primary outcome was change in serum 25(OH)D concentration. For secondary analyses, we examined changes in IgG, IgE and CRP in patients who normalized their vitamin D levels.ResultsA total of 47 patients completed the trial. The mean pre-treatment 25(OH)D concentration was 23.1 (SD 4.7) ng/mL. The overall mean increase in 25(OH)D was 11.1 (11.9) ng/mL and 31/47 (66%) achieved a 25(OH)D concentration ≥ 30 ng/mL; of the 26 participants who received D2, 18 (69%) achieved sufficiency while 13/21 (62%) participants treated with D3 achieved sufficiency. There was no difference between groups in change of 25(OH)D (p = 0.65). Similarly, there was no difference in the number of patients to achieve vitamin D sufficiency between treatments (p = 0.6).ConclusionsErgocalciferol administered as 50,000 IU twice weekly is as effective as cholecalciferol 50,000 IU weekly for 8 weeks in pediatric patients with CF and vitamin D insufficiency. Only 66% of the patients studied achieved the desired 25(OH)D concentration.