Treatment and Prevention of Vitamin D Insufficiency in Cystic Fibrosis Patients: Comparative Efficacy of Ergocalciferol, Cholecalciferol, and UV Light

Background: The optimal treatment for correcting or preventing vitamin D insufficiency in cystic fibrosis (CF) patients has not been established. Objective: The aim of the study was to assess the relative efficacy of three modes of vitamin D therapy: cholecalciferol (D-3), ergocalciferol (D-2), and UV light in raising or maintaining 25(OH)D levels above 30 ng/ml. Design: Thirty adult CF subjects with vitamin D insufficiency were randomized into one of three treatment arms: D-3, D-2, or UV light. Subjects randomized to D-3 or D-2 ingested 50,000 IU of vitamin D weekly, and those randomized to UV exposed their skin to UV light from a lamp five times a week. Serum was collected for 25(OH)D and PTH at baseline and at 12 wk. Results: Treatment with D-3 and D-2 raised 25(OH)D levels significantly, from a mean of 21.2 +/- 10.18 to 47.1 +/- 20.5 ng/ml (P < 0.001) and 24.4 +/- 10.3 to 32.7 +/- 9.7 ng/ml (P = 0.01), with 100% and 60% reaching 25(OH)D levels above 30 ng/ml, respectively. Treatment with UV did not raise 25(OH)D levels significantly; however, only 55% of subjects were adherent with UV therapy. Conclusion: This study demonstrates that CF subjects are able to achieve or maintain optimal vitamin D status (>30 ng/ml) with two oral regimens of either D-3 or D-2 treatment, the former being more efficacious. A confounding variable for this observation is the fact that the D-3 and D-2 capsules contained different carriers, powder-based vs. oil-based, respectively. UV therapy did not alter vitamin D status, possibly due to poor adherence to UV therapy. (J Clin Endocrinol Metab 94: 2037-2043, 2009)