title: Treatment and prevention of vitamin D insufficiency in cystic fibrosis patients: comparative efficacy of ergocalciferol, cholecalciferol, and UV light.
abstract: 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 (D3), ergocalciferol (D2), and UV light in raising or maintaining 25(OH)D levels above 30 ng/ml.
  
  
  METHODS
  Thirty adult CF subjects with vitamin D insufficiency were randomized into one of three treatment arms: D3, D2, or UV light. Subjects randomized to D3 or D2 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 D3 and D2 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.
  
  
  CONCLUSIONS
  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 D3 or D2 treatment, the former being more efficacious. A confounding variable for this observation is the fact that the D3 and D2 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.
authors.affiliation: Division of Endocrinology, Diabetes, and Lipids, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Natasha B
authors.initials: NB
authors.lastname: Khazai
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Judd
authors.forename: Leo
authors.initials: L
authors.lastname: Jeng
authors.forename: Linda L
authors.initials: LL
authors.lastname: Wolfenden
authors.forename: Arlene
authors.initials: A
authors.lastname: Stecenko
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Ziegler
authors.forename: Vin
authors.initials: V
authors.lastname: Tangpricha