title: Failure of high-dose ergocalciferol to correct vitamin D deficiency in adults with cystic fibrosis.
abstract: BACKGROUND
  Treatment guidelines for vitamin D monitoring and supplementation in cystic fibrosis (CF) have recently been developed and published by a consensus committee, but have not been prospectively tested.
  
  
  OBJECTIVE
  To use these guidelines to determine the percentage of adults with CF requiring vitamin D repletion therapy and to evaluate the effectiveness of the currently recommended high-dose oral ergocalciferol repletion protocol.
  
  
  METHODS
  Prospective study of clinical outcomes after therapy with the recommended vitamin D repletion algorithm.
  
  
  RESULTS
  Of 134 adults with CF, 109 (81.3%) were found to have 25-hydroxyvitamin D (25-OHD) levels below the recommended 30 ng/ml. Sixty-six of these adults completed the recommended course of 400,000 IU of oral ergocalciferol over 2 months, and only five (8%) responded with correction of their serum 25-OHD to the goal of 30 ng/ml or greater (mean change, +0.3 ng/ml; from 18.8 to 19.1 ng/ml). In the 33 adults with CF who also completed the recommended second course of 800,000 IU of ergocalciferol over 2 months, none demonstrated correction of their deficiency (mean change, -1.2 ng/ml).
  
  
  CONCLUSIONS
  The results of this study demonstrate that a majority of adults with CF have serum 25-OHD levels below 30 ng/ml, and the currently recommended ergocalciferol repletion regimen often does not fully correct vitamin D deficiency and may need to be revised to include even higher dosing of ergocalciferol. Further work is needed to establish the ideal 25-OHD level for maximizing calcium absorption and bone health in CF.
authors.affiliation: Johns Hopkins Adult CF Program, 1830 East Monument Street, 5th floor, Baltimore, MD 21205, USA. mboyle@jhmi.edu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Boyle
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Noschese
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Watts
authors.forename: Marsha E
authors.initials: ME
authors.lastname: Davis
authors.forename: Shane E
authors.initials: SE
authors.lastname: Stenner
authors.forename: Noah
authors.initials: N
authors.lastname: Lechtzin
mesh_terms: D000328:Adult; D003550:Cystic Fibrosis / Q000150:complications*; D004305:Dose-Response Relationship, Drug; D004872:Ergocalciferols / Q000008:administration & dosage* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019233:Retreatment; D012621:Seasons; D017211:Treatment Failure; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000188:drug therapy* / Q000209:etiology*
chemical_list: D004872:Ergocalciferols; D014807:Vitamin D; C104450:25-hydroxyvitamin D