Free 25-Hydroxyvitamin D Concentrations in Cystic Fibrosis

Am J Med Sci. 2015 Nov;350(5):374-9. doi: 10.1097/MAJ.0000000000000592.

Abstract

Background: Vitamin D deficiency is common in cystic fibrosis (CF), but there is no previous data on free 25-hydroxyvitamin D (25[OH]D) in CF or in relation to healthy individuals.

Methods: We assessed total serum 25(OH)D concentration by chemiluminescence and serum free 25(OH)D concentration by both direct measurement (ELISA) and calculation, using serum albumin and vitamin D binding protein (VDBP) levels in 80 subjects (28 healthy adults, 25 clinically stable adults and children with CF and 27 adults experiencing a CF exacerbation).

Results: Serum albumin and VDBP concentrations were lower in CF compared with healthy controls. Total serum 25(OH)D concentrations were positively correlated with both calculated and measured free 25(OH)D (P < 0.001 for both). Calculated and directly measured serum free 25(OH)D levels were positively correlated (P < 0.001).

Conclusions: Serum levels of directly measured free 25(OH)D positively correlated with total 25(OH)D, suggesting that achieving sufficient total serum 25(OH)D may result in adequate free 25(OH)D levels in CF.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Cystic Fibrosis* / blood
  • Cystic Fibrosis* / drug therapy
  • Cystic Fibrosis* / physiopathology
  • Dimensional Measurement Accuracy
  • Female
  • Georgia
  • Humans
  • Male
  • Outcome Assessment, Health Care
  • Patient Acuity
  • Serum Albumin / analysis*
  • Statistics as Topic
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D / therapeutic use*
  • Vitamin D-Binding Protein / blood*
  • Vitamins / therapeutic use

Substances

  • Serum Albumin
  • Vitamin D-Binding Protein
  • Vitamins
  • Vitamin D
  • 25-hydroxyvitamin D