Free 25-Hydroxyvitamin D Concentrations in Cystic Fibrosis

• Type of Material: Article
• Authors: Moon Jeong Lee, Emory University; Malcolm D. Kearns, Emory University; Ellen M. Smith, Emory University; Li Hao, Emory University; Thomas Ziegler, Emory University; Jessica Alvarez, Emory University; Vin Tangpricha, Emory University
• Language: English
• Date: 2015-11-01
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2015 by the Southern Society for Clinical Investigation.
• Final Published Version (URL): http://dx.doi.org/10.1097/MAJ.0000000000000592
• Title of Journal or Parent Work: American Journal of the Medical Sciences
• ISSN: 0002-9629
• Volume: 350
• Issue: 5
• Start Page: 374
• End Page: 379
• Grant/Funding Information: This work was supported in part by National Institutes of Health grants T32 DK007734 (ES), K24 DK096574 (TRZ), T32 DK007298-32S1 and K01 DK102851 (JAA), UL1 TR000454 (Atlanta Clinical and Translational Science Institute), and McCart145R0 (Biobank of CF specimens).
• Keywords: Science & Technology; SERUM; POPULATION; 1,25-DIHYDROXYVITAMIN-D; General & Internal Medicine; Vitamin D; DENSITY; Vitamin D binding protein; Cystic fibrosis; AMERICANS; Life Sciences & Biomedicine; Endocrinology; Free 25-hydroxyvitamin D
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, Nutrition

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.