title: Vitamin D in chronic liver disease.
abstract: Chronic liver disease (CLD) and several related extrahepatic manifestations such as hepatic osteodystrophy are associated with deficiency of vitamin D, which has therefore been suggested as therapeutic target. Vitamin D undergoes hepatic 25-hydroxylation, rendering the liver critical to the metabolic activation of this vitamin. Vitamin D deficiency is highly prevalent in CLD patients, and vitamin D levels are inversely related to the severity of CLD. Declining levels of carrier proteins such as albumin and vitamin D-binding protein might also be critical in CLD. Intervention studies report improvements of CLD following supplementation, and benefits to health outcomes in particular with respect to hepatitis C virus infection have recently been documented.
  
  
  BACKGROUND
  We discuss vitamin D sources, functions and metabolism with a focus on the inherent complications of analytical measurements, such as the interference of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D C-3 epimers. Global discrepancies in the definition of optimal serum 25-hydroxyvitamin D levels are covered, and the prevalence of vitamin D deficiency in CLD is reviewed. We also address the functional mechanisms underlying this deficiency, and refer to associations between genetic variation in vitamin D metabolism and CLD. Lastly, we consider the health implications of a vitamin D deficiency in CLD and consider therapeutic options.
  
  
  CONCLUSIONS
  Herein, we focus on the epidemiological and functional relationships between vitamin D deficiency and CLD, followed by a discussion of the potential implications for therapeutic interventions.
authors: Department of Medicine II, Saarland University Medical Center, Homburg, Germany. caroline.stokes@uks.eu
authors: Caroline S
authors: CS
authors: Stokes
authors: Dietrich A
authors: DA
authors: Volmer
authors: Frank
authors: F
authors: Grünhage
authors: Frank
authors: F
authors: Lammert
mesh_terms: D000367:Age Factors; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008107:Liver Diseases / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D053858:Metabolic Networks and Pathways; D015394:Molecular Structure; D015995:Prevalence; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000150:complications* / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D