title: Classical and emerging roles of vitamin D in hepatitis C virus infection.
abstract: According to the Institute of Medicine, the risk of clinically significant vitamin D deficiency increases at 25-hydroxyvitamin D levels below 20 ng/mL. By this standard, most cirrhotic hepatitis C virus- (HCV-) positive patients and many noncirrhotic patients are vitamin D-deficient. The high prevalence of vitamin D deficiency among HCV patients is a cause for concern for several specific reasons. Classic studies established the importance of vitamin D and calcium in maintaining bone. Vitamin D's beneficial effects on bone are likely to be vital for HCV-infected patients because these individuals have a high prevalence of low bone mineral density. Many pharmaceutical agents reduce bone density and exposure to these drugs may increase bone disease in HCV-positive patients. Bone loss occurs following liver transplantation and bone density is often low in patients with HIV/HCV co-infection who are on combination antiretroviral therapy. Some evidence suggests that ribavirin reduces bone density, underscoring the special need to monitor vitamin D in patients receiving HCV treatment and to prescribe supplements, as appropriate. In addition to its role in calcium metabolism, vitamin D is also an immune modulator that reduces inflammation while enhancing protective immune responses. Higher vitamin D levels are associated with less liver fibrosis and less inflammation in HCV patients. Recent studies show that low vitamin D levels are associated with treatment failure among HCV-infected patients receiving pegylated-interferon and ribavirin. If confirmed, these findings will provide an additional reason to ensure adequate levels of vitamin D. Information about how to monitor vitamin D status and how to use vitamin D supplements most effectively in HCV-infected patients is provided.
authors.affiliation: Division of Gastroenterology, University of California-San Diego, CA, USA.
authors.forename: Julio A
authors.initials: JA
authors.lastname: Gutierrez
authors.forename: Neil
authors.initials: N
authors.lastname: Parikh
authors.forename: Andrea D
authors.initials: AD
authors.lastname: Branch
mesh_terms: D000998:Antiviral Agents / Q000009:adverse effects; D006528:Carcinoma, Hepatocellular / Q000150:complications / Q000378:metabolism; D016174:Hepacivirus / Q000276:immunology; D019698:Hepatitis C, Chronic / Q000150:complications / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007372:Interferons / Q000009:adverse effects; D008113:Liver Neoplasms / Q000150:complications / Q000378:metabolism; D010024:Osteoporosis / Q000150:complications / Q000378:metabolism; D012254:Ribavirin / Q000009:adverse effects; D014807:Vitamin D / Q000494:pharmacology* / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000150:complications / Q000276:immunology / Q000378:metabolism*; D014815:Vitamins / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000998:Antiviral Agents; D014815:Vitamins; D014807:Vitamin D; D012254:Ribavirin; D007372:Interferons