Review
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World J Gastroenterol. Jul 7, 2014; 20(25): 8102-8109
Published online Jul 7, 2014. doi: 10.3748/wjg.v20.i25.8102
Non-alcoholic fatty liver disease and thyroid dysfunction: A systematic review
Ahad Eshraghian, Alireza Hamidian Jahromi
Ahad Eshraghian, Department of Internal Medicine, Namazi hospital, Shiraz University of medical sciences, PO Box 71345-1744 Shiraz, Iran
Alireza Hamidian Jahromi, Department of Surgery, Louisiana State University Health Sciences Center, Shreveport, LA 70803, United States
Author contributions: Eshraghian A developed the concept of the study, performed the literature review, and participated in the critical appraisal, and writing of the article; Hamidian Jahromi A contributed in revising, language editing and final approval of the article.
Correspondence to: Ahad Eshraghian, MD, Department of Internal Medicine, Namazi hospital, Shiraz University of medical sciences, PO Box 71345-1744 Shiraz, Iran. eshraghiana@yahoo.com
Telephone: +98-711-6125600 Fax: +98-711-6276212
Received: November 19, 2013
Revised: March 31, 2014
Accepted: April 28, 2014
Published online: July 7, 2014
Abstract

Thyroid hormones are totally involved in the regulation of body weight, lipid metabolism, and insulin resistance. Therefore it is anticipated that thyroid hormones may have a role in the pathogenesis of non alcoholic fatty liver disease (NAFLD) and non alcoholic steatohepatitis (NASH). In this study, we reviewed the current literature on the association between thyroid dysfunction and NAFLD/NASH. A search for English language medical literature reporting an association between thyroid dysfunction and NAFLD/NASH in humans was conducted across PubMed, ISI Web of Science, and Scopus in August, 2013. Out of 140 studies initially identified through the search, 11 relevant articles were included in the final review. Thyroid dysfunctions in the form of overt or subclinical hypothyroidism are prevalent among patients with NAFLD/NASH. Hypothyroidism appears to be an independent risk factor for NAFLD/NASH in some studies; however, other newly published studies failed to find such an association. The results of the studies on the role of thyroid abnormalities in NAFLD/NASH are inconsistent, and further research is recommended to determine the relationship between hypothyroidism and NAFLD/NASH and the underlying mechanisms.

Keywords: Non alcoholic fatty liver disease, Thyroid dysfunction, Hypothyroidism, Non alcoholic steatohepatitis, Risk factor, Pathophysiology

Core tip: Thyroid hormones help regulate of body weight, lipid metabolism, and insulin resistance. Therefore, thyroid hormones may have a role in the pathogenesis of non alcoholic fatty liver disease (NAFLD) and non alcoholic steatohepatitis (NASH). Following a systematic review of human studies in the English language medical literature, eleven articles were found to address this relationship. Hypothyroidism appears to be an independent risk factor for NAFLD/NASH in some studies; however, other studies failed to find such an association. As the results of these studies are not consistent, further research is recommended to determine the relationship hypothyroidism and NAFLD/NASH and the underlying mechanisms.