Essential roles of growth hormone (GH) and insulin-like growth factor-I (IGF-I) in the liver

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play essential roles in growth in childhood, and continue to have important metabolic actions in adults. Adult growth hormone deficiency (AGHD) is characterized by increased visceral adiposity, abnormal lipid profiles, premature atherosclerosis, decreased quality of life, and increased mortality. Recently, case reports and several clinical studies suggest that GHD state in adults is associated with an increased prevalence of nonalcoholic fatty liver disease (NAFLD) and progression to nonalcoholic steatohepatitis (NASH) or liver cirrhosis. As a mechanistic insight, growing evidence has revealed that GH as well as IGF-I play essential roles in the liver. Further investigation is necessary to clarify the precise mechanisms by which GH and IGF-I exert their effects in the liver; however, it should be noted that NAFLD/NASH has emerged as an important comorbidity in AGHD.