// <![CDATA[ $('.header-date').hide();$('#titleAuthors').hide();$('#abstractHeader').hide(); // ]]> Rong Li1, *, Chao Guo2, *, Xinmou Wu4, Zhaoquan Huang1, 3 and Jian Chen1 1Key Laboratory of Tumor Immunology and Microenvironmental Regulation, Guilin Medical University, Guangxi, Guilin 541004, PR China 2Department of Pharmacy, Guigang City People’s Hospital, The Eighth Affiliated Hospital of Guangxi Medical University, Guigang, Guangxi 537100, PR China 3Department of Pathology, Affiliated Hospital of Guilin Medical University, Guangxi, Guilin 541004, PR China 4Department of Pharmacy, Guangxi Medical University, Guangxi, Nanning 530021, PR China *These authors share senior authorship Correspondence to: Jian Chen, email: chjian80726@163.com Zhaoquan Huang, email: hospital_huang@126.com Keywords: acetaminophen, liver impairment, biomarker, FGF21 Received: January 25, 2017 Accepted: May 06, 2017 Published: May 18, 2017 ABSTRACT Acetaminophen (APAP) is a common medication that induces hepatocellular damage in a time- or dose-dependent manner. Fibroblast growth factor 21 (FGF21) exerts a series of biological effects, including cellular repair. Compared to clinical diagnosis parameters, we aimed to evaluate whether FGF21 can serve as a sensitive biomarker for APAP-induced liver impairment. In the present study, we discussed comparable data from APAP-treated patients and parallelly established APAP-exposed mice for investigation. The resulting human serological data showed that APAP-treated patients have a visible reduction of FGF21 expression in undetected liver impairment of clinical diagnosis. In the animal study, APAP-exposed livers exhibited normal metabolic functions and liver functions, as revealed by biochemical test and histopathological examination. Endogenous FGF21 concentrations in APAP-treated mice were decreased in sera and liver cells. Moreover, comparable immunoassay data showed that hepatocellular FGF21 expression was reduced in a time-dependent manner. Taken together, these findings elucidate the involvement of abnormal FGF21 expression in early APAP-induced liver impairment. Interestingly, FGF21 may be a promising biomarker of APAP-exposed livers.