The initial evaluation of a patient with abnormal liver biochemical and function tests (LFTs) includes obtaining a history to identify potential risk factors for liver disease and performing a physical examination to look for clues to the etiology and for signs of chronic liver disease Subsequent testing is determined based on the information gathered from the history and physical examination as well as the pattern of LFT abnormalities The goal of emergency care is to determine if the patient is at risk for fulminant liver failure CLINICAL PEARLS AND PITFALLS A high index of suspicion is required to detect patients with viral hepatitis as the aminotransferase elevation may be very mild in children A history of immigration or adoption from high prevalence countries or family/personal history of high-risk exposures should prompt screening for hepatitis B virus (HBV) and hepatitis C virus (HCV), even if liver transaminases are only mildly elevated Hepatitis A virus (HAV) IgM suggests current or recent hepatitis A infection in the setting of HAV total antibody positivity Treatment is supportive HBV is 100-fold more infectious than human immunodeficiency virus (HIV) A positive anti-HBs (surface antibody) is present All HBsAgand HBcAb-positive patients merit confirmatory HBV DNA Infants at risk for vertical HCV transmission should not be tested until 18 months of age as maternal HCV antibody can circulate for over year If positive, confirm with HCV ribonucleic acid (RNA) quantitative polymerase chain reaction (PCR) and refer to Hepatology Current Evidence The existing alphabet of hepatitis viruses is now up to G, excluding F, with new variants awaiting discovery HAV, the cause of “infectious” or epidemic hepatitis, is an RNA virus transmitted by the fecal–oral route Hepatitis A is the second most common vaccine preventable infection in travelers and has an incubation period of 28 days (range 15 to 50) Peak infectivity occurs during