An elevation in aminotransferases may be of multiple etiologies and should be investigated. In this article, the different etiologies of increased aminotransferase blood levels are being reviewed, with a systematic approach to interpret transaminase alterations proposed. It is essential to establish whether aminotransferase blood levels are either acutely or chronically disturbed. A thorough assessment of personal and family past-medical history and exposure to toxics, medications, and dietary supplements should be obtained. Subsequently, given an acute perturbation, a baseline blood assessment for various viral etiologies must include HBs antigen, anti-HBc antibody, and IgM antibodies for hepatitis A, hepatitis E, EBV, CMV, HSV, VSV, and HIV. A liver Doppler ultrasound should be performed to exclude vascular etiologies.
Concerning chronic disturbances, alcohol consumption must be detailed, and metabolic syndrome sought using physical examination and biological parameters. In addition, one should screen for hepatitis B and C viral infection and for hemochromatosis (ferritin levels and transferrin saturation). In a second step, liver autoimmune and genetic diseases are to be looked for. A Doppler ultrasound of the liver should be performed in the event of chronic perturbation with the aim to assess the presence of steatosis and signs of cirrhosis. Any patient with severe acute hepatic impairment and chronic B or C viral infection or autoimmune, metabolic, and genetic disorders must be referred to a specialized centre.