Diagnostic Strategies for Patients with Abnormal Liver Function Tests

Abnormalities in liver function tests (LFTs) may be caused not only by hepatic diseases but also by non-hepatic disorders, while normal values on LFTs do not exclude liver disease. Therefore, LFTs should be interpreted based on all information about the patient. Practically, classification of LFTs into hepatic synthetic function, hepatocellular injury, and cholestasis is important to interpret liver abnormalities and to identify the etiology of liver injury. Liver injuries can be divided into two categories, hepatocellular and cholestatic. These categories are helpful in diagnosing liver diseases and in understanding mechanisms of injury. The hepatocellular pattern is characterized primarily by increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, whereas the cholestatic pattern is characterized by increased alkaline phosphatase (ALP) and bilirubin levels. Identification of the pattern may narrow the possible causes of liver injury in a patient. Imaging tests, such as ultrasound, CT, and MRI, may be helpful in the final diagnosis of liver diseases.

Keywords: Albumin, aminotransferases, ammonia, bilirubin, cholestasis, hepatocellular injury, liver function tests, prothrombin time.