Approach to the patient with abnormal liver tests.

Patients with abnormal liver blood tests are frequently encountered by primary care practitioners. An understanding of the cellular implications of these abnormalities is helpful in determining the etiology of liver injury. Elevated serum aminotransferases suggest injury of hepatocytes. Elevations in alkaline phosphatase suggest injury to any part of the biliary tree. Neither of these enzymes measures liver function. Serum bilirubin and albumin levels, as well as prothrombin time, do measure function and can be used in conjunction with the physical examination and the specific etiology of the patient's disorder to determine a patient's prognosis. Many diverse disorders result in similar biochemical patterns of liver injury. The history, physical examination, and use of specific disease markers (hepatitis serology, autoimmune markers, and so forth) help to narrow the differential diagnosis. The definitive diagnosis of all liver diseases usually rests on histology: the liver biopsy is the gold standard. With the advent of treatments for liver disease, identifying and accurately diagnosing patients with liver disorders will result in improved quality of life and survival.