Although the liver can be affected in a wide range of disorders, the differential diagnosis of abnormal liver function tests can be substantially narrowed by a comprehensive history and physical examination and by the recognition of relatively distinct biochemical patterns of liver injury. Although referral to a specialist may be required for the performance of, for example, percutaneous liver biopsy and long-term management of chronic liver disease, a presumptive diagnosis can usually be made in the vast majority of patients who present to primary care physicians with abnormal liver function tests.