Liver tests indicate overall liver function and may point to liver disease and damage. Tests checking liver function include liver enzymes alanine transaminase (ALT) and aspartate transaminase (AST), albumin, ammonia, bilirubin, and prothrombin time. Combined, these tests point to disease and damage of the liver. When these liver levels increase, further testing may be required to find the cause of disease. Liver damage occurs due to a number of conditions.
Hepatitis
Hepatitis refers to inflammation of the liver tissue. Viral hepatitis includes types A, B, C, D, E, F, and G. According to Donna Ignatavicius and Linda Workman, authors of "Medical Surgical Nursing," acute viral hepatitis often causes some liver damage. Hepatitis B and C often become chronic disease and cause liver failure or liver cancer. With chronic hepatitis, liver levels often become elevated due to the extensive damage caused by the disease.
Medications and Alcohol
Chronic, heavy use of alcohol causes a condition known as cirrhosis. Alcohol damages liver tissue, leaving behind tough scar tissue that no longer performs the functions of a healthy liver. The American Academy of Family Physicians also lists several medications that elevate liver levels. These medications include acetaminophen, amiodorone, augmentin, carbamazine, trazadone, sulfanomides, phenytoin, fluconazole, glyburide, heparin, isoniazid, ketoconazole, labetalol, nitrofurantoin, and nonsteriodal anti-inflammatory medications. Herbs such as kava, senna, and vitamin A also cause elevations in liver levels.
Fatty Liver Disease
Fatty liver disease--also called steatosis--caused by a high-fat diet also causes inflammation of the liver. Long-term intake of fatty foods over time causes damage similar to damage from hepatitis or heavy alcohol consumption. Dr. David E. Johnson of the University School of New Mexico School of Medicine reports that liver enzymes ALT and AST often elevate in obese persons, and these levels often decrease with weight loss.
Other Causes
Other causes of elevated liver tests reported by the American Academy of Family Physicians include hemocromatosis, Wilson disease, alpha1-antitrypsin deficiency, hyperthyroidism, celiac disease, and exercise that causes muscle damage. Ignatavicius and Workman also report that inflammation and damage sometimes occurs after illness with the Epstein-Barr virus, herpes, chicken pox and cytomegalovirus.
References
- American Academy of Family Physicians: Special Considerations in Interpreting Liver Function Tests
- American Academy of Family Physicians: Mildly Elevated Liver Transaminase Levels in the Asymptomatic Patient
- "Medical Surgical Nursing"; Ignatavicius, D. MSN, Workman, L. PhD.; 2002
