Liver Blood Tests (cont.)
Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- What are the basic functions of the liver?
- What are common liver blood tests?
- What are the aminotransferases?
- Normally, where are the aminotransferases?
- What are normal levels of AST and ALT?
- What do high (elevated) liver tests (AST and ALT) mean?
- Do AST and ALT test results indicate liver function?
- Which blood tests are done to detect liver function?
- What are some common reasons for abnormal liver tests?
- What medications can cause increased liver enzyme tests (abnormal aminotransferase levels)?
- What conditions can cause very high aminotransferase levels?
- What are some of the less common causes of elevated liver blood tests?
- How are healthy people evaluated for mild to moderate rises in aminotransferase levels?
- How about monitoring liver blood tests?
- What about the other liver enzymes?
- Hepatitis Slideshow Pictures
- Take the Alcohol Quiz
- Alcohol Abuse Slideshow Pictures
What conditions can cause very high aminotransferase levels?
AST and ALT serum levels in some liver conditions can range anywhere from ten times the upper limits of normal to thousands of units/liter The highest levels of AST and ALT are found with disorders that cause rapid death of numerous liver cells (extensive hepatic necrosis). Although this degree of liver enzymes elevation is not common, it can occur in such conditions as:
- Acute viral hepatitis A or B
- Profound liver damage inflicted by toxins as from an overdose of acetaminophen (brand-name Tylenol) or mushroom poisoning
- Prolonged collapse of the circulatory system (shock) when the liver is deprived of fresh blood providing oxygen and nutrients
Also, very high AST and ALT levels can be a result of severe muscle diseases.
What are some of the less common causes of elevated liver blood tests?
Less common causes of abnormal liver enzymes in the United States include hemachromatosis (iron overload), Wilson's disease, alpha-1-antitrypsin deficiency, celiac disease, Crohn's disease, ulcerative colitis, and autoimmune hepatitis. Though not as common as hepatitis C, hepatitis B can cause chronic liver disease with persistently abnormal liver enzymes.
- Hemachromatosis is a genetic (inherited) disorder in which there is excessive absorption of dietary iron leading to accumulation of iron in the liver with resultant inflammation and scarring of the liver. If undiagnosed or untreated, hemachromatosis can progress to cirrhosis and liver failure.
- Wilson's disease is an inherited disorder with excessive accumulation of copper in diverse tissues including the liver and the brain. Excess copper in the liver can lead to chronic liver inflammation, while copper in the brain can cause psychiatric and motor disturbances.
- Alpha-1-antitrypsin deficiency is an inherited disorder in which the lack of a glycoprotein (carbohydrate-protein complex) called alpha-1-antitrypsin lead to chronic lung disease (emphysema) and chronic liver disease.
- Autoimmune hepatitis results from liver injury brought about by the body's own antibodies and defense systems attacking the liver.
- Celiac disease (celiac sprue) is a disease of the small intestine where a person has an allergy to gluten and develops gas, bloating, diarrhea, and in advanced cases malnutrition. Patients' with celiac dksease can also develop mildly abnormal ALT and AST levels.
- Crohn's disease and ulcerative colitis are diseases with chronic inflammation of the intestines (collectively referred to as inflammatory bowel diseases). In these individuals inflammation of the liver (hepatitis) or bile ducts (primary sclerosing cholangitis) also can occur, causing abnormal liver tests.
- Viral infections other than common hepatitis viruses (A, B, C) can sometimes cause elevation of liver enzymes as they can result in generalized body infection and liver inflammation.
- Non-viral infections of the liver are rare, but they can cause liver damage. Bacterial and amebic hepatic (liver) abscesses typically present as focal infection and inflammation of the liver as opposed to viral hepatitis where generalized liver inflammation occurs. Liver enzyme elevation is usually seen in the setting of these infections.
- Rarely, abnormal liver enzymes can be a sign of liver cancer. Cancer arising from liver cells is called hepatocellular carcinoma or hepatoma. Cancers spreading to the liver from other organs (such as colon, pancreas, stomach, and others) are called metastatic malignancies (to the liver).
- Liver hemangiomas (masses of abnormal and atypical blood vessels within the liver) are the most common tumors in the liver. Hepatic hemangiomas are benign and in general do not cause elevation of liver tests.
- Another rare condition that causes elevation of liver tests is called the Budd-Chiari Syndrome. In this condition, obstruction of blood flow in the liver by a blood clot can damage the liver by limiting blood flow leading to injury of liver cells. As a result of this insult, liver enzymes may rise indicating hepatic inflammation.
- Glycogen storage disorders are genetic conditions seen in pediatric population (detected at birth in severe types or later in childhood in less severe types). They impair the ability of liver to store and metabolize glycogen, a complex sugar necessary for production of nutrients and energy in the body. Glycogen storage disorders cause varying degrees of liver enzyme abnormalities.
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