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?
- What 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
How are healthy people evaluated for mild to moderate rises in aminotransferase levels?
Evaluation of healthy individuals with abnormal liver enzymes needs to be individualized. A doctor may ask for the patient's blood test data from old records for comparison. If no old records are available, the doctor may repeat blood tests in weeks to months to see whether these abnormalities persist.
In the meantime, along with a physical examination, by performing thorough medical history the doctor will search for potential infectious and non-infectious causes and risk factors for liver disease such as:
- Alcohol use
- Sexual exposures
- History of blood transfusions
- History of injectable drug use
- Occupational exposure to blood products
- Family history of liver disease (for the possibility of inherited diseases such as hemachromatosis, Wilson's disease, or alpha-1-antitrypsin deficiency).
A complete list of routine medications including over-the-counter medications will be reviewed.
Signs and symptoms of liver disease may or may not be present in individuals with mild increase in liver enzymes. Signs of liver damage can include jaundice, easy bruising, ascites (distention of abdomen as result of retained fluid), enlarged spleen (splenomegaly), and confusion. Symptoms liver disease are non-specific and numerous. Some of the more common liver disease symptoms may include fatigue, itching, yellow skin, poor appetite, and abdominal discomfort.
The pattern of liver enzyme abnormalities can sometimes provide useful clues as to the cause of the liver condition. For example, in a majority of people with alcoholic liver disease, liver enzyme levels are not as high as the levels reached in acute viral hepatitis. In alcoholic liver disease, frequently AST tends to be higher (usually under 300 units/liter) than ALT (usually under 100 units/ liter).
If alcohol or medication is responsible for the abnormal liver enzyme tests, stopping alcohol or the culprit medication (under a health care professional's supervision only) should bring the enzyme levels to normal or near normal levels in weeks to months. If obesity is suspected as the cause of fatty liver disease, weight reduction of about 5% to 10% should also bring the AST and ALT liver blood tests to normal or near normal levels in some individuals.
If abnormal liver enzymes persist despite abstinence from alcohol, weight reduction, and stopping certain suspected drugs, other tests can be performed to help diagnose other possible treatable liver diseases. The blood can be tested for the presence of hepatitis B and C viruses and their related antibodies. Blood levels of iron, iron saturation, and ferritin (another measurement of the amount of iron stored in the body) are usually elevated in individuals with hemachromatosis. Blood levels of a substance called ceruloplasmin are usually decreased in people with Wilson's disease. Blood levels of certain antibodies (anti- nuclear antibody or ANA, anti-smooth muscle antibody, and anti-liver and kidney microsomal antibody) are elevated in individuals with autoimmune hepatitis.
Liver ultrasound and CT scan of the abdomen are sometimes used to exclude tumors in the liver or other conditions such as gallstones or tumors obstructing the ducts that drain the liver. These tests also can provide important visual information about the liver such as size, contour, scarring, and anatomically important data. A CT liver scan is very useful to detect traumatic injuries to the liver.
Liver biopsy can occasionally assist in determining the cause of liver disease. In this procedure a needle is inserted through the skin over the right upper abdomen to obtain a thin strand of liver tissue for examination under a microscope. Liver biopsy is oftentimes performed after ultrasound study has located the liver. Not everybody with abnormal liver enzymes needs a liver biopsy. The doctor will usually recommend this procedure if:
- The information obtained from the liver biopsy will likely be helpful in planning treatment
- The doctor needs to know the extent and severity of liver inflammation/damage
- Effectiveness of a certain treatment requires close monitoring at the tissue level
- No obvious cause of elevated liver tests has been found despite thorough investigation
Liver biopsy is most useful in confirming a diagnosis of a potentially treatable condition including chronic hepatitis B and C, hemachromatosis, Wilson's disease, autoimmune hepatitis, and alpha-1-antitrypsin deficiency.
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