There are several laboratory tests that may be used in cases of known or suspected hepatitis. These tests may be used for various reasons and may fall into one or more of these categories:
- General chemistry tests used to detect liver inflammation and/or damage
- Screening tests used to detect Viral Hepatitis; for example, screening for exposure to hepatitis B or hepatitis C may be done because of increased risk of the disease (use of illegal drugs, multiple sex partners) or at the time of blood donation.
- Tests used to help diagnose the underlying cause
- Follow-up tests used to monitor progression of hepatitis and/or help guide treatment
Acute hepatitis is often suspected and testing done because of the appearance of symptoms such as fever, loss of appetite, and nausea, often accompanied by dark urine, pale stools, and yellow discoloration of the skin and the whites of the eyes (jaundice or icterus).
Chronic hepatitis is more commonly detected as a result of abnormal routine test results. In a patient who is having no, few, or vague symptoms, hepatitis may be first discovered during routine testing such as a Comprehensive Metabolic Panel (CMP).
The CMP is a group of tests frequently ordered as part of a yearly physical. It includes several tests from the liver panel. These tests may be the first indication of liver inflammation or injury. While these tests may help to detect hepatitis, they do not determine the underlying cause. Additional testing may be necessary to pinpoint the cause and to help direct treatment.
In addition to the CMP, other general tests may be used both to detect liver injury and to give an indication of how severe it may be. Some of these are listed below:
- Alanine aminotransferase (ALT) - an enzyme found mainly in the liver; the best test for detecting hepatitis
- Aspartate aminotransferase (AST) – an enzyme found in the liver and a few other places, particularly the heart and other muscles
- Alkaline phosphatase (ALP) – an enzyme related to the bile ducts; often increased when they are blocked, but may also be increased with bone disorders
- Gamma-glutamyl transpeptidase (GGT) - an enzyme found in the liver that is very sensitive to changes in liver function; helps to differentiate between the causes of an elevated ALP; if GGT is increased, then the elevated ALP is due to liver, not bone disease.
- Bilirubin - a waste product made from the breakdown of old blood cells; it is a yellow compound that causes jaundice and dark urine when present in increased amounts.
- Albumin - measures the main protein made by the liver and tells how well the liver is making this protein
- Total Protein - measures albumin and all other proteins in blood, including antibodies made to help fight off infections
- Prothrombin time (PT). This test may be ordered in a person with hepatitis or suspected hepatitis. Proteins used in the formation of a blood clot (coagulation factors) are mostly produced by the liver, and prolonged PT may indicate the severity of liver damage.
- A liver biopsy, in which a needle is inserted into the liver to withdraw a small amount of cells that are examined under a microscope by a pathologist, is the most definitive way to diagnose the disease. Since this is an invasive procedure, it is used primarily when other tests are inconclusive or to determine how much damage to the liver has occurred.
For information on laboratory tests used for specific types of hepatitis, click on the links found in the Table on the Overview page.
Imaging tests such as ultrasound and specialized X-rays may be used to evaluate the liver, detect hepatitis, help make a diagnosis, and help determine a cause of livery injury.