The Test Sample
What is being tested?
Hepatitis is an inflammation and enlargement of the liver. One of the most common causes of acute hepatitis is infection with a hepatitis virus, usually hepatitis A, hepatitis B or hepatitis C. An acute viral hepatitis panel is a group of blood tests often performed together to help diagnose viral hepatitis. Some of the tests detect antibodies produced by the immune system in response to the infection and one detects proteins (antigens) that indicate the presence of the virus.
A hepatitis panel typically includes:
- Hepatitis A antibody, IgM
- Hepatitis B core antibody, IgM
- Hepatitis B surface Ag
- Hepatitis C antibody
If acute symptoms are suspected to be caused by one of the hepatitis viruses or if someone is at an increased risk of being infected or has been exposed, then a hepatitis panel can help determine if the person has been infected and which virus is present.
Hepatitis A virus (HAV) is highly contagious and is usually contracted by ingesting food or water contaminated with the virus or by coming in contact with an infected person. While hepatitis A infections are usually mild, the virus can on rare occasions cause a severe, acute disease. Hepatitis A does not cause a chronic infection, as do hepatitis B and C. A vaccine is available to prevent hepatitis A.
Hepatitis B virus (HBV) is the most common cause of acute viral hepatitis. It is spread through contact with blood or other body fluids from an infected person. Exposure can occur, for example, through sharing of needles for intravenous drug use or through unprotected sex. People who live in or travel to areas of the world where hepatitis B is prevalent are at a greater risk. Rarely, mothers can pass the infection to their babies, usually during birth. The virus, however, is not spread through food or water, casual contact such as holding hands, or coughing or sneezing. A vaccine can be given to protect against hepatitis B.
Hepatitis C virus (HCV) is also spread by exposure to contaminated blood, primarily though the sharing of needles by intravenous drug users, but also by sharing personal items contaminated by blood such as razors, through sex with an infected person, via health care occupational exposure, and from mother to baby during childbirth. Before tests for HCV became available in the 1990s, HCV was often transmitted by blood transfusions. Currently, there is no vaccine to prevent infection with HCV.
Some of the hepatitis panel tests detect IgM antibodies. These are the first antibodies produced during the initial stages of infection. As the disease progresses or resolves, IgM antibody levels decrease. The panel also typically includes a test for hepatitis B surface antigen (HbsAg). This test detects proteins on the surface of the virus. HBsAg is the earliest indicator of an acute hepatitis B infection and is usually present even before symptoms appear, so this test is useful for screening those who are at high risk of infection or who may have been exposed. The test for hepatitis C antibody cannot distinguish between an active or previous infection and further testing is necessary to determine whether the infection is current.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.