Tests and diagnosis

By Mayo Clinic Staff

Screening healthy people for hepatitis B

Doctors sometimes test certain healthy people for hepatitis B infection. This is recommended because hepatitis B infection often begins damaging the liver before it causes signs and symptoms. Testing for hepatitis B infection in people who have a high risk of coming in contact with the virus may help doctors begin treatment or recommend lifestyle changes that may slow liver damage.

People who may want to talk to their doctors about screening for hepatitis B infection include:

  • Anyone who lives with a person who has hepatitis B infection
  • Anyone who has had sex with a person who has hepatitis B infection
  • Anyone with an unexplained, abnormal liver enzyme test
  • Anyone infected with HIV
  • Immigrants, including internationally adopted children, from areas of the world where hepatitis B is more common, including Asia, the Pacific Islands, Africa and Eastern Europe
  • People who inject drugs
  • Inmates
  • Men who have sex with men
  • People who have one or both parents from an area of the world where hepatitis B is more common
  • People who receive kidney dialysis
  • People who take medications that suppress the immune system, such as anti-rejection medications used after an organ transplant
  • Pregnant women

Blood tests to detect hepatitis B infection

Blood tests used to diagnose hepatitis B infection include:

  • A test to determine whether you can easily pass HBV to others. The hepatitis B surface antigen (HBsAg) test looks for hepatitis B surface antigen — part of the outer surface of the virus. Testing positive for this antigen means you have an active hepatitis B infection and can easily pass the virus to others. A negative test means you're probably not currently infected.
  • A test to determine whether you're immune to HBV. The antibody to hepatitis B surface antigen (anti-HBs) test determines if you have antibodies to HBV. Having antibodies can be due to a prior HBV infection from which you've recovered. Or, it can mean you may already have been vaccinated. In either case, a positive anti-HBs test means you can't infect others or become infected yourself because you're protected by the vaccine or your own natural immunity.
  • A test to determine whether you have had or currently have a hepatitis B infection. The antibody to hepatitis B core antigen (anti-HBc) test identifies people who have an HBV infection. If you test positive for hepatitis B core antibodies, you may have a chronic infection that you can transmit to others. A positive result may also mean you're recovering from an acute infection or have a slight immunity to HBV that can't otherwise be detected. How this test is interpreted often depends on the results of the other two tests.

Additional tests to gauge liver health and infection severity

If you receive a diagnosis of hepatitis B, your doctor may perform tests to check the severity of the HBV infection as well as the health of your liver. These tests include:

  • A test to determine how likely you are to spread HBV to others. The E antigen blood test looks for the presence of a protein secreted by HBV-infected cells. A positive result means you have high levels of the virus in your blood and can easily infect others. If the test is negative, you have lower blood levels of HBV and are less likely to spread the infection.
  • A test to determine how much HBV DNA is in your blood. The hepatitis B DNA test detects parts of HBV DNA in your blood, indicating how much virus is present (viral load). Assessing your viral load can help monitor how well antiviral therapy is working.
  • Tests to measure liver function. Liver function tests may gauge the amount of damage that has occurred in your liver cells.

Removing a sample of liver tissue for testing

During a liver biopsy, your doctor inserts a thin needle through your skin and into your liver. A small sample of liver tissue is removed for laboratory analysis. A biopsy may show the extent of any liver damage and may help determine the best treatment for you.

Sep. 01, 2011