What are they?

Hepatitis B virus tests are blood tests that check for substances (antibodies) in your blood that show whether you have hepatitis B now or had it in the past. The tests can help tell you if you may have the disease long-term. It also can show how bad it is and how easily it can be spread. It also can show if you are protected from getting the disease.

Antibodies can take weeks or months to develop. So a test done early in the infection may show an infected person doesn't have it.

Why are these tests done?

You may need testing if:

• You have symptoms of hepatitis.
• You may have been exposed to the hepatitis B virus. You are more likely to have been exposed to the virus if you inject drugs, have many sex partners, or are likely to be exposed to body fluids (such as if you are a health care worker).
• You've had other tests that show you have liver problems.
• You are pregnant.
• You or your doctor wants to know if you are protected from getting the disease.

The tests also are done to help your doctor decide about your treatment and see how well it's working.

How do you prepare for the test?

In general, there's nothing you have to do before this test, unless your doctor tells you to.

How is the test done?

A health professional uses a needle to take a blood sample, usually from the arm.

What happens after these tests?

• You will probably be able to go home right away.
• Talk to your healthcare provider or an infectious disease specialist if your test is positive.