Hepatitis B Virus Tests

Hepatitis B virus (HBV) tests check for substances in the blood that show whether a hepatitis B infection is active or has occurred in the past. The tests look for different signs of infection (markers):

• Antigens are markers made by bacteria or viruses. So the presence of HBV antigens means that the virus is in the body.
• Antibodies are proteins produced by the body to fight infection. The presence of HBV antibodies means that you have been exposed to the hepatitis B virus at some time. But you could have been infected long ago and gotten better, or you may have a current infection.
• Genetic material (DNA) of the hepatitis B virus shows that the virus is in the body. The amount of DNA can help determine how severe the infection is and how easily the HBV infection can be spread.

It is important to identify the type of hepatitis virus causing infection to prevent its spread and choose the proper treatment.

Hepatitis B virus (HBV) testing

HBV is transmitted through infected body fluids, including blood, semen, and vaginal fluids (including menstrual blood). It also can be transmitted from a pregnant woman to her child at or near the time of birth.

There are several different HBV tests. These are the HBV tests most commonly done:

• Hepatitis B surface antigen (HBsAg) is the earliest indicator of an active hepatitis B infection. This antigen may be present before symptoms of an HBV infection are present. If this antigen level remains high for more than 6 months, then you will probably become a carrier of HBV, meaning you can transmit it to others throughout your life.
• Hepatitis B surface antibody (HBsAb) usually appears about 4 weeks after HBsAg disappears. The presence of this antibody means that the infection is at the end of its active stage and you cannot pass the virus to others (you are no longer contagious). This antibody also protects you from getting HBV again in the future. The test is done to determine the need for vaccination—the antibody will be present after receiving the HBV vaccine series, showing that you have protection (immunity) from the virus. Occasionally your test may show that you have both the HBsAb and HBsAg antibodies. In this case, you are still contagious.
• Hepatitis B e-antigen (HBeAg) is an HBV protein that is only present during an active HBV infection. This test determines how contagious you are. Testing for this antigen can also be used to monitor the effectiveness of treatment for HBV.
• HBV DNA testing checks for genetic material (DNA) from the hepatitis B virus. The HBV DNA tests measure how much genetic material is present. A high level of HBV DNA means that the virus is multiplying in your body and you are very contagious. If you have a chronic HBV, an elevated viral DNA level means you are at an increased risk for liver damage and may want to consider treatment with antiviral medicine. Testing for HBV DNA is also used to monitor the effectiveness of treatment for chronic HBV infection. HBV DNA testing is a more sensitive test than HBeAg (above) for detecting HBV in the blood.

Other HBV tests are not done as often:

• Hepatitis B core antibody (HBcAb) is an antibody to the hepatitis B core antigen that appears about 1 month after an active HBV infection. It can be found in people who had an infection in the past and in those with long-term (chronic) HBV. It usually is present for life. Blood banks test for this antibody when screening donated blood for hepatitis B.
• Hepatitis B core antibody IgM (HBcAbIgM) is another antibody to the hepatitis B core antigen. It indicates an HBV infection that has occurred within the last 6 months.
• Hepatitis B e-antibody (HBeAb) shows that the active stage of an acute HBV infection is almost over, and your risk of being contagious is greatly reduced.

A hepatitis B vaccine is available to prevent an HBV infection.

Hepatitis D virus (HDV) testing

Infection with the hepatitis D virus (HDV), or delta agent, occurs only in people who are already infected with the hepatitis B virus (HBV). Vaccination against hepatitis B will prevent hepatitis D infection. Hepatitis D infection is rare in the United States and Canada, except among people who inject illegal drugs and those who are frequently exposed to blood products. The hepatitis D test detects HDV antibodies. A positive test indicates only that you have been infected with HDV—it cannot distinguish between an acute or chronic infection. Another test, the HDV RNA test, is needed to determine whether you have an active HDV infection. It does not distinguish between an acute or chronic infection. This test currently is not available except in research settings.

Since hepatitis B infections can be spread through sexual contact, practice safe sex until your test results are returned.

Hepatitis B virus testing is done to:

• Identify the type of hepatitis B virus infection. Testing can determine whether an infection has occurred recently or in the past. Other tests that indicate how well the liver is functioning are usually done to help make treatment decisions.
• Screen people who have an increased risk of getting or spreading a hepatitis B infection, such as doctors, dentists, and nurses.
• Screen blood donors and donor organs to prevent the spread of hepatitis B.
• Find out if a person has developed antibodies after receiving vaccinations for hepatitis B. The presence of antibodies to hepatitis B virus (HBsAb) means that the vaccinations were effective.
• Find out if abnormal liver function tests are being caused by hepatitis B.
• Monitor how well treatment of chronic hepatitis B is working.

No special preparation is needed before having hepatitis virus testing.

Talk to your health professional about any concerns you have regarding the need for the test, its risks, or how it will be done. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

The health professional drawing blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Apply a gauze pad or cotton ball over the needle site as the needle is removed.
• Apply pressure to the site and then a bandage.

You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. But many people do not feel any pain (or have only minor discomfort) after the needle is positioned in the vein. The amount of pain you feel depends on the skill of the health professional drawing the blood, the condition of your veins, and your sensitivity to pain.

Blood test

There is very little risk of complications from having blood drawn from a vein.

• You may develop a small bruise at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the needle is withdrawn.
• In rare cases, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is usually treated with a warm compress applied several times a day.
• Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medications can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medication, tell your health professional before your blood is drawn.

Hepatitis B virus tests check for substances in the blood that show a hepatitis infection is active or has occurred in the past. The tests look for antigens or genetic material (DNA) of the virus that causes hepatitis. Some tests also look for antibodies that the body makes against the virus. Normal results of hepatitis virus testing are called negative. This means that no antigens, antibodies, or genetic material related to the hepatitis B virus was found.

Abnormal (positive)

Your doctor will talk with you about anything that may stop you from having the test or that may change the test results.

• Hepatitis B can be prevented by vaccination. The presence of antibodies to the hepatitis B virus may indicate that you have developed immunity to the infection after being vaccinated. The hepatitis B vaccination protects against hepatitis D infection also.
• Hepatitis antibodies can take weeks or months to develop, so a person infected with hepatitis may initially test negative if testing is done early in the infection.
• People who have received the hepatitis B vaccine can have HBsAb antibodies without having any of the other hepatitis B markers (HBcAb, HBeAb, HBsAg, HBeAg, and HBV DNA). But a vaccinated person who is exposed to someone with an HBV infection may have a positive HBcAb test.
• All donated blood and organs are tested for hepatitis before being used.
• Other tests that indicate how well the liver is working are usually done along with hepatitis B tests. Examples include measurement of bilirubin, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase. For more information, see the medical tests Bilirubin, Alkaline Phosphatase, Alanine Aminotransferase (ALT), and Aspartate Aminotransferase (AST).
• In many states, some types of hepatitis infections must be reported to the local health department. The health department can then issue a warning to other people who may have been infected with the hepatitis virus, such as those who are close contacts of someone with hepatitis B.

Other Works Consulted

• Chernecky CC, Berger BJ, eds. (2004). Laboratory Tests and Diagnostic Procedures, 4th ed. Philadelphia: Saunders.

• Fischbach FT, Dunning MB III, eds. (2004). Manual of Laboratory and Diagnostic Tests, 7th ed. Philadelphia: Lippincott Williams and Wilkins.

• Pagana KD, Pagana TJ (2006). Mosby’s Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis: Mosby.