This hepatitis B test is used to help diagnose a hepatitis B infection, either acute or chronic, to monitor chronic hepatitis B patients and to detect previous exposure to hepatitis B. This test, specifically known as the hepatitis B surface antigen test (HBsAg), detects a specific antigen that is present on the surface of the hepatitis B virus (HBV). Hepatitis is characterized by inflammation and enlargement of the liver. It has several causes, one of which is a virus.
The hepatitis B virus is spread through contact with blood or other bodily fluids and is highly contagious. Those who share needles for drug use or engage in unprotected sex are at a high risk of contracting the disease. Exposure can also occur while traveling to other parts of the world where the disease is more prevalent. A vaccine is available and has been given to children and babies since 1991 but there are between 800,000 and 1 million or more people who are infected and many of them are not aware that they are infected. In the early or acute stages of the disease there may not be symptoms. Most people are able to clear this potentially serious infection from their bodies on their own, but some are not. Many of these people have no symptoms and carry the disease for the rest of their lives, exposing others to it and potentially causing severe liver damage and inflammation leading to cirrhosis or hardening of the liver or liver cancer.
A hepatitis B test is ordered when signs and symptoms of hepatitis B are present or if a possible exposure has taken place. Symptoms of hepatitis B include:
- Loss of appetite
- Nausea and/or vomiting
- Abdominal pain
- Dark urine
- Pale stools
- Joint pain
- Jaundice (yellowing of the skin and/or eyes)
If you know that you have been exposed to hepatitis B, an injection of hepatitis B immune globulin (HBIG) within 24 hours can prevent an infection. Chronic hepatitis B can be treated with antiviral medications but it is not always effective.
Why Do I Need It?
Hepatitis B screening should take place for those at an increased risk of exposure including men who have sex with men, IV drug users, health care workers, pregnant women and those who have not been vaccinated. Untreated and unresolved hepatitis B can cause long term damage to the liver including cirrhosis and liver cancer.
Understanding Hepatitis B Test Results
A negative test result indicates that you have not been exposed to the hepatitis B virus and you are not immune. It may be recommended that you receive the hepatitis B vaccine
A positive result may indicate one of the following:
- Immunity to the virus
- An acute or current infection with symptoms
- A previous infection and current immunity. In those who are immunocompromised the virus may reactivate.
- An acute or current infection that is resolving
- An active chronic or long term infection with liver damage
- A chronic infection but a low risk of liver damage; a carrier