Measurement of hepatitis B virus surface antigen (HBsAg) is used to diagnose acute, recent, or chronic hepatitis B infection.
Hepatitis B virus (HBV), has an incubation period of 6 to 23 weeks (mean 17 weeks). It is mainly transmitted by blood and certain body secretions. Hepatitis B can also be transmitted through the use of infected needles. This form of hepatitis is more severe than hepatitis A. It damages the liver cells and can lead to cirrhosis and liver cancer. The treatment involves the use of interferon and antiviral drugs in an attempt to control the virus's proliferation. Vaccination for HBV provides protection for over 20 years.
Hepatitis B virus consists of an outer shell that surrounds an inner "core". The outer shell contains a protein called hepatitis B surface antigen (HBsAg) or Australian antigen. The inner core contains the hepatitis B core antigen (HBcAg). The inner core also contains another protein called antigen e (HBeAg). The human body reacts to the presence of these antigens by producing antibodies against them. Thus, laboratory testing includes tests for the presence of antigens as well as antibodies (HBsAb, HBcAb, and HBeAb).
Hepatitis B Surface Antigen (HBsAg)
This test (also called the Australian antigen) determines the hepatitis B virus surface antigen. It is used to screen blood donors and to diagnose hepatitis B. HBsAg measurement is the earliest indicator of hepatitis B and often increases before the onset of clinical symptoms. This antigen usually occurs 4 to 12 weeks after infection and is indicative of active hepatitis B. If HBsAg levels are consistently positive, the patient is considered to be a chronic carrier of hepatitis B. The negative test result indicates that a person has never been exposed to the virus or has recovered from acute hepatitis and is free from the virus. The positive result indicates active infection but does not indicate whether the virus can be transmitted to others.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
