Hepatitis B Surface Antigen (HBSAG)
Fast, reliable detection of active hepatitis B infection.
This test detects the hepatitis B surface antigen (HBsAg), a protein found on the outer surface of the hepatitis B virus. Its presence in the blood is the earliest and most reliable indicator of an active hepatitis B infection, whether acute or chronic. The test is suitable for anyone concerned about possible exposure to hepatitis B, including individuals with known risk factors, those undergoing routine sexual health screening, pregnant women, healthcare workers, and people who have been in contact with someone diagnosed with the virus. It is also used to monitor the progress of those already known to be infected.
The assay is performed using a validated immunoassay technique, which provides high sensitivity and specificity for detecting HBsAg in a simple blood sample.
What is screened
- Hepatitis B surface antigen (HBsAg): The primary marker of current hepatitis B infection. A positive result indicates that the virus is present and the individual is capable of transmitting it to others. A negative result generally means no active infection, though it does not confirm immunity or exclude very early or resolved infection.
Why it matters
Hepatitis B can lead to serious long-term liver complications, including cirrhosis and liver cancer, yet many people remain unaware they are infected because symptoms may be absent or mild. Early detection through HBsAg testing allows timely medical assessment, appropriate monitoring, and access to treatment that can reduce the risk of liver damage and prevent onward transmission. This test provides a clear, actionable answer about your current infection status, empowering you and your clinician to make informed decisions about your health.
- Hepatitis B surface antigen (HBsAg)
No special preparation required.
For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.
Important Clinical Information:
This test is a screening tool to monitor and support your overall health. It does not replace your GP or Consultant.
Always discuss your test results, especially any abnormal results, with your GP, who can interpret them in the context of your medical history and overall health.