Understanding the Hepatitis B Surface Antibody (anti-HBs) Test
What It Is: The Hepatitis B Surface Antibody (anti-HBs or HBsAb) test measures the level of antibodies against the Hepatitis B virus (HBV) in your blood. These antibodies are produced by the immune system in response to the Hepatitis B surface antigen (HBsAg) and indicate immunity to the virus.
Why It's Important: The presence of Hepatitis B surface antibodies indicates that you are protected against HBV infection, either due to vaccination or successful recovery from a previous HBV infection. This test helps determine your immunity status and whether you need vaccination or further medical evaluation.
Role of Hepatitis B Surface Antibodies:
Immunity Indicator: The presence of anti-HBs antibodies indicates immunity to HBV, either from vaccination or past infection.
Protection: Adequate levels of anti-HBs antibodies protect against HBV infection.
How the Hepatitis B Surface Antibody Test Works:
Sample Collection: A healthcare professional collects a blood sample from a vein in your arm.
Laboratory Analysis: The sample is processed in a lab where the level of anti-HBs antibodies is measured.
Interpreting the Results:
Protected: Anti-HBs greater than 10-12 milli-International Units per milliliter (mIU/mL) indicates protection against HBV infection.
Susceptible: Anti-HBs less than 5 mIU/mL indicates susceptibility to HBV infection and the need for vaccination.
Inconclusive: Anti-HBs levels between 5-12 mIU/mL are inconclusive, and the test should be repeated.
Why Your Doctor Might Order This Test:
Assessing Immunity: To determine if you are immune to HBV, either from vaccination or past infection.
Evaluating Vaccination Needs: To check if you need a Hepatitis B vaccine or a booster dose.
Monitoring Treatment: To monitor the effectiveness of treatment in individuals with chronic HBV infection.
Symptoms That Might Prompt This Test:
Exposure to HBV
Routine screening for healthcare workers
Pre-pregnancy or prenatal screening
Evaluation of liver function abnormalities