HBsAg Test

An HBsAg test is usually advised when the doctor suspects that you may have hepatitis. Many patients may be asymptomatic, or they may have mild symptoms like that of flu.          

In fact, symptoms are usually not seen in the early stages of infection. Hepatitis symptoms appear in case of chronic disease or severe conditions.

Common symptoms of HBV infection are:

• Extreme fatigue
• Fever
• Muscle pain
• Nausea
• Loss of appetite
• Yellow skin and eyes (jaundice)
• Abdominal pain
• Dark-coloured urine

HBsAg testing may also be advised:

• If you have a personal or family history of liver disease, cirrhosis or liver cancer
• For evaluation of abnormal liver functions
• If your family or household member suffers from hepatitis B or if you have had sexual contact with an HBV infected person
• To healthcare workers, such as doctors or nurses, and healthcare staff who are exposed to blood and bodily secretions
• Before blood transfusion, surgery or organ transplant
• To drug addicts or those who share needles and syringes    
• To children of mothers who are HBsAg positive
• To unvaccinated adults
• To pregnant women
• To those born in high prevalence in a country
• If you have multiple sexual partners. 
• To sex workers and to same sex couples
• To those infected with human immunodeficiency virus or hepatitis C infection or both

No preparation is required for this test.

It is a simple test in which a blood sample is taken from a vein in the arm. A volume of 5-10 mL is sufficient for the test. Possible but infrequent complications can be a pain, light-headedness, bruising and local infection in the arm.

HBsAg test outcome is correlated with other HBV-specific antigens and antibodies, such as anti-hepatitis B core antibody (HBc), anti-hepatitis B surface antibody (HBs), immunoglobulin M (IgM) anti-HBc, hepatitis B e antigen (HBe). The results are interpreted to determine acute or chronic infection, immunity due to a previous infection or vaccination or susceptibility.

Further tests may be conducted to determine the viral load and replication (HBV-DNA) in blood.

Normal results: HB antigen levels: <1 signal per cut-off [s/c]) indicate negative or normal results.

Abnormal results: A level of >1 s/c is considered positive or abnormal.

HBsAg is positive in acute and chronic infection, carrier state and infective state.

HBsAg is negative when a patient has never been infected or immunised; infection has resolved and when the patient is immune to the virus.

HBsAg can be detected between 1-9 weeks after exposure to the virus.

The amount of time within which HBsAg or HBV DNA is detected varies, although half the individuals will test negative for both HBsAg and HBV DNA 7 weeks after symptoms appear.

Those who spontaneously recover from HBV infection will test negative for HBsAg and HBV DNA 15 weeks after the onset of symptoms.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational perspective and is in no way a substitute for medical advice from a qualified doctor.