HBsAg (Quantitative)

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

The test is used to diagnose and monitor hepatitis B infection. It may also be used to assess the effectiveness of hepatitis B vaccination or to evaluate the risk of transmitting the virus to others.

When this test is required

A doctor may order a quantitative HBsAg test if a patient has signs or symptoms of hepatitis B infection, such as abdominal pain, jaundice, or fatigue. The test may also be used to monitor the progression of the disease or the effectiveness of treatment. Additionally, healthcare workers or individuals at high risk of exposure to hepatitis B may be tested regularly to detect infection early and prevent the spread of the virus.

What the Test Detects

–

Preparation for the Test

No specific preparation is needed for the test. However, patients should inform their healthcare provider of any medications, supplements, or medical conditions they have that may affect the results of the test. Some medications, such as immunosuppressive drugs, may cause a false-negative result, while others, such as interferon, may cause a false-positive result.

Sample Requirements

The test requires a blood sample, which is usually drawn from a vein in the arm.

Additional Notes

False-positive and false-negative results are possible with the HBsAg test. False-positive results may occur in individuals who have been vaccinated against hepatitis B or who have a recent or ongoing infection with a different virus. False-negative results may occur in individuals with a weak immune response or in individuals taking immunosuppressive drugs.

Selected Tests