Hepatitis B s (Surface) Antigen, Quantitative

The Hepatitis B s (Surface) Antigen, Quantitative measures the amount of hepatitis B surface antigen (HBsAg) in the blood. This test helps determine if an individual is currently infected with the hepatitis B virus (HBV) and gauge its severity and monitor treatment response.

Hepatitis B is a serious liver infection caused by the hepatitis B virus (HBV). It can spread through contact with infected body fluids like blood, saliva, vaginal fluids and semen. It can also be passed from a mother to her baby during childbirth.

HBsAg is a protein on the surface of HBV that can be detected in high levels in serum during acute or chronic HBV infection. This antigen can be found in your blood within several weeks after the infection starts and therefore serves as one of the earliest markers of a hepatitis B infection. Most infected individuals do not exhibit any symptoms following initial infection. However, some common symptoms are fever, nausea, vomiting, loss of appetite, stomach pain, joint pain, dark-colored urine, light-colored stool, and the yellowing of skin and eyes (jaundice). 

The Hepatitis B s (Surface) Antigen, Quantitative test is typically advised for individuals diagnosed with chronic Hepatitis B to monitor the viral load (amount of virus) and evaluate the effectiveness of antiviral treatments. This test is also done during routine follow-up checkups to assess whether the virus is responding to therapy or if adjustments in treatment are necessary. Additionally, the test can be used to gauge disease progression in individuals with high HBsAg levels, which might indicate more severe infection or an increased risk of complications. It may be recommended before starting treatment to establish a baseline viral load and periodically thereafter to track changes in viral activity. In some cases, it is also used to aid in decision-making regarding the need for long-term management or potential interventions to prevent the progression of liver disease.

An elevated HBsAg levels generally signify a higher viral burden, which can be indicative of active infection and increased risk of transmission. Conversely, lower HBsAg levels may suggest a response to antiviral treatment or a reduction in viral replication. 

No special preparation is needed for this test. You may eat and drink as per your daily routine. However, inform the doctor about any medications that you are taking or if you have a history of any bleeding disorders or recent vaccinations, as these factors may influence the test results. 

Lab test results may vary across laboratories. Abnormal test results require an expert interpretation; therefore, don't self-medicate at home solely based on these results, and always consult a doctor for a proper understanding of the test results.