Hepatitis B Surface Antigen (HBsAG) Blood Tests

Testing for the Hepatitis B Surface Antigen (HBsAg) is a crucial diagnostic tool used primarily for detecting an active Hepatitis B virus (HBV) infection.

A positive Hepatitis B Surface Antigen (HBsAg) test indicates an active infection with the hepatitis B virus (HBV). Here's what a positive result generally signifies:

  1. Active Infection: The presence of HBsAg in a blood test means that the hepatitis B virus is present and the person is currently infected. It is the first detectable viral antigen to appear after the initial infection.
  2. Infectious State: Individuals who test positive for HBsAg can transmit the virus to others through bodily fluids such as blood, semen, or vaginal secretions. This is particularly significant in medical settings, for pregnant women, and for those who live in close contact with others.
  3. Acute or Chronic Hepatitis B:
    • Acute Infection: If HBsAg is detected for a limited period (usually less than six months), it suggests an acute HBV infection. In many cases, acute infections resolve on their own, and the infected person's immune system clears the virus from the body, leading to a loss of HBsAg and the development of antibodies (anti-HBs) that provide immunity against future infections.
    • Chronic Infection: If HBsAg remains in the blood for more than six months, it indicates a chronic HBV infection. People with chronic hepatitis B may require ongoing medical evaluation and treatment to manage the disease and prevent liver damage such as cirrhosis or liver cancer.
  4. Further Evaluation Needed: A positive HBsAg test typically prompts further diagnostic testing, including tests for hepatitis B e antigen (HBeAg), anti-HBc (antibody to hepatitis B core antigen), and possibly liver function tests to assess the extent of liver damage and the state of the infection (whether it is replicating).
  5. Monitoring and Treatment: For those with a chronic condition, regular monitoring and treatment are crucial to manage the disease and prevent serious complications. Antiviral medications can help fight the virus and slow its ability to damage the liver.

A positive HBsAg test result plays a critical role in the diagnosis and management of hepatitis B infections, guiding decisions regarding treatment, monitoring, and preventive measures to reduce transmission to others.