What is HEPATITIS B SURFACE ANTIBODY - ANTI HBs?

Also Known As: HBV Tests, Hep B Test, Anti-HBs, Hepatitis B Surface Antibody, HBsAg, Hepatitis B Surface Antigen, HBeAg, Hepatitis B e Antigen, Anti-HBc, Hepatitis B Core Antibody, Anti-HBc, IgM anti-HBe, Hepatitis B e Antibody, HBV DNA

Formal Name: Hepatitis B Virus Testing

Hepatitis B is inflammation of the liver that is caused by an infection with the hepatitis B virus (HBV). Testing for hepatitis B provides information about a current or past infection with HBV.

Hepatitis B testing is performed on a blood sample. Testing may be used to diagnose hepatitis B, to assess its severity, and to determine whether a person has immunity to this disease.

Hepatitis B is a viral infection that causes inflammation of the liver. Hepatitis B test results can identify present hepatitis B infection, past exposure to HBV, or immunity to the virus.

HBV is spread through contact with body fluids. Most frequently, it is spread from blood-to-blood contact, but it may be transmitted through other body fluids. Common forms of exposure to HBV vary based on geographical area but often occur during childbirth and infancy, when sharing needles for intravenous drug use, or during unprotected sex.

A hepatitis B infection can be acute or chronic. Acute hepatitis B is a short-lived infection. Most patients recover completely from acute hepatitis B without treatment within a few weeks to six months.

Around 5% to 10% of patients with acute hepatitis B progress to having chronic hepatitis B. Chronic hepatitis is a long-term infection lasting six months or longer. Patients with chronic hepatitis B are at an increased risk of developing complications, including damage to the liver, liver failure, and liver cancer.

A doctor may order hepatitis B testing for several purposes:

• Screening for HBV: Screening tests attempt to find a disease before a person develops symptoms. Many people with hepatitis B have no symptoms, so screening for this disease enables early detection so that patients can receive treatment and avoid unknowingly spreading the virus to others. Hepatitis B screening may be recommended for patients at an increased risk of contracting this infection.
• Diagnosing and evaluating HBV infection: Hepatitis B testing can identify whether a person has a current hepatitis B infection if an infection is acute or chronic and whether a person can spread the virus to others.
• Assessing past HBV infection and future immunity: Tests for hepatitis B can show whether a person is immune either due to HBV vaccination or due to having recovered from a past infection. Hepatitis B testing may also be used to assess whether vaccination successfully generated immunity and to identify patients who are at an increased risk of HBV reactivation.
• Monitoring HBV infections: Testing may be used after a person is diagnosed with hepatitis B to monitor the disease, detect complications, and assess response to treatment.

What does the test measure?

Hepatitis B testing looks for antigens, antibodies, or the genetic material of the hepatitis B virus. HBV antigens are substances from the virus that causes a patient’s body to produce an immune response. Antibodies are substances made by the immune system in response to the hepatitis B virus.

Initial tests for hepatitis B measure antibodies and antigens related to HBV including:

• Hepatitis B surface antigen (HBsAg): Hepatitis B surface antigens are proteins present on the surface of the hepatitis B virus. These proteins can be detected in high levels during both an acute or chronic hepatitis B infection. This test may be used to screen for, detect, and help diagnose acute and chronic HBV infections.
• Hepatitis B surface antibody (anti-HBs): In response to hepatitis B surface antigens, the body naturally produces hepatitis B surface antibodies within a few weeks or months. Detecting anti-HBs suggests that a patient has recovered from hepatitis B and is now immune to the disease. These antibodies are also detected in patients who have previous exposure to HBV, including through vaccination.
• Total hepatitis B core antibody (anti-HBc): Hepatitis B core antibodies appear as a patient develops symptoms of hepatitis, and they remain detectable for life. The results of this test are interpreted alongside other tests to assess recovery from a previous HBV infection and to differentiate between acute and chronic infections. This test detects two types of anti-HBc antibodies, called IgM and IgG anti-HBc antibodies.
• IgM Hepatitis B core antibody (IgM anti-HBc): This test detects only IgM anti-HBc antibodies. IgM Hepatitis B core antibody is detected only in acute hepatitis B infections within six months of infection.

If a patient is diagnosed with hepatitis B based on these initial tests, additional hepatitis B testing may be used to monitor the disease, guide treatment, and determine if a person can spread hepatitis B to others. These additional tests may include:

• Hepatitis B e antigen (HBeAg): Hepatitis B e antigen is a protein from the hepatitis B virus found in some patients who are positive for hepatitis B surface antigen. Measuring this antigen can help doctors understand infectivity, which describes a person’s ability to spread HBV to others.
• Hepatitis B e antibody (anti-HBe): Anti-HBe is an antibody produced by the body in response to the hepatitis B e antigen. The disappearance of HBeAg and detection of anti-HBe in the blood is called seroconversion and suggests improvement of the condition and predicts long-term clearance of the virus. Chronic liver disease is more common in patients with HBeAg and is less common in patients with anti-HBe, so this test may be used to monitor acute HBV infections.
• Hepatitis B viral DNA: A hepatitis B viral DNA test detects the virus’s genetic material and determines the viral load in the blood. A positive test indicates that the virus is multiplying in a person’s body, making that person contagious. The test is often used to monitor the effectiveness of antiviral therapy in people with chronic HBV infections.

When should I get hepatitis B testing?

Using hepatitis B tests to screen for HBV is recommended for certain groups that are at an increased risk of infection. Groups that may benefit from hepatitis B screening include:

• Pregnant people
• People born in parts of the world where hepatitis B is more common, including Africa, Asia, Eastern Europe, South America, and parts of the Middle East
• People who didn’t receive a hepatitis B vaccine
• HIV-positive people
• Users of injectable drugs
• People at risk of HBV infection due to sexual exposure

A doctor may order hepatitis testing based on a patient’s symptoms, medical and family history, and a physical exam. If patients develop symptoms without recent exposure to HBV, doctors may recommend an acute viral hepatitis panel that looks for hepatitis A, B, and C in one sample of blood.

Hepatitis tests may also be performed as follow-up tests when other tests of liver health are abnormal.

Testing is common in patients that show symptoms that could be caused by hepatitis B. Symptoms of hepatitis B include:

• Dark urine
• Fatigue
• Fever
• Gray- or clay-colored stools
• Pain in the joints or abdomen
• Loss of appetite, nausea, or vomiting
• Yellowish skin and eyes

Using hepatitis B testing to assess immunity to HBV may be used before or after vaccination. Pre-vaccination testing is not always needed but may be performed if there is a chance that a patient has previously been infected with HBV or has already been vaccinated. Post-vaccination testing is used in certain groups of people who are at an especially elevated risk for HBV infection, including infants born to mothers with a hepatitis B infection.

How to get tested

Hepatitis B testing is typically prescribed by a doctor and performed in a hospital, lab, or other medical settings. Taking a hepatitis B test requires a blood sample, which can be collected by a health care professional.

For laboratory-based testing, blood is drawn from a patient’s vein. After blood is collected, the sample is sent to a laboratory for analysis.

Can I take the test at home?

Samples for hepatitis B testing can be collected at home. At-home hepatitis B testing requires a patient to collect a blood sample, typically from a fingerstick using a very small needle provided in the test kit. Once a blood sample is collected, it is prepared according to the instructions contained in the test kit and mailed to a laboratory for testing.

Because there are numerous types of tests for HBV, it is important to look closely at the specific components of an at-home test kit. Many at-home test kits only look for hepatitis B surface antigen (HBsAg).