8 Common Hepatitis B Diagnostic Tests

If we rely on external signs and symptoms, it is very difficult to determine whether a patient is infected with the hepatitis B virus or not. The most accurate diagnostic method is to perform hepatitis B diagnostic tests. Here are some commonly ordered testing methods.

Hepatitis B Surface Antigen (HBsAG) Test

HBsAG stands for Hepatitis B Surface Antigen. This test is the decisive method to determine whether a patient has hepatitis B or not. If the test result is positive, it means the patient is infected with hepatitis B. This method is divided into two types: qualitative HBsAG and quantitative HBsAG.

Qualitative HBsAG helps the doctor determine if the patient is infected with hepatitis B or not. However, the test result cannot indicate the status of the virus, such as whether it can develop and spread, and to what extent it affects the patient.

Quantitative HBsAG helps the doctor determine the concentration of the antigen, whether it is high or low, in order to prescribe appropriate treatment.

Hepatitis B Surface Antibody (HBsAb) Test

HBsAb stands for Hepatitis B Surface Antibody. If the HBsAb test result is positive, it means that the patient’s body has developed immunity against the hepatitis B virus.

This can happen if the patient had acute hepatitis B in the past or has been vaccinated against hepatitis B. Therefore, patients with a positive HBsAb test result do not need to receive hepatitis B vaccination again, and their bodies are fully capable of defending against the hepatitis B virus if it enters the body.

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Hepatitis B Core Antibody (HBcAb) Test

HBcAb, or Anti-HBc, stands for Hepatitis B Core Antibody. This test helps doctors assess whether a patient has been exposed to the hepatitis B virus.

If the test result is positive or reactive, it means the patient is currently or has been infected with the hepatitis B virus. However, Anti-HBc is only produced when the body is exposed to the hepatitis B virus and does not develop after receiving the vaccine.

Therefore, patients should be well-informed and avoid confusion between the two testing methods, HBcAc and HBsAb.

There are two types of HBcAb antibodies: IgM and IgG:

  • HBcAb IgM: These antibodies appear and increase rapidly during the acute phase of hepatitis B or an acute exacerbation of chronic hepatitis B. After the acute phase, the concentration of these antibodies in the blood gradually decreases.
  • HBcAb IgG: These antibodies appear during the chronic phase of hepatitis B infection.

HBV-DNA Testing

HBV-DNA testing is conducted to determine the quantity or concentration of the hepatitis B virus in a unit volume of serum IU/ml or copies/ml (where 1 IU is equivalent to 5-6 copies).

The concentration of the hepatitis B virus is considered high when this value is above 10,000 IU/ml, moderate when it falls between 2000 and 10,000 IU/ml, and low when it’s below 2000 IU/ml. Based on the test results, doctors can assess the level of the virus replicating within liver cells.

Patients with chronic hepatitis B should monitor HBV-DNA concentration in their blood monthly or yearly to manage the disease. This helps doctors determine the timing of treatment, monitor progress, and assess treatment cessation criteria.

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HbeAg Test

HBeAg is the abbreviation for Hepatitis B Envelope Antigen, which is the envelope antigen of the hepatitis B virus. HBeAg is a segment of the virus’s capsid envelope.

When the HBeAg test is positive, accompanied by elevated liver enzymes, it indicates that the hepatitis B virus is active and causing some damage to the liver. The risk of transmission is also high in this state.

A negative HBeAg result suggests that the hepatitis B virus is in a dormant state, temporarily inactive, and has minimal potential to cause liver damage. However, doctors still recommend regular check-ups every 3 months to monitor the patient’s health status and the virus’s activity.

Other Hepatitis B Diagnostic Tests

If a hepatitis B diagnostic test is positive, doctors may recommend additional liver function tests, including AST (GOT), ALT (GPT), GGT, ALP, and bilirubin levels such as Total Bilirubin (TB), Direct Bilirubin (DB), and Indirect Bilirubin (IB).

These tests are essential for accurately assessing the patient’s disease condition and determining the appropriate treatment.

Alpha-fetoprotein (AFP) Test

The Alpha-fetoprotein test is a diagnostic tool for liver cancer. In a normal state, there is a very low level of alpha-fetoprotein in the body. However, in conditions like liver cancer, pregnancy, hepatitis, or cirrhosis, AFP levels may rise, typically exceeding 25-300 UI/ml.

The AFP concentration provides guidance and reference but cannot definitively confirm liver cancer. Conversely, a normal AFP level cannot rule out the possibility of liver cancer, as up to 20-30% of primary liver cancer patients may have normal AFP levels.

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Precautions Before Hepatitis B Diagnostic Testing

Before undergoing hepatitis B diagnostic testing, patients can eat normally and do not need to fast.

However, patients should be aware of avoiding smoking, alcohol, and stimulants within 48 hours before the test. It is also important to inform the doctor about any medications they are currently taking, including herbal supplements and Western medicines, as these can impact the accuracy of the test results.

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