Blood Tests
The hepatitis B e-antigen test result is often used to monitor the effectiveness of hepatitis B drug therapies that aim to change a chronically infected person’s e-antigen status from “positive” to “negative.” By achieving a “negative” e-antigen result, this can indicate that the hepatitis B drug stopped or slowed down the virus replication. Although this is not a cure, stopping or slowing down the virus will result in less damage to the liver, which decreases the risk of developing serious liver disease in the future.
HBeAg (Hepatitis B e-Antigen) - This is a viral protein made by the hepatitis B virus and is released from the infected liver cells into the blood. This test can detect how much virus is in the blood because of very active viral replication. A negative test result indicates the virus may not be actively reproducing in the liver. The loss of e-Antigen can occur naturally or as a result of drug treatment. Sometimes a negative test result can indicate a mutant hepatitis B virus is present. So, the absence of e-Antigen does not always mean there is little or no active viral replication. The doctor can confirm with additional tests.
- A positive HBeAg indicates high levels of virus in the blood and a person is considered infectious.
- A negative HBeAg indicates very low to no virus in the blood and a person is usually considered less infectious; sometimes this can indicate a person has a mutation of the hepatitis B virus (see below).
Most people with chronic hepatitis B will eventually lose hepatitis B e-antigen (HBeAg) and develop hepatitis B e-antibody (HBeAB), even without treatment. When this happens, there is often a reduction in the HBV viral load. Many may have a loss of HBeAg early in life, while others may be in their 40’s or older. Depending on the length of this time window, there is potential liver damage that may occur. This is why regular monitoring is very important.
To make things a bit more confusing, there are some chronically infected, untreated people who are HBeAg negative but still have a high HBV DNA viral load. So, the absence of e-antigen does not always mean there is no active viral replication. Instead, these persons have a mutation of the hepatitis B virus that does not produce the e-antigen. This is evident with an HBV DNA test but may also be noted with persistently elevated ALT levels. Once again regular monitoring is key.
Pregnant women who are HBeAg positive may require additional monitoring or antiviral treatment with an effective antiviral during the last trimester of pregnancy to prevent transmission to their babies during birth. If you are pregnant and living with hepatitis B, seek the guidance of a knowledgeable doctor as soon as you can.
anti-HBe or HBeAb (Hepatitis B e-Antibody) - This is not a protective antibody. It is made in response to the hepatitis B e-antigen. Chronically infected individuals who stop producing e-antigen sometimes produce e-antibodies. The clinical significance of this result is not fully characterized, but it is generally considered to be a good thing. For those with e-antigen negative chronic hepatitis B infections (meaning they have a mutated form of the virus), the presence of anti-HBe may still be associated with active viral replication.
Hepatitis B Virus DNA Quantification (“viral load” “HBV DNA”) – This blood test measures the amount of hepatitis B virus DNA (or viral load) in the blood of chronically infected people. The blood is tested using a Polymerase Chain Reaction (PCR) technique that is highly sophisticated and accurate. The hepatitis B “viral load” provides important information but should only be considered in relation to other information such as your e-antigen status and liver enzymes test results (see below). The viral load is usually measured in “international units per milliliter” (IU/mL), but may also be measured in “copies per milliliter” (cp/ml). There are approximately 5 copies in one international unit.
HBsAg Quantitative (quantitative hepatitis B surface antigen / qHBsAg) – This blood test measures the actual amount of hepatitis B surface antigen in the blood. When used in combination with the HBV DNA test, qHBsAg can provide a health care provider with additional insights into an individual’s HBV infection. It can also be used in predicting and monitoring treatment response. This test may not be available everywhere and may be cost prohibitive.
Hepatitis B Drug Resistance, Genotype, and BCP/PreCore Mutation – This blood test is not commonly ordered. A liver specialist may order the test to determine a person’s hepatitis B virus genotype (A-H) for research purposes and to detect a viral mutation that may be associated with resistance to current treatments. This is a Polymerase Chain Reaction test, which again, is not readily available or used outside large teaching hospitals.