Additional Hepatitis B Blood Tests
Hepatitis B can be a complicated liver infection to understand, so additional blood tests may be ordered so your health provider has a better understanding of what kind of care and follow-up is needed.
Anti-HBc IgM or anti-HBc IgG (anti-hepatitis B core IgM or IgG)
Sometimes an anti-HBc IgM or anti-HBc IgG blood test may be ordered to clarify if a person has a new “acute” hepatitis B infection or “chronic” infection.
- A positive/reactive anti-HBc IgM test result usually indicates a new acute infection.
- A positive/reactive anti-HBc IgG test usually indicates a chronic infection.
These test results must be explained by your health care provider because they can be confusing. For example, sometimes the liver of a person who is chronically infected with hepatitis B may become more inflamed than usual (this is called a “liver flare”). So a chronically infected person could also test positive for the anti-HBc IgM blood test, although this usually indicates a new infection
Thus, it is important to be seen by a health care provider who understands hepatitis B so you get the right diagnosis and the right care and follow-up.
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. It associated with a chronic hepatitis B infection as well. This blood test detects how much virus is in the blood as a result of very active viral reproduction (or “viral replication”). It also determines how infectious a person may be.
- 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 not infectious; sometimes this can indicate a person has a mutant hepatitis B virus (see below).
The hepatitis B e-antigen test result is often used to monitor the effectiveness of many 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 means that the hepatitis B drug successfully 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.
To make things a bit more confusing, however, there are some chronically infected patients who are untreated and still test “negative” for the hepatitis B e-antigen. So, the absence of e-antigen does not always mean there is no active viral replication. Instead, these persons have a mutant hepatitis B virus that does not produce the e-antigen. As a result, treating someone who is e-antigen negative (but with a high viral load) is difficult because the mutant hepatitis B virus is more resistant to the current drugs. In addition, the absence of e-antigen makes it harder to evaluate whether a drug is working or not.
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 understood, but it is generally considered to be a good thing. For those with e-antigen negative chronic hepatitis B infections (meaning they have a mutant virus), the presence of anti-HBe may still be associated with active viral replication.
Hepatitis B Virus DNA Quantification (“viral load”) – This blood test measures the amount of hepatitis B virus DNA (or viral load) in the blood of chronically infected patients. 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 virus in the blood. It is not yet an approved test in the U.S. Outside the U.S. it is approved in many countries and is often ordered instead of the hepatitis B virus DNA blood test which is much more expensive or not available.
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 patient’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.
The hepatitis B virus specifically attacks the liver, so health care providers will order blood tests to monitor the health of your liver. Some of the most common liver related blood tests are described below.
Liver Function Tests (or Liver Enzymes) – These blood tests measure potential liver damage (or liver inflammation). If a person is infected with the hepatitis B virus, the liver cells can be injured by the virus and then the liver enzymes can leak into the bloodstream. The higher the number, the greater the risk of potential liver damage.
- ALT (alanine aminotransferase) is found almost exclusively in the liver and is monitored most closely in a chronic hepatitis B infection. This test is useful in deciding whether a patient would benefit from treatment or for evaluating how well a person is responding to therapy. The upper limits of normal for ALT in healthy adults is 30 U/L for men and 19 U/L for women.
- AST (aspartate aminotransferase) is found in the liver, heart and muscle so is less accurate than the ALT in measuring liver damage. But this enzyme is often ordered to help monitor potential liver damage from the hepatitis B virus.
AFP (Alpha-FetoProtein) - This is a normal protein produced in the developing fetus, thus, pregnant women will have elevated AFP. Other adults, however, should not have elevated AFP in their blood. This test is used to screen for primary liver cancer patients with chronic hepatitis B. Patients should have their AFP levels monitored at every visit since hepatitis B is the leading cause of liver cancer. If the AFP level is high, the health care provider will order more blood tests and imaging studies.
Ferritin - Iron is stored in the liver in the form of ferritin. Increased levels of ferritin indicate that a high level of iron is being stored. This could result from an increased iron intake in the diet (vitamin supplements, food cooked in iron pots, etc.). For people living with chronic hepatitis B, a high level can indicate liver damage since ferritin is leaked into the bloodstream as liver cells are injured by the virus.
Additional Blood Tests Your Doctor May Order