False Positives and Hepatitis C Testing: What You Should Know
If your doctor suggests that you be tested for hepatitis C, there are several steps that you must take before you know with certainty whether or not you actually have the virus. This is to be sure that your diagnosis is as accurate as possible.
In the early stages, it is possible for tests to indicate that you have hepatitis C, even though you really do not. That is called a false positive. A false positive result means that a test has incorrectly detected an illness or disease in someone who does not have that condition.1,2
It is important to know the difference between true and false positives.
Who should get tested for hepatitis C?
- Anyone who has used drugs, currently or in the past
- People born between 1945 and 1965 ("Baby Boomers")
- Recipients of blood transfusions or organ transplants before July 1992
- Long-term hemodialysis patients
How are people tested for hepatitis C?
The only way to know if you have hepatitis C is to get tested. Before you have a final diagnosis, you may need more than one type of test.
The first step is for you to take a blood test, called a hepatitis C antibody test. This test can tell if you have ever been infected with the hepatitis C virus. Antibodies are chemicals that are found in the blood when someone is infected with the virus.1
There are two possible antibody test results:1
- Non-reactive, or a negative - means that a person has never had hepatitis C
- Reactive, or a positive - means that hepatitis C antibodies were found in the blood. This could be because the person has been infected with the hepatitis C virus at some point in time.
The antibody test cannot tell whether the person currently has an active hepatitis C infection, or simply had it in the past.2 Once someone has been infected with hep C, they will always have antibodies in their blood - Even if they no longer have the hepatitis C virus.1
A reactive, or positive, antibody test requires another test to confirm whether the virus is still present in the person’s blood.1
How often do false positives happen?
If you test positive for hepatitis C antibodies, the next step is to be tested for the actual hepatitis C virus. This is because the antibody test sometimes gives false positive results.
In 2017, a study was conducted to see how often false positive results happen with hepatitis C antibody tests.2 In the study, researchers found that the test gave false positive results to 22 percent of people who were tested.2
A positive test result does not always mean that a person has an active hepatitis C infection. People with a low risk of having this infection are more likely to receive false positive results from the test. False positive results can also occur in children who were infected with the hepatitis C virus when they were born because their mother had a hepatitis C infection.2
Because false positives are possible, doctors confirm all positive antibody test results with additional testing for the hepatitis C virus.2 The tests to check for the hepatitis C virus are very accurate, and are used to make a final diagnosis.
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