At a Glance
Why Get Tested?
To screen for and diagnose a hepatitis C virus infection and to monitor treatment of the infection
When to Get Tested?
If you may have been exposed to/have risk factors for the hepatitis C virus, such as through contact with infected blood, sexual relations with an infected person, IV drug use or you have symptoms associated with liver disease
Sample Required?
A blood sample taken from a vein in your arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
Hepatitis C is a virus that can infect and damage the liver. In most cases, it is contracted through exposure to blood (usually from sharing contaminated needles while injecting drugs or, before 1992, through a blood transfusion), through sex with an infected person, via healthcare occupational exposure and it can also be passed from mother to baby.
Many people who are infected with Hepatitis C are not aware they are as acute infection produces few to mild non-specific symptoms. However Hepatitis C can also exist as a chronic (longstanding) infection and you can show no signs of this for a number of years (even decades) but it can then cause significant liver damage. About 65-75% of those infected can develop chronic liver disease with 20-30% of these developing cirrhosis over many years.
Hepatitis C antibody is produced by the body in response to exposure to the hepatitis C virus (HCV). The most common test for HCV looks for these antibodies in your blood. Some first line tests are also looking for the hepatitis C antigen, which the virus itself produces, as well as your antibody response. Other tests detect the presence of and actual amount of virus present or determine the specific subtype of virus.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in your arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
The Test
How is it used?
Each of the most common tests have a slightly different purpose:
- Anti-HCV or combined HCV Antibody/Antigen tests detect the presence of antibodies/antigens to the virus, indicating exposure to HCV. These tests on their own may not be able to tell if you still have an active viral infection, only that you were exposed to the virus in the past. Usually, the test is reported as “positive” or “negative.” There is some evidence that, if your test is “weakly positive,” it may not mean that you have been exposed to the HCV virus. All positive results (weak or strong) will either be repeated by a second antibody/antigen test or possible by the RNA test (described below).
- HCV-RNA test identifies whether the virus is in your blood, indicating that you have an active infection with HCV. It is usually performed by a test called a qualitative HCV. The result is reported as a “positive” or "virus detected” if any virus is found; otherwise, the report will be “negative” or “not detected” if no virus is found. The test is also used after treatment to see if the virus has been eliminated from the body. These tests are seldom used now.
- Viral Load or Quantitative HCV tests measure the number of viral particles in your blood. Viral load tests are used before treatment to help determine how long treatment needs to be given (along with other factors, such as your age, gender, the changes seen in a liver biopsy, and genotype, discussed below). It is also used to follow response to treatment by comparing the amount of virus before, during and after treatment at time points dependant on what type and length of treatment is given. The aim is to get the levels of virus to undetectable/not detected.
- Viral genotyping is used to determine the kind, or genotype, of the virus present. There are 6 major types of HCV with the most common (genotype 1) being less likely to respond to treatment than genotypes 2 or 3 and usually requiring longer therapy (e.g. 48 weeks instead of 24 weeks). Genotyping is usually requested before treatment is started to determine what type and length of treatment may be required and give an idea of the likelihood of success.
When is it requested?
Hepatitis C infection is a common cause of chronic liver disease . About 65-75% of those infected will develop chronic hepatitis, and about 20-30% of those develop cirrhosis. HCV testing is recommended in the following cases:
- If you have ever injected illegal drugs
- If you received a blood transfusion or organ transplantation before mid-1992*
- If you have received clotting factor concentrates produced before 1987
- If you were ever on long-term dialysis
- For children born to HCV-positive women
- For health care, emergency medicine, and public safety workers after needlesticks, sharps, or mucosal exposure to HCV-positive blood
- For people with evidence of chronic liver disease
* The blood supply has been monitored in the UK since mid-1992, and any units of blood that test positive for HCV are rejected for use in another person. The current risk of HCV infection from transfused blood is less than 1 case per million transfused units.
A positive anti-HCV test will be confirmed with an alternative test, especially if the test is “weakly positive.” Qualitative HCV-RNA may be used when the antibody test is positive to see if the infection is still present. HCV viral load and genotyping will be performed to plan treatment and to monitor response to treatment.
What does the test result mean?
If the antibody test result is positive, you have probably been infected with hepatitis C, even if it was so mild you did not realise you had it.
A repeat antibody or antibody/antigen test will usually be requested or possibly a viral load.
A positive (or detectable) HCV RNA means that you are currently infected by HCV.
If no HCV viral particles are detected then the person either does not have an active infection or the virus is present in very low numbers.
Is there anything else I should know?
HCV antibodies usually do not appear until several months into an infection but will always be present in the later stages of the disease.
Ten percent of people with HCV have no recognised source for their infection. Sexual exposures account for 15% of HCV cases.
Common Questions
Ask a Laboratory Scientist
Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
