The Test Sample
What is being tested?
Hepatitis C (HCV) is a virus that causes an infection of the liver that is characterized by liver inflammation and damage. Hepatitis C tests are a group of tests that are performed to detect, diagnose, and monitor the treatment of a hepatitis C viral infection. The most common test for HCV looks for antibodies in the blood that are produced in response to an HCV infection. Other tests detect the presence of viral RNA, the amount of viral RNA present, or determine the specific subtype of the virus.
Hepatitis C is one of six hepatitis viruses identified so far, including A, B, D, E, and G, that are known to cause the disease. HCV is spread by exposure to contaminated blood, primarily though the sharing of needles by intravenous drug users, but also by sharing personal items contaminated by blood such as razors, through sex with an infected person, via health care occupational exposure, and, less commonly, from mother to baby during childbirth. Before tests for HCV became available in the 1990s, HCV was often transmitted by blood transfusions.
While HCV is not as contagious as Hepatitis B, there is currently no vaccine to prevent infection. Hepatitis C infection is a common cause of chronic liver disease in North America. An estimated 4.1 million people in the United States have been exposed to the virus, and 3.2 million people are living with a current infection. Up to 85% of those who have it will become chronically infected after their acute infection resolves.
Many of those who are infected have no symptoms and are not aware of the condition. The acute HCV infection may cause few to mild nonspecific symptoms, and the chronic infection may simmer quietly for a decade or two before causing sufficient liver damage to affect liver function.
Hepatitis C infections cause increased risk of developing some other serious conditions:
- About 60-70% of those infected will develop chronic liver disease.
- About 5-20% will develop cirrhosis over 20 years; recent projections suggest that almost 45% will eventually develop cirrhosis.
- HCV causes death in about 1-5% of those chronically infected who develop cirrhosis or liver cancer.
Hepatitis C antibody tests are used to screen individuals for the infection, including, for example, people with no signs or symptoms but with risk factors, people who have symptoms associated with hepatitis or liver disease, or those who have been exposed to the virus. Since the antibody test can remain positive in most people even if they have cleared the infection, a positive antibody test is followed by a hepatitis C RNA test, which detects genetic material of the virus. A positive result on the RNA test means the virus is present, the infection has not resolved, and the person may require treatment. The hepatitis C genotype test determines which type of virus is present to help guide treatment.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the 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.