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Hepatitis C Virus Tests
Test Overview
Hepatitis C virus (HCV) test is a blood test that
looks for proteins (antibodies) or genetic material (RNA) of the virus that causes hepatitis C. These
proteins will be present in your blood if you have a hepatitis C infection now
or have had one in the past. It is important to identify the type of hepatitis
virus causing the infection, to prevent its spread and start the proper
treatment.
HCV is spread through infected blood.
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Anti-HCV antibody tests
look for antibodies to HCV in the blood, indicating an HCV infection has
occurred. This test cannot tell the difference between an acute or long-term
infection. The enzyme immunoassay (EIA) may be the first test done to detect
anti-HCV antibodies.
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HCV RIBA is an
additional test that detects antibodies to HCV. This test can tell whether a
positive result was caused by an actual HCV infection or whether the result was
a
false-positive. This test may be done to double-check
a positive EIA test result.
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HCV genetic
material (RNA) testing uses polymerase chain reaction (PCR) to identify an
active hepatitis C infection. The RNA can be found in a person's blood within 1
to 2 weeks after exposure to the virus. HCV RNA testing may be done to
double-check a positive result on an HCV antibody test, measure the level of
virus in the blood (called viral load), or show how well a person with HCV is
responding to treatment.
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HCV quantitative
test (also called viral load) is often used before and during treatment to find
out how long treatment needs to be given and to check how well treatment is
working.
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HCV viral genotyping is used to
find out which genotype of the HCV virus is present. HCV has 6 genotypes, and
some are easier to treat than others.
There is no vaccine available to prevent hepatitis C.
Why It Is Done
Hepatitis C virus testing is done to:
- Identify the type of hepatitis C virus causing
the infection.
- Screen people (such as doctors, dentists, and
nurses) who have an increased chance of getting or spreading a hepatitis C
infection.
- Screen potential blood donors and donor organs to
prevent the spread of hepatitis C.
- Find out if a hepatitis C
infection is the cause of abnormal liver function tests.
How To Prepare
You do not need to do anything before you have this test.
Talk to your doctor about any concerns you have regarding the need
for the test, its risks, how it will be done, or what the results will mean. To
help you understand the importance of this test, fill out the
medical test
information form
(What is a PDF document?)
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How It Is Done
The health professional taking a sample of your blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the needle site, and then
put on a bandage.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band
is wrapped around your upper arm. It may feel tight. You may feel nothing at
all from the needle, or you may feel a quick sting or pinch.
Risks
There is very little chance of a problem from having blood sample
taken from a vein.
- You may get a small bruise at the site. You
can lower the chance of bruising by keeping pressure on the site for several
minutes.
- In rare cases, the vein may become swollen after the
blood sample is taken. This problem is called phlebitis. A warm compress can be
used several times a day to treat this.
- Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.
Results
The
hepatitis C virus (HCV) test is a blood test that
looks for proteins (antibodies) the body makes against HCV
or for the genetic material (RNA) of the hepatitis C virus.
Results of hepatitis C virus testing that show no infection are
called negative. This means that no antibodies against HCV or HCV genetic
material was found. Results are usually available in 5 to 7 days.
Hepatitis C virus tests
| Normal (negative): |
No hepatitis C antibodies are found.
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No hepatitis C genetic material (RNA) is found.
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| Abnormal (positive): |
Hepatitis C antibodies are found. A test to detect HCV RNA is
needed to determine whether the infection is current or occurred in the past.
If HCV RNA is found, genotyping can determine which strain of HCV is causing
the infection.
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Hepatitis C genetic material (RNA) is detected. This result
indicates a current hepatitis C virus infection.
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What Affects the Test
Many conditions can change HCV antibody levels. Your doctor will
talk with you about any abnormal results that may be related to your symptoms
and medical history.
Your results may need to be rechecked if you are taking some herbs
or other natural products.
What To Think About
- There is no vaccine at this time to prevent
infections with the hepatitis C virus.
- Hepatitis antibodies can
take weeks to develop, so your results may be negative even though you have the
early stages of an infection (false-negative).
- All
donated blood and organs are tested for hepatitis C before being
used.
- Other tests that show how well the liver is working are
usually done if your doctor thinks you may have hepatitis C. These may include
blood tests for bilirubin, alkaline phosphatase, alanine aminotransferase, and
aspartate aminotransferase. For more information, see the medical tests
Bilirubin,
Alkaline Phosphatase,
Alanine Aminotransferase (ALT), and
Aspartate Aminotransferase (AST).
- Many
states require that some types of hepatitis infections be reported to the local
health department. The health department can then send out a warning to other
people who may have been infected with the hepatitis virus, such as those who
are close contacts of someone who has hepatitis C.
- A home test kit
is available for hepatitis C (HCV). The kit contains a sharp instrument
(lancet) that you use to draw a small sample of blood from your fingertip. The
blood sample is then placed on a piece of collection paper and mailed in a
prepaid envelope to a lab for testing. Results are available in 10 days. You
are given an identification number to use when calling a toll-free number to
obtain confidential results. If the results of the test are positive, it is
important for you to make an appointment with your health professional to
confirm the test results, determine the amount of damage to your liver, and
determine whether antiviral therapy is an option.
References
Other Works Consulted
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Centers for Disease Control and Prevention (2003).
Guidelines for laboratory testing and result reporting of antibody to hepatitis
C virus. MMWR, 52(RR-03): 1–16. Available online:
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5203a1.htm.
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Pagana KD, Pagana TJ (2006). Mosby’s
Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis:
Mosby.
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Scott JD, Gretch DR (2007). Molecular diagnostics of
hepatitis C virus infection: A systematic review. JAMA,
297(7): 724–732.
Credits
| Author | Maria G. Essig, MS, ELS |
| Editor | Susan Van Houten, RN, BSN, MBA |
| Associate Editor | Pat Truman, MATC |
| Primary Medical Reviewer | Kathleen Romito, MD - Family Medicine |
| Specialist Medical Reviewer | W. Thomas London, MD - Hepatology |
| Last Updated | August 27, 2007 |
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| Author: | Maria G. Essig, MS, ELS | Last Updated: August 27, 2007 |
| Medical Review: | Kathleen Romito, MD - Family Medicine
W. Thomas London, MD - Hepatology |
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