What is a PCR test?
This is also a blood test. The term PCR refers to the actual laboratory technique (polymerase chain reaction) that amplifies the viral genetic material to a level that can be detected. The technique is complex and consists of many stages and is therefore fairly expensive. In relation to the hepatitis C virus, this technique or related molecular techniques may be used to test for the following three factors:
- The presence or absence of the virus in the blood
- The level of virus present in the blood (viral load)
- The genotype of the virus
Presence or absence of the virus in the blood
A PCR test may be recommended for:
- People who have had a positive hepatitis C antibody test, or
- People who have had inconclusive hepatitis C antibody test results, or
- People who have a weakened immune systems (due to HIV/AIDS, for example) and wish to determine whether they are hepatitis C virus positive or not, or
- People who have experienced a risk exposure (such as a needle stick injury) and want to find out during the ‘window period' whether they have been infected with the hepatitis C virus.
The PCR test is also used for assessing someone for treatment and for monitoring his or her response to treatment. Like the hepatitis C antibody test, the PCR test cannot tell how long someone has been infected. Receiving a PCR negative result (that is, no virus is detected in the blood) is usually a very good indication that the person does not have the virus. However, in an extremely small number of cases it may still be present at undetectable levels.
The genotype of the virus
There are six genotypes (strains) of the hepatitis C virus and the particular genotype of hepatitis C that is causing an infection can also be determined after a PCR test. It is essential for people considering pharmaceutical treatment to know which genotype of the virus they are infected with, as this will determine the length of their treatment as well as the probabilities of success with treatment. Refer to the treatment section for more information.
source - Impact booklet, produced by Hepatitis C Victoria, June 2008