PCR Tests Test
A PCR test checks for tiny amounts of genetic material from a germ or abnormal cell in your body. It can find infections early, even before you have symptoms.
What this test measures
PCR (polymerase chain reaction) tests measure small amounts of genetic material (DNA or RNA) from a pathogen or abnormal cells in a sample of blood, saliva, mucus, or tissue.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Frequently asked questions
What does PCR stand for?
PCR stands for polymerase chain reaction.
What kinds of samples are used for a PCR test?
Samples can include blood, saliva, mucus, or tissue.
Can a PCR test find a virus after I've recovered?
Yes, PCR tests can find pieces of a virus you had, even after you are no longer infected.
Why is PCR more sensitive than other tests?
PCR can detect disease when there is only a very small amount of pathogens in your body, because it amplifies the genetic material.
What is the difference between DNA and RNA in PCR tests?
DNA contains genetic information for development and growth, while RNA carries information copied from DNA. Some viruses use RNA instead of DNA.
Related lab tests
Sources
- MedlinePlus: PCR Tests — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.