The C-reactive protein (CPR) test is a blood test that checks for infection or inflammation in the body. It is used to detect the severity of inflammation or whether you are responding to treatment. It does not show where the inflammation is in your body.
What is being tested?
Levels of C-reactive protein (CRP) start to increase very soon after any inflammation or infection affects the body. CRP is made in the liver then released into the bloodstream.
Why would I need this test?
You might need this test if your doctor suspects that you have an infection or an illness related to inflammation (such as rheumatoid arthritis or inflammatory bowel disease). CRP can help confirm a diagnosis and assess how well treatment is going for these kinds of illnesses.
Sometimes CRP is tested if a pregnant woman has ruptured her membranes (broken her waters) early. CRP can indicate if there are any problems with the baby.
A special type of CRP called a high-sensitivity CRP (hs-CRP) can help determine the risk for heart disease.
How to prepare for this test
No preparation is needed for this test.
Understanding your results
A high CRP indicates that there is inflammation or an infection somewhere in your body. Other tests might be necessary to find out where or which specific illness is causing it.
If you are being treated for an infection or inflammation, CRP levels should decrease.
You should discuss the results with your doctor to understand what they mean specifically for you.
Visit Lab Tests Online website for more information about C-reactive protein testing.
Read our ‘Guide to blood testing’ to learn more about blood tests in general with information such as:
- what to consider before having the test
- what happens during a blood test
- results accuracy
- blood tests cost
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Last reviewed: June 2018