A C-reactive protein (CRP) test is done to:
- Check for infection after surgery. CRP levels normally rise within 2 to 6 hours of surgery and then go down by the third day after surgery. If CRP levels stay elevated 3 days after surgery, an infection may be present.
- Identify and keep track of infections and diseases that cause inflammation, such as:
- Cancer of the lymph nodes ( lymphoma ).
- Diseases of the immune system, such as lupus.
- Painful swelling of the blood vessels in the head and neck ( giant cell arteritis ).
- Painful swelling of the tissues that line the joints ( rheumatoid arthritis ).
- Swelling and bleeding of the intestines ( inflammatory bowel disease ).
- Infection of a bone ( osteomyelitis ).
- Check to see how well treatment is working, such as treatment for cancer or for an infection. CRP levels go up quickly and then become normal quickly if you are responding to treatment measures.
A special type of CRP test, the high-sensitivity CRP test (hs-CRP), may be done to find out if you have an increased chance of having a sudden heart problem, such as a heart attack. Inflammation can damage the inner lining of the arteries and make having a heart attack more likely. But the connection between high CRP levels and heart attack risk is not understood very well.
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