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C-Reactive Protein

Also known as: CRP
Formal name: C-Reactive Protein
Related tests: High-sensitivity C-reactive protein (hs-CRP); Erythrocyte sedimentation rate (ESR)

The Test

How is it used?

The CRP test is useful in assessing patients with:

CRP may be used to screen apparently healthy people for the following conditions. However, in these cases, the more sensitive test hs-CRP will be ordered:

While the CRP test is not specific enough to diagnose a particular disease, it does serve as a general marker for infection and inflammation, thus alerting medical professionals that further testing and treatment may be necessary.

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When is it ordered?

Because CRP increases in severe cases of inflammation, the test is ordered when acute inflammation is a risk (such as from an infection after surgery) or suspected based on patient symptoms. It is also ordered to help evaluate conditions such as rheumatoid arthritis and lupus and is often repeated to determine whether treatment is effective. This is particularly useful for inflammation problems since CRP levels drop as inflammation subsides.

CRP also is used to monitor wound healing and to monitor patients who have surgical cuts (incisions), organ transplants, or burns as an early detection system for possible infections.

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What does the test result mean?

Looking for reference ranges?

A high or increasing amount of CRP in your blood suggests that you have an acute infection or inflammation.

If the CRP level in your blood drops, it means that you are getting better and inflammation is being reduced.

 

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Is there anything else I should know?

CRP levels can be elevated in the later stages of pregnancy as well as with use of birth control pills or hormone replacement therapy (i.e., estrogen). Higher levels of CRP have also been observed in the obese.

Another test to monitor inflammation is called the erythrocyte sedimentation rate (ESR). Both tests are elevated in the presence of inflammation; however, CRP appears and then disappears sooner than changes in the ESR. Thus, your CRP level may fall to normal if you have been treated successfully, such as for a flare-up of arthritis, but your ESR may still be abnormal for a while longer.

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