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C-Reactive Protein (Blood)Proteína C reactiva (en suero)

C-Reactive Protein (Blood)

Does this test have other names?


What is this test?

The C-reactive protein (CRP) test is used to find swelling and infection in your body. It does this by measuring the amount of CRP in your blood. CRP is a protein made by the liver and sent into the bloodstream. Blood levels may be higher when you have swelling (inflammation) or an infection. Because CRP levels often go up before you have symptoms of pain or fever and drop down as you recover, the CRP test is especially useful for tracking infections. 

Because C-reactive protein is part of the immune system, your levels of it rise whenever you have swelling in your body. In fact swelling can trigger a large jump in CRP. But the test doesn't show where the swelling is or what is causing it.


Why do I need this test?

You may need this test if your health care provider thinks you have an infection. This may be osteomyelitis, which involves bone. Or it may be a potentially life-threatening condition called sepsis or blood poisoning.





What other tests might I have along with this test?

Because the CRP test tells you only if you have swelling and doesn't pinpoint what is causing it, your health care provider will likely order more tests. These may include:

  • Erythrocyte sedimentation rate, or ESR, test. Like the CRP, this test measures inflammation. It's not as sensitive as the CRP, but it's easy to do and gives additional information, so many doctors will order it at the same time.




What do my test results mean?



How is this test done? 


Does this test pose any risks?


What might affect my test results?


Medicines such as nonsteroidal anti-inflammatory drugs, aspirin, and steroids can cause your CRP levels to be lower than normal. 

How do I get ready for this test?

You don’t need to prepare for this test. Be sure your health care provider knows about all medicines, herbs, and supplements you are taking. This includes medicines that don’t need a prescription and any illicit drugs you may use.