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A C-reactive protein (CRP) test is a blood test that measures the amount of a protein called C-reactive protein in your blood. C-reactive protein measures general levels of inflammation in your body.
High levels of CRP are caused by infections and many long-term diseases. But a CRP test cannot show where the inflammation is located or what is causing it. Other tests are needed to find the cause and location of the inflammation.
A C-reactive protein (CRP) test is done to:
There is no special preparation for a C-reactive protein (CRP) test. You might be asked to not eat or drink for a few hours before the test.
Tell your doctor all of the medicines you are taking because some medicines can affect the results.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form .
The health professional taking a sample of your blood will:
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having a blood sample taken from a vein.
A C-reactive protein (CRP) test is a blood test that measures the amount of a protein called C-reactive protein in your blood.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are usually available within 24 hours.
Less than 1.0 milligram per decilitre (mg/dL) or less than 10 milligrams per litre (mg/L)
Any condition that results in sudden or severe inflammation may increase your CRP levels.
Some medicines may decrease your CRP levels.
Many conditions can change CRP levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.
You may not be able to have the test, or the results may not be helpful, if:
C-reactive protein can be found with this test within a few hours of an inflammation response. So a higher-than-normal CRP level shows a current inflammation. The CRP level drops back to normal when the inflammation goes away.
CitationsFischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Current as of: August 31, 2020
Author: Healthwise StaffMedical Review: Adam Husney MD - Family MedicineBrian D. O'Brien MD - Internal MedicineE. Gregory Thompson MD - Internal MedicineMartin J. Gabica MD - Family MedicineStephen Fort MD, MRCP, FRCPC - Interventional Cardiology
Current as of: August 31, 2020
Author: Healthwise Staff
Medical Review:Adam Husney MD - Family Medicine & Brian D. O'Brien MD - Internal Medicine & E. Gregory Thompson MD - Internal Medicine & Martin J. Gabica MD - Family Medicine & Stephen Fort MD, MRCP, FRCPC - Interventional Cardiology
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