What It Is
C-reactive protein, commonly abbreviated as CRP, is a blood test that measures a protein produced by the liver in response to inflammation somewhere in the body.
What It Checks
The test measures the concentration of CRP circulating in the blood. CRP levels rise when there's inflammation present in the body, from a wide range of possible causes, and fall again once the underlying inflammatory process settles, making it a general, non-specific marker of inflammatory activity rather than a test that identifies a particular cause on its own.
Why It's Used
CRP testing is commonly used as a general indicator of inflammation in the body, and is often used alongside other tests and clinical information to help build a broader picture of what might be happening, given that CRP alone doesn't point to a specific condition.
How It's Done
A CRP test requires a standard blood sample, typically drawn from a vein in the arm, in the same way as most routine blood tests. No special preparation is generally required beforehand.
Background
C-reactive protein was first identified in the 1930s, named for its ability to react with a specific component of certain bacteria in laboratory conditions, which is how researchers first detected its presence. Its broader significance as a marker of inflammation throughout the body became better understood over the following decades, and increasingly sensitive laboratory methods for measuring it were developed over time, making CRP testing a widely available and commonly used general inflammatory marker in healthcare today.