C-reactive protein (CRP) is an annular, pentameric protein found in blood plasma, whose levels rise in response to inflammation. It is an acute-phase protein of hepatic origin that increases following interleukin-6 secretion by macrophages and T cells.

CRP is used mainly as a marker of inflammation. The level of C-reactive protein (CRP), which can be measured in human blood, increases when there's inflammation in patient’s body.  It is not a specific test. That means it can reveal that you have inflammation somewhere in your body, but it cannot pinpoint the exact location. Measuring and charting CRP values can prove useful in determining disease progress or the effectiveness of treatments.

A high-sensitivity C-reactive protein (hs-CRP) test, which is more sensitive than a standard test, also can be used to evaluate the risk of developing coronary artery disease, a condition in which the arteries of your heart are narrowed.