C-reactive protein (CRP) is a substance produced by the liver in response to inflammation. It is part of the body’s immune response and is classified as an acute-phase protein, meaning its levels in the blood increase in response to inflammation. CRP is named for its ability to precipitate the C-polysaccharide of pneumococcus, a type of bacteria, which was how it was first discovered.

The primary function of CRP is to bind to phosphocholine expressed on the surface of dead or dying cells and some types of bacteria, which activates the complement system, a part of the immune system that enhances the ability to clear microbes and damaged cells. This process helps to promote phagocytosis by macrophages, which are cells that engulf and digest cellular debris and pathogens.

Clinically, CRP is used as a biomarker to assess inflammation and is measured through a blood test. Elevated levels of CRP are not specific to any one disease but indicate that there is inflammation in the body. This can be due to a variety of conditions, including infections, chronic inflammatory diseases such as rheumatoid arthritis, and acute conditions like a heart attack.

In the context of cardiovascular health, CRP levels are often measured to assess the risk of cardiovascular disease. High-sensitivity CRP (hs-CRP) tests can detect lower levels of CRP and are used to evaluate the risk of heart disease. Studies have shown that elevated CRP levels are associated with an increased risk of heart attacks, strokes, and peripheral arterial disease, even in individuals with normal cholesterol levels.

CRP levels can also be used to monitor the effectiveness of treatment for inflammatory conditions. For example, in patients with rheumatoid arthritis, decreasing CRP levels can indicate that treatment is reducing inflammation.

It is important to note that while CRP is a useful marker of inflammation, it is nonspecific. This means that while it can indicate the presence of inflammation, it does not pinpoint the exact cause. Therefore, elevated CRP levels should be interpreted in conjunction with other clinical findings and diagnostic tests.

In summary, C-reactive protein is a key marker used in medicine to detect and monitor inflammation. Its measurement provides valuable information about the presence and intensity of inflammation, aiding in the diagnosis and management of various conditions, particularly those related to cardiovascular health and chronic inflammatory diseases.