What is a c-reactive (CRP) protein test?A c-reactive protein test measures the level of c-reactive protein (CRP) in a sample of your blood. CRP is a protein that your liver makes. Normally, you have low levels of c-reactive protein in your blood. Your liver releases more CRP into your bloodstream if you have inflammation in your body. High levels of CRP may mean you have a serious health condition that causes inflammation.Inflammation is your body's way of protecting your tissues and helping them heal from an injury, infection, or other disease. Inflammation can be acute (sudden) and temporary. This type of inflammation is usually helpful. For example, if you cut your skin, it may turn red, swell, and hurt for a few days. Those are signs of inflammation. Inflammation can also happen inside your body.If inflammation lasts too long, it can damage healthy tissues. This is called chronic (long-term) inflammation. Chronic infections, certain autoimmune disorders, and other diseases can caus...