A C-reactive protein test measures the amount of CRP in your blood. CRP levels can reflect the presence and severity of inflammation in your body. CRP is a protein produced by the liver. When bacteria or other cellular invaders threaten the body, the liver releases CRP into the bloodstream to help organize the body’s defenses. This early response is called an acute phase response. It is also referred to as inflammation or an inflammatory response. The acute phase response also can occur in chronic conditions, including some autoimmune diseases. Fresh serum is the recommended specimen