The CRP test, or C-reactive protein test, measures the level of CRP in the blood. CRP is a substance produced by the liver in response to inflammation. High levels of CRP can indicate the presence of inflammatory conditions, infections, or chronic diseases, helping doctors assess a patient's health status. The test is simple and involves drawing a small amount of blood, which is then analyzed in a laboratory. Results can help guide treatment decisions and monitor the effectiveness of therapies for conditions like rheumatoid arthritis or inflammatory bowel disease.