What is a C-Reactive Protein Blood Test?
C-reactive protein, or CRP, is a protein produced by the liver that serves as a marker for inflammation. CRP levels rise when there is active inflammation somewhere in the body, but it doesn't indicate where or what's causing it.
An elevated CRP level can come from an infection or a disease that causes inflammation such as certain types of arthritis, autoimmune diseases, tuberculosis, cancer, inflammatory bowel disease, among others. Generally, doctors order this test when they suspect one of these conditions.
There are other situations where a doctor might order a C-reactive protein test. Since an elevated CRP level indicates inflammation, a level may be drawn to monitor the course of an infection or an inflammatory disease. For example, people who have inflammatory bowel disease frequently have an elevated CRP when they’re having an exacerbation. Drawing serial CRP levels would allow a doctor to follow the course of their disease and see if the treatment is working - since levels should go down as the inflammation subsides.
A C-reactive protein blood test can also be used to look for a flare-up of an autoimmune or inflammatory disease.