A C-reactive protein test (CRP) is a blood test which measures the amount of a protein known as C-reactive protein in the blood. C-reactive protein measures general levels of inflammation in the body. Certain circumstances cause the CRP level to rise, which may make it misleading. These include physical exertion (exercise), the coil, pregnancy or obesity.
CRP tests are carried out for a number of reasons. Initially, a CRP test is carried out to check whether there is any infection in the body following surgery. CRP normally rises within 2 to 6 hours of an operation and then falls on the third day after the operation. If CRP levels remain elevated three days after the operation, this may be due to an infection.
To identify and keep track of infections and diseases causing inflammation, such as cancer of the lymph nodes (lymphoma), diseases of the immune system (such as lupus), swelling of blood vessels in the head and neck, painful swelling of the tissues lining the joints (rheumatoid arthritis), swelling and bleeding of the intestines (inflammatory bowel disease) or bone infection (osteomyelitis). To check how well treatments are working, such as treatment for cancer or infection. CRP levels rise quickly and then quickly return to normal if the patient responds to treatment.