C reactive protein (CRP) and rheumatoid arthritis are closely linked in most patients suffering from rheumatoid arthritis. The presence of CRP in a patient's bloodstream can alert doctors to the possibility that the patient has this disease, though not all patients with rheumatoid arthritis will test positive for CRP. Though CRP can be indicative of other problems, the presence of this protein along with other symptoms of rheumatoid arthritis can be a strong indicator that a patient has the disease. Rheumatoid arthritis is often difficult for doctors to diagnose because so many of the symptoms mimic those of other disorders, so a test to determine the presence of CRP is one way to narrow down the possible causes of a patient's symptoms.
Doctors have been aware of the connection between CRP and rheumatoid arthritis since the 1980s. This protein was discovered in the 1930s, when it was discovered that the presence of this protein in a patient's blood stream indicates that there is inflammation somewhere in the body. While tests of CRP levels cannot be used to indicate where or how severe the inflammation is, the test can help doctors diagnose rheumatoid arthritis. Patients with mild cases of this disease may not have visible swelling in the joints, but the presence of CRP can confirm the presence of inflammation.
CRP can indicate any type of swelling, so when making a connection between the presence of CRP and rheumatoid arthritis, doctors need to examine a number of other factors. Patients with rheumatoid arthritis often test positive for certain antibodies, which, when present along with CRP, can indicate the possibility of this disease. Though CRP can indicate rheumatoid arthritis, it may also be present in patients who are overweight, so doctors will take this into account when examining the levels of this protein in the patient's bloodstream. CRP and rheumatoid arthritis are not linked so closely that the presence of one positively indicates the presence of the other.
Levels of CRP in a patient's bloodstream can also be used to determine how effective treatments for rheumatoid arthritis are for an individual patient. When examining this connection between CRP and rheumatoid arthritis, doctors will periodically test levels of CRP in a patient's bloodstream in order to determine whether inflammation is decreasing. A drop in CRP indicates that a particular rheumatoid arthritis treatment may be effective, while an increase or no change in CRP levels may indicate that the disease is continuing to progress, even if the patient's symptoms have improved.