One of the challenges in the management of rheumatoid arthritis is getting to the diagnosis of the disease. There is not a single blood test or an X-ray that can help make this diagnosis. There are multiple tests a doctor could perform to help make the diagnosis, but the most important step is a good examination by a doctor, particularly a rheumatologist.
How Rheumatoid Arthritis is Diagnosed
Rheumatoid arthritis is a clinical diagnosis, where a clinician examines your joints to identify the signs of inflammation. These signs may include swelling, redness, and warmth over affected joints. There are further tests, such as blood tests and X-rays, to help support the diagnosis.
Rheumatoid Factor Tests
Blood tests may also be used to estimate the prognosis of future joint damage. These blood tests help identify the signs of auto-immunity, one of the main features of rheumatoid arthritis–the body’s immune system is attacking the joint tissues. One way to understand such auto-immunity is the presence of abnormal proteins in the blood tests. Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) are two such tests. Presence of these factors also indicate a more severe disease which could increase the risk of permanent joint damage. Other blood tests which help in understanding the degree of inflammation in the body and help gauge effectiveness of treatment include erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).
Limitations of Blood Tests in Rheumatoid Arthritis
A longstanding frustration for doctors trying to diagnose rheumatoid arthritis by blood test is that there is no one test that could help make the diagnosis. RF and CCP tests are good indicators for rheumatoid arthritis, but there are patients who have signs and symptoms but test negative for RF and CCP. This is referred to as sero-negative rheumatoid arthritis. For this reason, rheumatologists will rarely content themselves with only blood tests or X-rays. Instead, they perform a thorough clinical examination to establish the diagnosis. They may order further testing to understand the specific manifestation of the disease in the patient and estimate the long-term risk of joint damage. It is worth noting that RF could be seen in other medical conditions (infections, lupus, tuberculosis) as well.
Conclusion
The best test for the diagnosis of rheumatoid arthritis is a good clinical examination by an experienced clinician. Blood tests (RF, CCP) support the diagnosis and characterize severe disease that could lead to joint damage. Markers of inflammation (ESR, CRP) help to evaluate treatment effectiveness.
Written by Shlomo Witty
