rheumatoid arthritis (RA) can be difficult to diagnose because many conditions cause joint stiffness and inflammation. Your doctor will do a physical examination, checking your joints to see if they are swollen and to find out how easily they move. It is very important to tell your doctor about all of your symptoms, not just the ones you think are important.
If your doctor thinks you have RA they may refer you to a specialist called a 'rheumatologist'. A rheumatologist can diagnose this disease and ensure you receive the right treatment. If you have RA and have not yet seen a rheumatologist, you can ask your doctor for a referral.
After conducting a physical examination and consulting your medical history, your doctor may carry out a series of tests which may help to confirm the diagnosis, or they may refer you at the same time as requesting tests. Tests that you may have are outlined below.
No blood test can definitively diagnose RA. While a number of tests can indicate to your doctor that you may have developed the condition, they will not necessarily prove or rule out the diagnosis. If you have persistent joint inflammation, you will need to see a rheumatologist.
Erythrocyte sedimentation rate (ESR)
In an ESR test, a sample of your red blood cells is placed into a test tube of liquid. The cells are then timed to see how fast they fall to the bottom of the tube (measured in millimetres per hour). If they are sinking faster than usual, you may have an inflammatory condition, such as RA.
C-reactive protein (CRP)
A CRP test can indicate if there is inflammation anywhere in the body by checking how much CRP is present in your blood. CRP is produced by the liver. If there is more CRP than usual, there is inflammation in your body.
Full blood count
The full blood count will measure your red cells to rule out anaemia. Anaemia is a condition where the blood is unable to carry enough oxygen, due to a lack of blood cells. Eight out of ten people with RA have anaemia. However, anaemia can have many causes, including a lack of iron in your diet. Therefore, having anaemia does not prove that you have RA.
This blood test checks to see if a specific antibody, known as the 'rheumatoid factor', is present in your blood. This antibody is present in eight out of ten people with RA. However, it cannot always be detected in the early stages of the condition. The antibody is also found in 1 in 20 people who do not have RA, so this test cannot confirm RA. If it is negative, another antibody test (for anti-CCP) may be done, which is more specific for the disease.
X-rays of your joints can help differentiate between different types of arthritis. A series of X-rays can also help show how your condition is progressing. A chest X-ray may also be taken as both the disease and certain treatments (such as methotrexate) can affect the chest.
Musculoskeletal ultrasound may be used in the clinic to confirm the presence, distribution and severity of inflammation and joint damage.
Magnetic resonance imaging (MRI) scans can help show what damage has been done to a joint.
Source: NHS Choices, UK (Diagnosing rheumatoid arthritis)
Last reviewed: July 2015