How is RA diagnosed?
There is no single test for RA, and diagnosing it can be complicated. Your doctor will ask you about the difficulties you’ve been having. All of these are useful clues. Your doctor will examine your joints and skin, and test your muscle strength. A physical exam will look for signs such as warmth, swelling and pain in the joints.
It is important that if you think you might have RA, you are referred to a rheumatologist. Rheumatologists are experts in diagnosing and treating arthritis and other diseases that affect the joints, bones and muscles. Research shows that the sooner you start treatment for RA, the more effective that treatment is likely to be. Early intervention is critical to a good outcome so there should be no delay in referring you for assessment. The Irish Society for Rheumatology (ISR) recommends that a person going to their doctor with symptoms of RA should be seen within six weeks. Your GP can send in a National Early Inflammatory Arthritis Referral Form which is accepted by most rheumatology clinics in Ireland.
A DAS (Disease Activity Score) may be used by your healthcare team which measures the severity of your disease. It is calculated using two different measures: counting the number of tender and swollen joints (28 in total) and the number of circulating inflammatory markers.
It’s likely that your doctor will order a range of blood tests for you to help confirm RA. These blood tests will test for:
- Rheumatoid Factor – an antibody found in 80% of people with RA. For many, though, this antibody is not always present in the early stages of the disease.
- Anti CCP – another antibody found in 60-70% of people with RA. If you test positive for this, you are more likely to develop RA.
- Anaemia – your blood count.
- CRP & ESR – blood protein and cell levels that measure how much inflammation or disease activity there is in your body (This blood test might be done again after you start treatment to see how you’re responding).
Blood tests are useful in diagnosing RA, but some people will have no signs of it in their test results.
After your blood tests are completed, you may hear your doctor and other medical team members talk about ‘seropositive’ arthritis and ‘seronegative’ arthritis.
‘Seropositive’ arthritis means that your bloods tests showed you tested positive for CCP antibodies and a rheumatoid factor. This type of arthritis tends to be the more aggressive type of RA.
‘Seronegative’ arthritis means that your bloods tests do not have a positive rheumatoid factor or show CCP antibodies. This type of RA tends to be a little milder.
Your doctor may also send you for x-rays. In the early stage of RA, these x-rays may be normal. X-rays will only show any damage done to the joints, which, in the early stages, might be little or none. It’s good, though, to have these x-rays done as they can be used to compare with later x-rays to see how the disease is progressing. An ultrasound may also be carried out to access any joint damage.