How is reactive arthritis diagnosed?
Reactive arthritis can usually be told apart from other arthritic conditions because of the link to an earlier infection. Your doctor will therefore probably ask about your recent health and sexual activity if reactive arthritis is suspected.
Doctors usually diagnose reactive arthritis on the basis of one or more of the following signs:
- you suddenly develop symptoms just after an infection – but the infection may have been so mild that you didn’t notice it, so sometimes doctors diagnose reactive arthritis even when there’s no definite history of infection
- all tests for other forms of arthritis (such as rheumatoid arthritis) are negative
- the arthritis is accompanied by symptoms very typical of reactive arthritis, such as rash over the palms or soles or red painful eyes.
What tests are there?
There’s no specific test for reactive arthritis, but the following may be used to confirm a diagnosis or rule out other causes of the symptoms:
- a stool sample, or swabs taken from your throat, penis or vagina, which can be tested for signs of inflammation or infection
- blood tests to check for levels of inflammation and sometimes to test for the HLA-B27 gene.
Blood tests can also be used to test for antibodies associated with other forms of arthritis. These antibodies include rheumatoid factor and anti-nuclear antibody.
If your eyes are sore and red you may be examined by an eye specialist (ophthalmologist) in order to check that it isn’t a serious inflammation of the eye, known as iritis. This is different from conjunctivitis (which is the most common cause of a painful red eye). Iritis is inflammation of the coloured part of the eye (the iris), whereas conjunctivitis is inflammation of the white of the eye.