When arriving at a diagnosis doctors may take the following factors into account:
- physical examination to establish which joints are affected;
- medical history- gout is more likely if arthritis first appears in the big toe;
- the speed of onset of the pain and swelling, symptoms that take days or weeks rather than hours to develop are unlikely to be indicative of
gout;
- abnormal enlargements in joints which had previously been affected by previous injury or osteoarthritis are possible signs of gout;
- synovial fluid is taken from the joint and tested to see if it contains urate crystals. Examination of the synovial fluid is the most accurate method of
diagnosing gout. The doctor uses a needle attached to a syringe and draws out fluid from the affected joint. This process is called aspiration, local
anasthesia is not used as this can reduce the effectiveness of the procedure. Aspiration sometimes eases symptoms by reducing swelling and pressure on
the tissue surrounding the joint;
- blood is taken to check the levels of uric acid in the blood. A low level of uric acid in the blood makes a diagnosis of gout less likely whilst
a very high level will make a diagnosis more probable.
It is possible to confuse gout with pseudogout which is a condition caused by deposits of calcium pyrophosphate dihydrate crystals in the joints. The
main differences between the two conditions are:
- the first attack usually strikes the knee. Other joints affected are the shoulders, wrists and ankles. In two thirds of cases more than one joints is affected
during a first attack. The small joints in the fingers and toes are not normally affected;
- the symptoms of pseudogout take days rather than hours to develop;
- pseudogout is more likely to develop in older people, particularly those with a history of osteoarthrits.
