How is Gout Diagnosed?

Joint aspiration Joint Aspiration

A definite diagnosis of gout is made by demonstrating the presence of uric acid crystals within a joint fluid that is taken from the joint. This procedure is called joint aspiration, which involves the withdrawal of fluid into a syringe through a needle that is placed within the joint.

As mentioned above, the first big toe joint is often affected first but it can be difficult to get a sample from such a small joint.

An experienced doctor can make a clinical diagnosis based on the underlying risk factors for gout, the clinical presentation, and blood tests, particularly when these demonstrate hyperuricaemia and an elevation of inflammatory markers such as ESR and CRP.

There is a caveat to this. It is not uncommon to see a normal blood uric acid level during an acute attack. Therefore, a normal blood uric acid level does not exclude gout and it should be tested again a few weeks after a recent attack of gout.

Dual energy CT scanning is a relatively new technology that has recently become available to evaluate for the presence of uric acid crystals in a joint.

Early data suggests it has high specificity (0.93) and moderate sensitivity (0.78) (1). This means that we can confidently conclude the presence of gout with a positive scan, but a negative scan does not exclude the condition.