How significant is raised uric acid?
Q During a routine review the practice nurse requested a uric acid and it was marginally raised. The patient hadn't had an episode of gout for several years. How should asymptomatic raised uric acid be managed?
A The main causes of hyperuricaemia are: drug induced, increased cell turnover (such as lymphoma leukaemiapsoriasis) and reduced excretion. It is associated with hypertension, hyperlipidaemia and dehydration. There is also a theoretical risk with low carbohydrate diets, due to their higher protein content.
A raised blood urate with no symptoms does not mean a patient will inevitably get gout. Risk factors should be looked for and diet/therapy modified if need be. Drug therapy is not appropriate unless there are concerns over uric acid stones, for example in renal failure.
I would not start allopurinol unless a patient was getting repeated attacks over a short period. Intermittent attacks can be treated with NSAIDs and lifestyle advice. Colchicine can be used for acute attacks if a patient is intolerant of NSAIDs; they can cause diarrhoea/abdominal cramps in some people and should not generally be used for prophylaxis.
It is sometimes said diagnosis of gout demands the joint should be aspirated and the crystals looked at under a microscope. I think a clinical diagnosis of gout is often good enough, especially if it is classical and the history and lifestyle factors fit. Then joint aspiration is not needed. Getting fluid from the big toe can be difficult.
Problems arise when the features are atypical and may be due to other causes, such as infection. Then it is important to aspirate the joint (most commonly the knee) and look for crystals, and also to culture for bacterial growth.
In these cases and if there is a suspicion about sepsis, aspiration and examination of joint fluid is invaluable.
Dr Inam Haq is educational research fellow at the Academic Centre for Medical Research, London