Diagnosis and management of gout

Some diseases and drug treatments can lead to gout, but it can be easily treated, says Dr Alison Glenesk.

Gout, often portrayed as affecting only obese, meat-eating, port-drinking men, is a rather low-profile condition. There is no SIGN or NICE guideline associated with it, and it is not mentioned in the GMS contract.

Gout is caused when urate crystals form in joints, producing an inflammatory response.

Classically, it affects the metacarpophalangeal joint of the big toe, but it can occur in any peripheral joint.

It usually resolves after 10 days if untreated, and may not recur for months or even years. Sometimes attacks occur more frequently and chronic gout can cause permanent joint damage.

Patients with chronic gout may develop tophi. These are painless nodules of urate that form in the extremities.

Risk factors
The prevalence of gout in the UK is just over 1 per cent. It is more common in men than women, and is very uncommon in pre-menopausal women. However, incidence increases with age in both sexes.

Obesity, beer-drinking and a high intake of purine-rich foods, including meat and fish, are risk factors for gout. There is also a genetic component.

Some drugs, including diuretics and low-dosage salicylates, can increase the risk of gout by raising serum urate concentrations. Malignant diseases such as leukaemia and haemolytic anaemia can cause gout by increasing purine turnover.

Some very common diseases, such as hypertension, hypothyroidism, and chronic renal disease also cause gout by reducing purine excretion.

Diagnosis
Patients with gout have severe pain, often of sudden onset. On examination, they have severe joint tenderness, with a characteristic non-demarcated pink discoloration.

A blood test can be used to confirm a clinical suspicion of gout. Generally, the serum urate concentration needs to be at least 0.42mmol/l for gout to develop.

The definitive diagnostic test for gout is joint aspiration to look for urate crystals. This is not a popular procedure as it can be extremely painful; gout is usually treated on the basis of a clinical diagnosis.

The important differential diagnosis is infection, particularly septic arthritis. These patients will have blood test results very different from those of a patient with gout and should be referred immediately.

Treatment
An acute attack of gout can be treated using symptomatic measures such as rest, elevation of the affected area and application of ice.

However, NSAIDs are the mainstay of gout treatment in the UK. Indometacin is most commonly used, but other drugs including diclofenac have been successful.

Colchicine can be used when NSAIDs are contraindicated. However, its usefulness is limited by side-effects, including diarrhoea and vomiting, particularly common at higher dosages.

Short courses of steroids are also safe and effective for the treatment of gout.

Opiate drugs may be required if other treatments are contraindicated or ineffective. But they are rarely used in primary care for this purpose.

Recurrent gout
Risk-reduction measures such as reduction of alcohol consumption should be advised. The patient's medication should be reviewed to look for drugs that can cause hyperuricaemia.

Allopurinol is the drug of choice for the treatment of recurrent gout. It is a xanthine oxidase inhibitor that reduces the production of urate.

It should not be started during an acute attack as it can cause rebound hyperuricaemia. For the same reason, an NSAID or colchicine should be co-prescribed for at least one month. Serum urate levels should be checked within six months of starting the drug, with the aim of keeping them under 0.36mmol/l.

Allopurinol should not be used to treat patients with asymptomatic hyperuricaemia except in cases of malignancy, and where the serum urate level is extremely high (0.8mmol/l).

  Gout treatment
  Acute gout:
- Rest and elevation of the affected joint.
- NSAID treatment.
- Colchicine.
- Steroids.
- Opiates.
  Recurrent gout:
- Risk factor modification (weight loss and reduced alcohol consumption)
- Allopurinol.

Dr Glenesk is a GP trainer in Aberdeen.

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