Gout

Gout is a form of microcrystal synovitis caused by the deposition of monosodium urate monohydrate in the synovium. It is caused by chronic hyperuricaemia (uric acid > 450 µmol/l)

Predisposing Factors

Decreased excretion of uric acid (90%)

drugs*: diuretics
chronic kidney disease
lead toxicity

Increased production of uric acid (10%)

myeloproliferative/lymphoproliferative disorder
cytotoxic drugs
severe psoriasis

Lesch-Nyhan syndrome

hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) deficiency
x-linked recessive therefore only seen in boys
features: gout, renal failure, neurological deficits, learning difficulties, self-mutilation

*aspirin in a dose of 75-150mg is not thought to have a significant effect on plasma urate levels - the British Society for Rheumatology recommend it should be continued if required for cardiovascular prophylaxis

Features

Patients typically have episodes lasting several days when their gout flares and are often symptom-free between episodes. The acute episodes typically develop maximal intensity with 12 hours. The main features it presents with are:

pain: this is often very significant