Gout develops when monosodium urate crystals (MSU) precipitate in a joint, characteristically causing pain, swelling and erythema. The incidence of gout, in the UK, is 13 per 10,000 patient years. It increases with age to a maximal incidence in patients aged 65-84 years. Gout is approximately twice as common in men. Oestrogenic hormones are thought to have a mild uricosuric effect in premenopausal women. [With external links to the evidence base]