Gout
Gout is caused by inflammation against monosodium urate (MSU) crystals. MSU crystals can accumulate in the body (often in and around joints) when certain physicochemical conditions lead to uric acid becoming poorly soluble and precipitating in the soft tissues. Uric acid is a breakdown product of cells in the body.
A high level of uric acid in the blood is termed 'hyperuricemia'. The greater the hyperuricemia the greater the risk of gout. Hyperuricemia is more likely when:
there is an excess of foods or drinks containing purines in diet (e.g. alcohol, shellfish, liver);
the body load of purines/cells/uric acid is high (in obesity);
with certain common medications (e.g. low dose aspirin and some diuretics);
uric acid cannot be excreted from the body (e.g. poor kidney function).
Also, the metabolic efficiency with which purines and uric acid are metabolised and excreted by the body is partly influenced by our genes, so the tendency to get gout can be partly inherited.
Gout typically causes explosive pain and swelling and often reddening of skin (an 'attack'!). Pain is often intense. Typical sites of gout attack include great toes, ankles, the whole foot, knee and sometimes hands and wrist structures. It's important to discriminate carefully between gout of the great toe and dactylitis caused by Psoriatic Arthritis (toe looks 'sausage-like' with the latter and is usually not reddened).
Gout is typically different in men and women. In women it is rare before the menopause and when it occurs, gout behaves less like ‘attacks’ and more like general inflammatory arthritis. In men gout can occur in the 30s and 40s but its more common in 50s and older.
Acute gout is treated with rest, elevation of the affected part, ice and strong prescription-strength non-steroidal anti-inflammatory (NSAID) painkillers and sometimes colchicine. Sometimes a short course of steroid tablets are used. Where there is recurrent acute gout or chronic gout arthritis the treatment strategy must involve: weight loss, dietary changes where relevant and the use of drugs to lower the uric acid (e.g. allopurinol or febuxostat). Doctors treating gout should try to get the uric acid level down to <300µmol/l with these treatments (a 'treat-to-target' approach) because with the uric acid below this blood concentration ('the target'), then gout attacks will be rare.
Links:
http://www.ukgoutsociety.org
2017 guidance on gout management is at BSR:
https://academic.oup.com/rheumatology/article-lookup/doi/10.1093/rheumatology/kex156
The Electronic Medicines Compendium. Information on allopurinol and febuxostat. Use the drug names in the search box then read the relevant ‘Patient Information’ document for the drug, at:
www.medicines.org.uk