Gout or Pseudogout
Gout is inflammation in the joint that occurs when the level of urate (a breakdown product of various chemical processes in the body) in the blood is too high and urate crystals form in the joint. The base of the big toe is the joint most frequently involved. The crystals can also deposit in the skin (tophi) causing hard painless lumps. The tendency to have an elevated urate level is often inherited and caused by either under-excretion or over-production of urate. An acute attack is usually treated with anti-inflammatory drugs. Patients experiencing frequent attacks may be prescribed allopurinol which reduces the production of urate.
Pseudogout is similar to gout but the inflammation is caused by the deposition of calcium pyrophosphate crystals. The wrist and the knee are the commonest joints involved and it usually occurs in older people who have osteoarthritis or damaged joints. The treatment is similar to gout but allopurinol is not used.