68. Gout

Gout is a metabolic disorder secondary to hyperuricemia in which crystals of monosodium urate cause an acute inflammatory response in joints or a foreign body response in the soft tissues or bones. The most common site is the metacarpophalangeal joint of the great toe and the knee. Soft tissue deposits of urate crystals, tophi, occur. It may present clinically with acute onset of severe pain of a joint or as a chronic joint problem. In bones, radiographs may be normal and later present periarticular erosions. With polarized light, the urate crystals in tophi or synovial fluid appear anisotropic. Prognosis in treated disease is generally good. Uricosuric drugs and allopurinol are used for treatment.