Crystal induced arthritis: gout and pseudogout.

Intrasynovial deposits of monourate crystals in the presence of serum hyperuricaemia, and calcium pyrophosphate dihydrate (CPPD) crystals, are responsible for gout and pseudogout respectively. Identification of these by synovial fluid analysis is described. The clinical features, minimum investigations, history-taking, management and drug regimes of gout and pseudogout are discussed. Periodic review of the patient is stressed. Other intrasynovial crystals are briefly outlined.