Form of arthritis caused by the deposition of monosodium urate crystals in and around the joints leading to an acute inflammatory response

Aetiology

• Usually due to high serum uric acid levels (hyperuricaemia)

Causes of hyperuricaemia

Increased urate production

• High dietary purine intake (red meat, seafood, corn syrup)
• Alcohol
• Inherited enzyme defects
  • Usually idiopathic - 90% unknown enzyme deficiency
  • HGPRT enzyme deficiency impaires purine nucleotide salvage pathway → degraded to urate
• Myeloproliferative/lymphoproliferative disorders
• Psoriasis
• Haemolytic disorders

Reduced urate excretion

• Chronic renal impairement
• Volume depletion e.g. heart failure
• Hypothyroidism
• Diuretics
• Cytotoxics e.g. cyclosporin

Risk factors

• Age - rare under 20, decreases after age 80
• More common in men than women