Gout

• Gout is a type of crystal arthropathy associated with chronically high blood uric acid levels.
• Urate crystals are deposited in the joint, causing it to become inflamed.
• Typical presentation:

  • Monoarticular
  • Acutely hot
  • Swollen
  • Painful
• The critical differential diagnosis for this presentation is septic arthritis.
• Gouty tophi = subcutaneous uric acid deposits typically seen on the hands, elbows and ears
• Risk factors:

  • Male
  • Family history
  • Obesity
  • High purine diet (meat and seafood)
  • Alcohol
  • Diuretics
  • Cardiovascular disease
  • Kidney disease
• The most commonly affected joints are:

  • The base of the big toe – the metatarsophalangeal joint (MTP joint)
  • The base of the thumb – the carpometacarpal joint (CMC joint)
  • Wrist
• Gout can also affect larger joints like the knee and ankle
• Diagnosis is usually made clinically, supported by a raised serum urate level on a blood test.
• Aspirated fluid:

  • Linear crystals (monosodium urate crystals)
  • Needle shaped and negatively birefringent of polarised light
  • Should be no bacterial growth
• X-ray of a joint affected by gout shows:

  • Maintained joint space (no loss of joint space)
  • Lytic lesions in the bone
  • Punched out erosions
  • Erosions can have sclerotic borders with overhanding edges
• Acute flare management:

  1. NSAIDs + PPI
  2. Colchicine (for those who cant take NSAID)
  3. Oral steroids
• Prophylaxis is with xanthine oxidase inhibitors that lower the uric acid levels:

  • Allopurinol
  • Febuxostat
  • If an acute attack reoccurs, these drugs are continues during the attack
• Prophylaxis is not started until weeks after an acute attack
• Lifestyle changes can reduce the risk of gout. This involves losing weight, staying hydrated and minimising the consumption of alcohol and purine-based food (e.g., meat and seafood).