🔑 Key Learning

  • Gout and pseudogout are crystal-induced inflammatory arthropathies, presenting with sudden onset of red, hot, swollen joints.
    • Gout: Caused by monosodium urate crystals, commonly affects the 1st MTP joint.
    • Pseudogout: Caused by calcium pyrophosphate crystals, most often affects large joints like the knee.
  • Diagnosis is clinical but can be confirmed with joint aspiration.
    • Negatively birefringent needle shaped crystals = gout 
  • Management includes NSAIDs, colchicine, or corticosteroids acutely, and urate-lowering therapy long-term in gout.

💎 Gout

🧬 Pathophysiology

  • Deposition of monosodium urate crystals in joints due to hyperuricaemia → intense inflammatory response.
  • Commonest site: 1st MTP joint (~70%).

👀 Clinical Features

  • Acute, severe pain, swelling, redness over affected joint.
  • Common sites: MTP joint, ankle, knee, elbow, midfoot.
  • Gouty tophi: Firm, painless nodules (ears, hands, Achilles tendon).
Gout. Classically affects 1st MTP. Gonzosft, CC BY 3.0 DE via Wikimedia Commons
Tophaceous gout affecting the right great toe and finger interphalangeal joints. Note the asymmetrical swelling and yellow-white discolouration. Arthritis Research UK Primary Care Centre, Primary Care Sciences, Keele University, Keele, UK. e.roddy@cphc.keele.ac.uk, CC BY 2.0, , via Wikimedia Commons

⚠️ Risk Factors

  • Drugs: Thiazides, furosemide, aspirin, cytotoxics, ciclosporin.
  • Conditions: CKD, psoriasis, obesity, high purine diet, alcohol.

🧪 Investigations

  • 1st Line: Serum urate > 360 µmol/L confirms diagnosis (but can be normal during acute attack).
  • 2nd Line: Joint aspiration for negatively birefringent, needle-shaped crystals under polarised light.
  • U&E: Assess for renal function.
  • X-ray (chronic): May show joint erosions, soft tissue tophi.

💊 Acute Management

  • NICE advises any of the following, acording to patient's co-morbidities, preferences and regular medications:
    • NSAID - naproxen, ibuprofen 
      • Consider co-presciribing PPI.
      • Avoid in renal disease, peptic ulcer disease etc. 
    • Colchicine. 
      • Adverse effect: Diarrhoea/GI upset
    • PO prednisolone 30-35 mg once a day for 3-5 days. (off-label)
  • If 1st line approach not tolerated or contraindicated, consider IM/IA corticosteroid

💊 Chronic Management – Urate-Lowering Therapy (ULT)

  • Start 2–4 weeks after acute flare (not during).
  • Target serum urate:  < 300 
  • 1st Line: Allopurinol or febuxostat.
    • Allopurinol: Xanthine oxidase inhibitor. Start 100 mg OD, titrate.
    • Febuxostat: Alternative. Check LFTs before starting.
  • Co-prescribe colchicine (or NSAID) as prophylaxis during ULT initiation.

💎 Pseudogout (CPPD – Calcium Pyrophosphate Deposition)

🧬 Pathophysiology

  • Caused by deposition of calcium pyrophosphate dihydrate crystals in the joint.
  • Triggers acute inflammation and joint swelling.

👀 Clinical Features

  • Acute pain, swelling, and warmth in large joints: Knee, wrist, ankle, elbow.
  • May mimic septic arthritis or gout.

⚠️ Risk Factors

  • Increasing age
  • Haemochromatosis
  • Hyperparathyroidism, hypomagnesaemia, hypothyroidism

🧪 Investigations

  • Synovial fluid analysis: Positively birefringent, rhomboid crystals.
  • X-ray: Chondrocalcinosis (cartilage calcification), especially in knees or wrists.

💊 Management

  • NSAIDs: 1st line in acute flare.
  • Oral corticosteroids: If NSAIDs contraindicated.
  • Intra-articular steroids: If single joint involved.
  • Consider investigation and treatment of underlying metabolic causes.

📝 Exam Clues & Clinchers

  • 1st MTP joint pain, redness, swelling → Gout
  • Negative birefringent needle crystals → Gout
  • Knee pain, chondrocalcinosis, rhomboid positive birefringent crystals → Pseudogout
  • Colchicine SE → diarrhoea
  • Gout often linked to thazides, diuretics and CKD; pseudogout to elderly + haemochromatosis

🔗 Useful Links and References