Background

  • Gout and pseudogout are the most common crystal-induced inflammatory arthropathies. Crystals of urate (gout) and calcium pyrophosphate (pseudogout) are deposited within joints resulting in an immune response. 
  • Clinical features: Acute onset, red, hot and swollen joints which can be severely painful

 

Gout

Pathophysiology

  • Inflammatory arthritis – microcrystal synovitis
  • Cause: Deposition of monosodium urate monohydrate within the synovium (as a result of hyperuricaemia)
  • Most common joint affected: 1st metatarsophalangeal joint (70%)

Clinical features

  • Acute, severe pain with redness and swelling most often of the metatarsophalangeal joints
  • Other joints commonly affected include midfoot, elbow, ankle, knee
  • Gouty tophi - hard, cutaneous nodules composed of sodium urate crystals - ears, achilles, hands

Risk factors

Factors which increase urate synthesis ( high cell turnover), or impair urate excretion. 

  • Drugs: Aspirin, thiazides, furosemide, cytotoxics, ciclosporin
  • Comorbidities: CKD, psoriasis 

Investigations

  • NICE CKS states:
    • 1st line: Measure the serum urate level - if  360 or more, this confirms the diagnosis
    • 2nd line: “if the diagnosis remains uncertain” - arrange investigations in secondary care including:
      • Joint aspiration for polarised light microscopy - Needle shaped, negatively birefringent crystals

Acute Management

  • 1st Line: NSAID (naproxen) OR  colchicine (esp. if renal impairment) OR a short course of oral corticosteroids
    • Colchicine – common side effects = diarrhoea
    • NSAID – should be prescribed with PPI, avoid in renal disease
    • Prednisolone can be used as an alternative - but this is off label - 30-35 mg OD for 3-5 days 

Chronic Management - Urate Lowering Therapy

  • Urate lowering therapy (ULT) should be considered after the first attack of (2-4 weeks after acute attack). 
  • Target: Aim for a target urate of < 360 (or < 300 if recurrent flares/gouty tophi) and titrate dose of chosen ULT until target reached. 
  • 1st Line: Offer Allopurinol OR  febuxostat first line taking into account comorbidities
    • Allopurinol is preferred if history of cardiovascular disease
    • Co-prescribe colchicine (or NSAID) when commencing ULT

  

Allopurinol

  • Mechanism of action: xanthine oxidase inhibitor
  • Starting dose approx. 100mg OD 
  • This should be titrated until uric acid level < 300 umol/L

  

Febuxostat

  • Mechanism of action: xanthine oxidase inhibitor
  • Ensure LFTs are checked before commencing treatment


 

 

Pseudogout

Pathophysiology

  • Inflammatory arthritis – microcrystal synovitis caused by the deposition of calcium pyrophosphate dihydrate crystals
  • Most commonly affects large joints: Knees, ankles, elbows, wrists 

Risk factors

  • Increasing age
  • Haemochromatosis

Investigations

  • Microscopy:
    • Rhomboid shape, positively birefringent crystals
  • X-ray
    • Chondrocalcinosis / calcification of cartilage/meniscus 

Management

  • Manage with NSAIDs or steroids (PO/IA/IM)

  

References and Further Reading 

  

NICE CKS. Gout [June 2022]. Available at URL: https://cks.nice.org.uk/topics/gout/management/