Gout and Crystal-Associated Arthritis

Crystal-Associated Arthritis

• Gout
  • More common in males
  • Can occur in older men, but younger men can also be affected
  • Associated with ankylosing spondylitis in some cases
• Causes of Gout
  • Overproduction of uric acid
    • Acquired
    • Dietary factors (hematological, psoriatic, chemotherapy diseases)
    • Inherited
  • Underexcretion of uric acid
    • Renal (90%)
    • Combination of overproduction and underexcretion
  • Alcohol is a contributing factor
    • Uric acid overproduction/underexcretion

Stages of Gout

• Asymptomatic hyperuricemia: no need for treatment
• Acute gout
• Intercritical period: Asymptomatic periods between attacks
• Chronic tophaceous gout: Deformities and bone erosions
  • Punched-out appearance with overhanging edges
  • Acute gout presentation: Acute monoarthritis (commonly in the first metatarsophalangeal joint)
  • Differential diagnosis (DDX): Septic arthritis (differentiation through synovial fluid aspiration with polarized microscopy)
  • Findings on microscopy: Needle-shaped, negatively birefringent crystals
• Treatment of acute gout
  • NSAIDs (if no contraindications)
  • Colchicine (contraindicated in renal impairment and statin use)
  • Steroids (avoid in DM)
  • Local steroid injection
  • Anakinra (IL-1 agonist)

Treatment of Chronic Gout

• Lifestyle modification (diet)
• Urate-lowering drugs (5 indications)
• Education
• Correction of predisposing factors
• Avoiding hyperuricemic drugs
  • Thiazide diuretics
  • Loop diuretics (furosemide)
  • Niacin (B3)
  • Low doses of aspirin
• Foods to avoid
  • All meats
  • Seafood
  • Meat extracts
  • Yeast extracts
  • Beans
  • Lentils
  • Peas
  • Oats
  • Spinach
  • Asparagus
  • Cauliflower
  • Mushrooms

Indications for Urate-Lowering Treatment (ULT)

• Frequent flares (more than 2-3 flares per year)

• Renal stones

• Tophaceous gout (detected on radiographs)

• Moderate-to-severe CKD

• Evidence of bone or joint damage

• The risk of flares can be reduced by using prophylaxis like NSAIDs during the first few months following diagnosis

Urate-lowering drugs

• Allopurinol (available and cheap)
• Febuxostat (no need for dose reduction, Hypersensitivity reaction possible)
  • Side effects of Allopurinol (Xanthine oxidase inhibitors)
  • Dose Reduction due to renal function test (RFT)
• Uricosuric drugs
• Contraindicated in renal stones and overproducers/renal impairment.
• Uricase (IV)
• Pegloticase (expensive and used in refractory cases)

CPPD (Chondrocalcinosis)

• Causes
  • Idiopathic, closely related to osteoarthritis (OA)
  • Genetic mutation (early onset CPPD)
  • Secondary to other conditions
    • Hyperparathyroidism
    • Hypothyroidism
    • Lipomaquesemia
    • Hypophosphatemia
    • Hemochromatosis
    • Wilson's disease
• Presentation
  • Asymptomatic
  • Acute pseudogout (most common)
  • Chronic pseudo-RA (knee and wrist, monoarticular in 89%)
  • Chronic pseudo-OA
• Diagnosis
  • Synovial fluid aspiration under polarized microscopy (Rhomboid shape and positive birefringence)
  • X-ray shows chondrocalcinosis (calcium pyrophosphate deposition)
    • Knee meniscus
    • Wrist triangular

Treatment of Pseudogout

• Same as acute gout treatment, plus treatment of the underlying cause

• NSAIDs (if no contraindications)

• Colchicine (not given in renal impairment and statin use)

• Steroids (avoid in DM)

• Local steroid injection(s)

• Anakinra (IL-1 agonist)

• Problem in pseudogout: Calcium not uric acid