Gout

Definition

  • Inflammatory arthritis caused by the accumulation of urate crystals (monosodium urate), can lead to depositions of uric acid crystals (tophi)

Risk

  • Alcohol intake
  • Hypertension
  • Obesity
  • Renal failure
  • Diuretic use
  • Diet rich in meat, seafood, and high-fructose

Diagnosis

  • Urate crystals on joint aspirate (negatively birefringent needle-shaped crystals on polarization)
  • Consider diagnostic rule when aspirate not available (male, reported attack, onset within 1d, joint redness, 1st MTP involvement, HTN, elevated uric acid)

Treatment (patient should self-medicate early if possible)

  • NSAIDs* (most effective within 48h of flare onset), eg. Naproxen 500mg BID until 1-2d after flare resolution (usually 5-7d) +/- PPI
  • Colchicine* (within 12h of flare onset) 1.2 mg, followed one hour later by another 0.6 mg (total 1.8 mg Day 1), then 0.6mg PO daily-BID until 2-3d after flare resolution
    • *Avoid NSAIDs/Colchicine in severe renal impairment
    • Avoid Colchicine P-glycoprotein/CYP3A4 inhibitors (eg. antiretroviral, antifungals, clarithromycin, amiodarone, diltiazem, verapamil)
  • Oral corticosteroid, eg. Prednisone 30–40 mg/day (can divide BID) until flare resolution then tapered over 7 days (consider longer 14-21d course in recurrent gout)
    • If only acute monoarticular gout (septic joint ruled out), consider articular aspiration and injection of corticosteroids
  • Consider referral to Rheumatology (or Surgery for tophi)
    • Consider combination or IL-1 inhibitors if not responding to above
  • Do not interrupt ongoing urate-lowering therapy
  • If gout flare on loop or thiazide diuretics, substitute for losartan or calcium channel blockers
    • Screen/treat underlying cardiovascular risk factors (eg. statin for hyperlipidemia can reduce uric acid)

Patient education

  • Causes/consequences of gout
  • Teaching on management and self-medication for future gout flares
  • Lifestyle modification
    • Weight loss if appropriate (regular exercise/diet)
    • Avoidance of alcohol, sugar-sweetened (high-fructose corn syrup) drinks/food, meat and seafood (purine)
    • Dairy products, vitamin C and coffee might protect

Urate Lowering Therapy (ULT)

  • Indicated in patients with any of: recurrent flares (≥2 attacks in 12 months), tophi, urate arthropathy, evidence of radiographic damage, or urolithiasis
  • May consider initiating ULT in first gout flare if comorbid CKD stage ≥3, Serum Uric Acid concentration >9 mg/ dl
  • Xanthine oxidase inhibitor
    • Allopurinol initial 100mg PO daily, most increase by 100mg q2–4 weeks to a maintenance of 300mg PO daily
      • No clear evidence of benefit of target dose vs. target Serum Uric Acid Level (a systematic review of 10 RCTS found no relationship between serum urate level and gout flare, but retrospective cohort studies show an association did find an association)
        • Despite this, some guidelines still recommend a target Serum Uric Acid level <6 mg/dl (360 µmol/L), and <5 mg/dl (300 µmol/L) for severe gout
          • If target not reached (or not tolerated) may consider switch to Febuxostat (although increases mortality) or a uricosuric (Probenecid)
      • Assess risk for severe allopurinol hypersensitivity reaction
        • Consider screening Han Chinese, Thai, and Koreans (some specify Korean only with CKD) for HLA–B*5801 by PCR
    • Prophylaxis is recommended during the first 6 months of ULT
      • Colchicine 0.6 mg daily-BID, or NSAIDs, or steroids

Gout Treatment