A 65-year-old man with tophaceous gout has serum urate of 9.8 mg/dL despite allopurinol 300 mg/day. His eGFR is 52 mL/min. He reports multiple gout flares per year. Which management step is most appropriate?
- A Add probenecid to enhance urate excretion
- B Add pegloticase infusions as first-line escalation
- C Switch to febuxostat 80 mg/day ✓
- D Increase allopurinol to 600 mg/day regardless of renal function
Explanation
When allopurinol fails to achieve target urate <6 mg/dL, febuxostat is the preferred second-line xanthine oxidase inhibitor, effective in moderate CKD (eGFR >30) and not requiring dose adjustment based on renal function to the same degree as allopurinol. Target serum urate is <5–6 mg/dL for tophaceous gout. Probenecid (uricosuric) is contraindicated in CKD (eGFR <50) and urolithiasis. Pegloticase (pegylated uricase) is reserved for refractory tophaceous gout failing oral urate-lowering therapy. Allopurinol dose >300 mg/day in CKD stage 3 risks severe cutaneous reactions (SJS/TEN).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.