A 42-year-old man with longstanding tophaceous gout has a serum urate of 9.8 mg/dL despite maximum-tolerated allopurinol. He has stage 3a CKD. The BEST addition to lower serum urate to target (<5 mg/dL for tophaceous gout) is:

• A Probenecid
• B Pegloticase (pegloticase infusion)
• C Febuxostat ✓
• D Colchicine long-term

Explanation

Febuxostat is a non-purine selective XO inhibitor that does not require dose adjustment until eGFR <30 mL/min, making it suitable in CKD stage 3a where probenecid (a uricosuric) is ineffective at eGFR <30 and best avoided in nephrolithiasis. Febuxostat can be added or substituted for allopurinol in patients not reaching urate targets. Pegloticase (recombinant uricase) is reserved for severe refractory tophaceous gout. Colchicine is for flare prophylaxis and has no urate-lowering effect. The CARES trial raised cardiovascular safety concerns with febuxostat vs allopurinol but subsequent analysis showed no excess risk without established CVD.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.