Target Serum Uric Acid Levels in Patients with Gout
For patients with a history of gout, serum uric acid should be maintained below 6 mg/dL (360 μmol/L), with a more aggressive target of less than 5 mg/dL (300 μmol/L) for those with severe disease manifestations until crystal dissolution is complete. 1, 2
Standard Target for All Gout Patients
Maintain serum uric acid below 6 mg/dL (360 μmol/L) lifelong in all patients receiving urate-lowering therapy, as this level is below the saturation point for monosodium urate crystals (6.8 mg/dL) and promotes crystal dissolution. 1, 2, 3
This target reduces the 1-year risk of acute gout attacks to approximately 5%, compared with 10-15% when levels remain at or above 6 mg/dL. 3, 4
The 6 mg/dL threshold must be maintained indefinitely, even after symptoms resolve, as approximately 40% of patients experience recurrence after stopping therapy. 2, 4
Aggressive Target for Severe Gout
For patients with tophi, chronic arthropathy, or frequent attacks (≥2 per year), target serum uric acid below 5 mg/dL (300 μmol/L) until complete crystal dissolution occurs. 1, 2, 3
Lower uric acid levels accelerate the velocity of tophus reduction and crystal dissolution, particularly important in patients with longer disease duration and greater crystal burden. 5, 6
Once tophi have resolved and crystals have dissolved completely, the target can be relaxed to the standard <6 mg/dL for maintenance. 1, 2
Important Caveats
Do not maintain serum uric acid below 3 mg/dL long-term, as uric acid may have protective effects against certain neurodegenerative diseases. 2, 3, 4
Serum uric acid should be measured regularly (typically every 2-4 weeks during dose titration, then periodically once at target) to ensure the therapeutic goal is maintained. 1
Common pitfall: Serum uric acid can be normal or even low during an acute gout attack due to its behavior as a negative acute-phase reactant, so do not use levels obtained during a flare to guide long-term management decisions. 4
Practical Implementation
Start allopurinol at 100 mg daily and increase by 100 mg every 2-4 weeks until the target uric acid level is achieved, with a maximum dose of 800 mg daily. 2, 3, 4
Mandatory flare prophylaxis: Provide colchicine 0.5-1 mg daily for at least 6 months when initiating urate-lowering therapy to prevent treatment-induced flares. 1, 2, 3, 4
If the target cannot be reached with appropriate allopurinol dosing, switch to febuxostat or add a uricosuric agent. 2