Serum Uric Acid Levels in Gout

Diagnostic Considerations

The European League Against Rheumatism (EULAR) guidelines state that serum uric acid levels do not confirm or exclude gout, as many people with hyperuricemia never develop gout, and patients with crystal-proven gout may have normal levels during acute attacks (strength of recommendation: 95, 95% CI 92-99) 1, 2, 3
Serum uric acid has limited diagnostic value during acute gout flares and should preferably be measured at distance from a flare 1, 4, 5
Approximately 10% of people with gout have serum uric acid levels below 6 mg/dL during flares 5

Serum uric acid behaves as a negative acute phase reactant during acute inflammation, temporarily decreasing when measured during gout attacks compared to intercritical periods 1, 4, 2, 3
Increased renal excretion of uric acid occurs during acute inflammatory episodes 1, 4
Acute inflammation and stress cause temporary lowering of serum uric acid levels 1, 2

For diagnostic purposes, serum uric acid should be measured during the intercritical period (between attacks) rather than during acute flares, as levels are typically higher when inflammation has resolved 1, 4, 5
For monitoring treatment efficacy, regular serum uric acid measurements are essential to ensure target levels below 6 mg/dL (360 μmol/L) are maintained, or below 5 mg/dL (300 μmol/L) in severe gout with tophi 6, 7

Hyperuricemia (male >7 mg/dL, female >6 mg/dL) has sensitivity of 57% and specificity of 92% for clinical gout, according to the European League Against Rheumatism guidelines 8
The European League Against Rheumatism recommends considering 24-hour urinary uric acid excretion in patients with family history of young-onset gout, gout onset before age 25, history of renal calculi, or consideration for uricosuric therapy 8

24-hour urinary uric acid excretion should be determined in selected patients, including those with family history of young-onset gout, gout onset before age 25, history of renal calculi, or consideration for uricosuric therapy, as recommended by the European League Against Rheumatism 8