Normal Serum Uric Acid Values
Normal serum uric acid levels are 2.6-6.0 mg/dL in premenopausal women and 3.5-7.2 mg/dL in adult males and postmenopausal women, though emerging evidence suggests values below 6.0 mg/dL may be optimal for all adults. 1
Gender-Specific Reference Ranges
- Men and postmenopausal women: 3.5-7.2 mg/dL 1
- Premenopausal women: 2.6-6.0 mg/dL 1
- Men typically have higher serum uric acid levels than women, which is why different reference ranges are used for each gender 2
Laboratory-Specific Considerations
- Most laboratories calculate their own cut-off level for hyperuricemia as the mean plus two standard deviations from their local healthy population, calculated separately for men and women 2
- This laboratory-specific approach may increase the likelihood ratio for detecting true hyperuricemia up to 9.74 (95% CI, 7.45 to 12.72) 2
- Always check the specific reference range provided by the laboratory performing the test, as values may vary between institutions 2
Clinical Thresholds for Disease Risk
Hyperuricemia Definition
- Hyperuricemia is defined as >7 mg/dL in males and >6 mg/dL in females according to European League Against Rheumatism guidelines 3
- This threshold has sensitivity of 57% and specificity of 92% for clinical gout 3
Gout Risk Stratification
- A serum uric acid level above 6 mg/dL is associated with increased risk of gout, with risk increasing proportionally with higher levels 2
- The risk of developing gout is over four times higher in men and 17 times higher in women who have serum uric acid levels >6 mg/dL compared to those with levels below this threshold 2
Emerging Optimal Target Range
- A threshold value <6.0 mg/dL (<360 µmol/L) may better identify truly healthy subjects and should be considered for all individuals, regardless of gender 1
- Available information suggests a treatment target with serum UA levels between 5.0 and 6.0 mg/dL as reasonable 4
- This lower threshold accounts for the pathophysiological role of uric acid in cardio-nephro-metabolic disorders, which occurs even below the saturation point for monosodium urate crystals 1
Important Clinical Caveats
Fluctuations During Acute Illness
- Serum uric acid levels can fluctuate during acute gout attacks, sometimes falling to normal or near-normal levels during an attack 2
- Uric acid behaves as a negative acute phase reactant, being temporarily lowered during episodes of acute inflammation and stress 2, 3
- Approximately 10% of people with gout have serum uric acid levels below 6 mg/dL during flares 3
Factors Affecting Levels
- Uric acid levels may be affected by diet, medications (especially diuretics), and renal function 2
- Cystatin C, creatinine, albumin, triglycerides, body mass index (BMI), and diuretic therapy are the major determinants of heterogeneity of UA levels 5
Interpretation Pitfalls
- Normal uric acid levels do not exclude gout, particularly during acute attacks when levels may temporarily decrease 2
- Conversely, elevated uric acid levels do not necessarily indicate gout, as many people with hyperuricemia never develop gout 2, 3
- For diagnostic purposes, serum uric acid should be measured during the intercritical period (between attacks) rather than during acute flares 3