Serum Uric Acid Reference Ranges
Standard Laboratory Reference Ranges
The traditional reference ranges for serum uric acid are 3.5–7.2 mg/dL (208–428 μmol/L) in adult men and postmenopausal women, and 2.6–6.0 mg/dL (155–357 μmol/L) in premenopausal women. 1
Adult Men
- Reference range: 4.0–9.2 mg/dL based on the 2.5th to 97.5th percentile from a large Brazilian cohort study (ELSA-Brasil) that excluded individuals with factors directly influencing uric acid levels 2
- Traditional range: 3.5–7.2 mg/dL 1
- Median values: approximately 6.1 mg/dL (IQR 5.3–7.0) 2
Adult Women (Premenopausal)
- Reference range: 2.8–6.9 mg/dL based on rigorous exclusion criteria 2
- Traditional range: 2.6–6.0 mg/dL 1
- Median values: approximately 4.5 mg/dL (IQR 3.9–5.3) 2
- Optimal range for lowest cardiometabolic risk: 2–4 mg/dL 3
Adult Women (Postmenopausal)
- Reference range: 3.5–7.2 mg/dL (similar to men) 1
Children
While specific pediatric reference ranges are not extensively detailed in the provided guidelines, uric acid levels in children are generally lower than adults and increase with age, particularly during puberty. 4
Pregnancy
Serum uric acid levels during pregnancy are not specifically addressed in the provided evidence, though normal pregnancy typically involves lower uric acid levels in early pregnancy with gradual increases in the third trimester.
Important Clinical Context
Laboratory Variability
- Most laboratories calculate their own reference ranges as mean ± 2 standard deviations from their local healthy population, stratified by sex 5
- Laboratory-specific approaches may increase diagnostic accuracy (likelihood ratio up to 9.74) 5
- Always check the specific reference range provided by the testing laboratory 5
Sex Differences
- Men have consistently higher serum uric acid levels than women due to hormonal differences 5, 2
- This sex difference is the primary reason for separate reference ranges 5
- The difference is statistically significant across all age groups until menopause 2
Racial and Ethnic Variations
- Among 38 standard laboratory tests analyzed in NHANES, uric acid was one of only five that did not show significant racial/ethnic differences in distribution 4
- This makes uric acid reference ranges more universally applicable across populations than many other laboratory values 4
Clinical Pitfalls and Caveats
The "Normal Range" Controversy
- Traditional reference ranges may be too high and should be reconsidered 1
- A threshold value <6.0 mg/dL (<360 μmol/L) may better identify truly healthy subjects, as higher values are associated with silent monosodium urate crystal deposition and cardiometabolic disease risk 1
- The worldwide increase in circulating uric acid levels has led to a "shift to right" in population distributions, potentially inflating what we consider "normal" 1
Gout-Specific Considerations
- Hyperuricemia is traditionally defined as >7 mg/dL in men and >6 mg/dL in women for gout risk assessment 5
- However, serum uric acid levels have limited diagnostic value for gout, with sensitivity of only 57% and specificity of 92% 4, 6
- Approximately 10% of patients with crystal-proven gout have serum uric acid <6 mg/dL during acute flares 6
- Uric acid acts as a negative acute-phase reactant, temporarily decreasing during acute inflammation 6, 7
Treatment Targets (Not Reference Ranges)
- For gout management, target serum uric acid <6 mg/dL (<360 μmol/L) in all patients 4
- In severe gout with tophi, target <5 mg/dL (<300 μmol/L) until clinical remission 4
- These treatment targets are distinct from reference ranges and represent therapeutic goals 4