Uric Acid

Reference Ranges

Reference ranges are typical adult values. Your laboratory may use slightly different intervals — always use your lab's reported reference.

What This Test Measures

Uric acid forms when purines (found in meat, seafood, beer, and produced endogenously from cell turnover) are broken down. Humans lack uricase — the enzyme that further metabolises urate — making us uniquely susceptible to hyperuricaemia. When urate concentrations exceed the solubility threshold (about 6.8 mg/dL), crystals form in joints and soft tissues, triggering gout.

When Is This Test Ordered?

• Diagnosing or monitoring gout
• Kidney stone evaluation (urate stones account for ~10% of urinary calculi)
• Monitoring urate-lowering therapy (allopurinol, febuxostat)
• Tumour lysis syndrome prevention in chemotherapy
• Metabolic syndrome risk assessment

Gout vs. serum urate: why the number can mislead

During an acute gout attack, serum urate often falls into the normal range because crystals are actively forming — urate is being pulled from the blood into joints. This is why a 'normal' uric acid during an attack does not rule out gout. Measure serum urate at least 4 weeks after an attack resolves for an accurate assessment.

Not everyone with high uric acid develops gout — only about 20% of people with hyperuricaemia develop clinical disease. The risk rises steeply above 9 mg/dL. Asymptomatic hyperuricaemia below 9 mg/dL does not require pharmacological treatment in most guidelines.

Factors That Can Affect Your Result

• High purine diet (red meat, organ meats, shellfish, beer) raises urate
• Alcohol raises urate by increasing purine synthesis and reducing renal excretion
• Fructose (sugar-sweetened beverages) raises urate by promoting purine breakdown
• Diuretics (thiazides, furosemide) raise urate by reducing renal excretion
• Aspirin has dual effects: low-dose raises urate; high-dose is uricosuric
• Serum urate falls during an acute gout flare — test between attacks for accurate baseline

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