Uric Acid
Uric Acid· also: Uric Acid, Serum Urate
Clinical Overview
Uric acid is the final breakdown product of purine metabolism. Purines are found in nucleic acids (DNA, RNA) and are abundant in red meat, organ meats, shellfish, and beer. Elevated uric acid (hyperuricemia) can crystallize in joints causing gout and in the kidneys causing uric acid stones.
Why This Test Matters
Hyperuricemia is the metabolic basis of gout — the most common inflammatory arthritis in adults. Uric acid crystals deposit in joints (especially the big toe, ankles, and knees), causing exquisitely painful attacks. Chronic hyperuricemia is also associated with kidney stones, hypertension, metabolic syndrome, and cardiovascular disease. Treatment with allopurinol or febuxostat targets a uric acid level below 6 mg/dL.
Reference RangesWHO/IFCC standards
| Age Group | Sex | Reference Range | Unit | Notes |
|---|---|---|---|---|
| Adults (18–64) | Male | 3.4 – 7 | mg/dL | — |
| Adults (18–64) | Female | 2.4 – 6 | mg/dL | — |
Also reported in: µmol/L.
Critical (Panic) Values
Critical High: > 13 mg/dL. Values outside these limits require immediate clinical attention.
What Causes Abnormal Results?
High Uric Acid Causes
- Gout (most clinically relevant cause)
- High purine diet: red meat, organ meats, shellfish, beer
- Kidney disease (reduced uric acid excretion)
- Diuretics (thiazides, loop diuretics) — reduce uric acid excretion
- Tumor lysis syndrome (massive cell death releases purines)
- Psoriasis (increased cell turnover)
- Myeloproliferative disorders (increased cell turnover)
- Hypothyroidism
Low Uric Acid Causes
- Xanthine oxidase inhibitor therapy (allopurinol, febuxostat)
- Low purine diet
- Liver disease (reduced purine synthesis)
- Medications: high-dose salicylates (aspirin), losartan, fenofibrate (uricosuric effect)
Signs & Symptoms to Watch For
How to Prepare for This Test
No fasting strictly required but preferred. Avoid purine-rich foods and alcohol for 24 hours before testing for the most accurate baseline. Inform your doctor if you are on allopurinol or diuretics.
Factors That Can Affect Results
- Diet (high purine foods raise uric acid)
- Alcohol (especially beer — raises uric acid and triggers gout attacks)
- Dehydration (concentrates uric acid)
- Thiazide and loop diuretics (raise uric acid)
- Low-dose aspirin (reduces uric acid excretion)
- Fructose-containing beverages (raise uric acid)
Related Topics
Frequently Asked Questions
Does everyone with a high uric acid level get gout?
No. Most people with hyperuricemia never develop gout. The risk increases with higher uric acid levels and longer duration of hyperuricemia, but gout only develops when urate crystals actually form and trigger an immune response. Factors like dehydration, alcohol, a purine-rich meal, or joint trauma can precipitate a gout attack in susceptible individuals.
Can I have gout with a normal uric acid level?
Yes. Uric acid levels can be normal or even low during an acute gout attack because urate crystals deposit in joints, temporarily reducing serum uric acid. For diagnosis during an attack, joint fluid analysis (finding needle-shaped negatively birefringent urate crystals under polarized light microscopy) is the gold standard. Uric acid should be measured 4–6 weeks after the attack resolves for accurate assessment.