Uric Acid Biomarker | Walk-In Lab

Overview

Uric acid is a waste product of purine metabolism that is measured in blood or urine to assess how the body produces and eliminates purines. MedlinePlus notes that the uric acid test measures the amount of uric acid in a sample of blood or urine and is used because abnormal levels can lead to health problems such as gout and kidney disease. High uric acid levels (hyperuricemia) are associated with gout, kidney stones, and can occur with kidney dysfunction or rapid cell turnover (for example during cancer chemotherapy). Low uric acid levels (hypouricemia) are less common but may be seen with certain medications, inherited disorders of purine metabolism, or some systemic diseases. Clinically, uric acid is useful to help diagnose and monitor gout, evaluate kidney function, investigate kidney stones, and monitor patients receiving cytotoxic or cancer therapies.

Clinical Use Cases

Diagnose and help manage gout when combined with clinical assessment and, often, synovial fluid analysis.
Diagnose and monitor hyperuricemia in patients with or at risk for high uric acid levels.
Evaluate and monitor kidney function and renal failure, including investigation of kidney stones and other kidney disorders.
Monitor uric acid in patients receiving chemotherapy, radiation, or other cytotoxic drugs, to detect treatment‑related increases in uric acid (tumor lysis) and prevent complications.
Assist in management of conditions with high cell turnover or catabolic states, such as leukemia, psoriasis, starvation and other wasting conditions.
Assess potential causes of recurrent kidney stones and guide therapy to reduce stone formation.
Monitor patients on urate‑lowering therapy to maintain target uric acid levels (often below 6 mg/dL) in gout management.

Specimen Types

Serum.
Plasma (lithium heparin plasma and K2‑EDTA plasma; EDTA plasma values are typically slightly lower than serum).
Urine (24‑hour or timed collections for urinary uric acid excretion).

Measurement Methods

Automated enzymatic uricase methods performed on clinical chemistry analyzers (for example, DXC 800/660i and similar systems used in NHANES and hospital laboratories).
General colorimetric/photometric assays based on uricase conversion of uric acid, measured by absorbance on routine chemistry platforms.

Test Preparation and Influencing Factors

Fasting requirements
- Large public health protocols (for example CDC NHANES) state that fasting is not required for serum uric acid measurement.
- Some laboratories and clinics may recommend several hours of fasting (for example 4–8 hours) before the test; patients should follow the specific instructions given by their provider.
Medications
- Many medicines can affect uric acid levels, including aspirin, diuretics, niacin (vitamin B3), and other drugs.
- Diuretics (such as thiazide and loop diuretics) commonly increase serum uric acid via changes in renal handling and fluid loss.
- Other drugs used to treat gout or hyperuricemia (for example, urate‑lowering therapy) intentionally lower uric acid and will influence results; medication changes should only be made in consultation with a clinician.
Diet and alcohol
- Purine‑rich foods (red meat, some seafood), sugar‑sweetened beverages (soft drinks), and alcohol (especially beer and liquor) are associated with higher serum uric acid levels.
- Dairy products such as skim milk and some plant foods are associated with lower uric acid levels.
- Alcohol intake before testing may interfere with results and is often discouraged.
Vitamins and other substances
- High doses of vitamin C and contrast dyes used for X‑ray studies can affect test results.
Physiological variables
- Uric acid levels vary with age and sex, and can be influenced by exercise, hydration status, and short‑term dietary changes.
- Chronic conditions such as obesity, insulin resistance, hypertension, hypothyroidism, chronic kidney disease, and iron overload are associated with higher uric acid levels.
Timing and specimen handling
- For blood tests, serum or plasma should be separated from cells promptly (within about an hour) and stored under appropriate conditions to prevent analytic errors.
- Urine collections require careful adherence to timing and collection instructions to accurately assess excretion.