The Uric Acid Clearance Calculator evaluates the kidneys’ efficiency in removing uric acid from the bloodstream. This metric aids in diagnosing disorders like gout, chronic kidney disease, or metabolic syndromes. By comparing urinary excretion to serum levels, clinicians assess renal handling of uric acid.
Definition
Uric Acid Clearance measures the volume of blood cleared of uric acid per minute (mL/min) or per day (L/day). It reflects glomerular filtration, tubular reabsorption, and secretion. Abnormal clearance rates indicate altered uric acid metabolism or kidney dysfunction.
Core Formula
The standard formula for uric acid clearance is:
*Normal range: 6-12 mL/min (varies by lab)
*Low in renal dysfunction; High in overproduction
Formula Variations by Units
- Using mg/dL and mL/min:
*Corrected for body surface area in pediatric cases
- Adjusting for Liters and Hours:
1 hr = 60 min
>12 mL/min (overproduction)
*For 24hr collection: Time = 24hr, Volume = total mL/1000
- For mmol/L Units:
No conversion factors needed
Fractional excretion: 7-20%
*Multiply urine volume (L) × 1000 if needed
- Conversion to Daily Rate (L/day):
1000 = mL per liter
(1440/1000 = 1.44)
*Useful for comparing with GFR (typically reported in L/day)
🧮 Uric Acid Clearance Calculator
📐 Formula:
Clearance (mL/min) = (Urine Uric Acid × Urine Volume) / (Serum Uric Acid × Time in minutes)
Usually, time is 1440 minutes (24 hours).
🖊️ Enter the Values:
Unit Conversions
| Conversion | Factor |
|---|---|
| g/dL → mmol/L | × 0.0595 |
| mmol/L → mg/dL | × 16.81 |
| dL → mL | × 100 |
| L → mL | × 1000 |
| hr → min | × 60 |
Step-by-Step Calculation Examples
Example 1: Basic Calculation (mg/dL and mL)
- Urine Uric Acid: 50 mg/dL
- Urine Volume: 1200 mL (1.2 L)
- Serum Uric Acid: 6 mg/dL
- Time: 24 hours = 1440 min
• Urine Volume: 1200 mL/24hr
• Serum Uric Acid: 6 mg/dL
• Suggests normal renal excretion
*1440 minutes = 24 hours
Example 2: Using mmol/L and Adjusted Units
- Urine Uric Acid: 0.3 mmol/L
- Urine Volume: 2 L = 2000 mL
- Serum Uric Acid: 0.36 mmol/L
- Time: 12 hours = 720 min
• Urine Volume: 2000 mL/12hr
• Serum Uric Acid: 0.36 mmol/L
• Suggests renal impairment or under-excretion
*Conversion: 1 mmol/L = 16.81 mg/dL
Normal Values
- Uric Acid Clearance: 6–10 mL/min (varies by lab and method).
- Serum Uric Acid:
- Men: 3.4–7.0 mg/dL (202–416 µmol/L)
- Women: 2.4–6.0 mg/dL (143–357 µmol/L)
Interpretation
- Elevated Clearance (>10 mL/min): May indicate increased excretion (e.g., untreated gout, tumor lysis syndrome).
- Reduced Clearance (<6 mL/min): Suggests impaired excretion (chronic kidney disease, lead poisoning).
Clinical Relevance
- Gout Management: Assess overproduction vs. underexcretion of uric acid.
- Kidney Disease: Monitor progression of renal dysfunction.
- Drug Monitoring: Evaluate efficacy of uricosuric agents (e.g., probenecid).
Limitations
- Requires accurate 24-hour urine collection.
- Serum levels fluctuate with diet, hydration, and circadian rhythm.
- Does not distinguish between glomerular/tubular dysfunction.
Key Takeaways
- Uric acid clearance reflects renal excretion efficiency.
- Formula adjusts for urine volume, serum levels, and time.
- Normal range: 6–10 mL/min.
- Use unit conversions to ensure consistency.
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