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:
Uric Acid Clearance (mL/min) =
Urine Uric Acid × Urine Volume
Serum Uric Acid × Time (min)
*Units: Urine/Serum Uric Acid (mg/dL), Urine Volume (mL)
*Normal range: 6-12 mL/min (varies by lab)
*Low in renal dysfunction; High in overproduction
*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:
Uric Acid Clearance (mL/min) =
Urine Uric Acid (mg/dL) × Urine Volume (mL)
Serum Uric Acid (mg/dL) × Time (min)
Normal: 6-12 mL/min
High: >12 mL/min (overproduction)
Low: <6 mL/min (renal impairment)
*Standard 24-hour urine collection recommended
*Corrected for body surface area in pediatric cases
*Corrected for body surface area in pediatric cases
- Adjusting for Liters and Hours:
Uric Acid Clearance (mL/min) =
Urine Uric Acid (mg/dL) × (Urine Volume (L) × 1000)
Serum Uric Acid (mg/dL) × (Time (hr) × 60)
Unit Conversions:
1 L = 1000 mL
1 hr = 60 min
1 hr = 60 min
Clinical Range:
6-12 mL/min (normal)
>12 mL/min (overproduction)
>12 mL/min (overproduction)
*Blue: Volume conversion | Red: Time conversion
*For 24hr collection: Time = 24hr, Volume = total mL/1000
*For 24hr collection: Time = 24hr, Volume = total mL/1000
- For mmol/L Units:
Uric Acid Clearance (mL/min) =
Urine Uric Acid (mmol/L) × Urine Volume (mL)
Serum Uric Acid (mmol/L) × Time (min)
SI Units:
1 mmol/L = 16.81 mg/dL
No conversion factors needed
No conversion factors needed
Clinical Interpretation:
Normal: 6-12 mL/min
Fractional excretion: 7-20%
Fractional excretion: 7-20%
*Preferred units for international journals
*Multiply urine volume (L) × 1000 if needed
*Multiply urine volume (L) × 1000 if needed
- Conversion to Daily Rate (L/day):
Clearance (L/day) =
Clearance (mL/min)
×
1440 min/day
1000 mL/L
Conversion Factors:
1440 = minutes per day
1000 = mL per liter
1000 = mL per liter
Simplified Form:
L/day = mL/min × 1.44
(1440/1000 = 1.44)
(1440/1000 = 1.44)
*Multiply mL/min result by 1.44 for daily clearance
*Useful for comparing with GFR (typically reported in L/day)
*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
Clearance =
50 mg/dL × 1200 mL
6 mg/dL × 1440 min
=
60,000
8,640
≈ 6.94 mL/min
Input Values:
• Urine Uric Acid: 50 mg/dL
• Urine Volume: 1200 mL/24hr
• Serum Uric Acid: 6 mg/dL
• Urine Volume: 1200 mL/24hr
• Serum Uric Acid: 6 mg/dL
Interpretation:
• Normal range (6-12 mL/min)
• Suggests normal renal excretion
• Suggests normal renal excretion
*Example calculation for 24-hour urine collection
*1440 minutes = 24 hours
*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
Clearance =
0.3 mmol/L × 2000 mL
0.36 mmol/L × 720 min
=
600
259.2
≈ 2.31 mL/min
Input Values (SI Units):
• Urine Uric Acid: 0.3 mmol/L
• Urine Volume: 2000 mL/12hr
• Serum Uric Acid: 0.36 mmol/L
• Urine Volume: 2000 mL/12hr
• Serum Uric Acid: 0.36 mmol/L
Clinical Interpretation:
• Below normal (6-12 mL/min)
• Suggests renal impairment or under-excretion
• Suggests renal impairment or under-excretion
*720 minutes = 12-hour urine collection
*Conversion: 1 mmol/L = 16.81 mg/dL
*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.
