Creatinine Clearance Calculator

This calculator estimates kidney function by calculating creatinine clearance (CrCl) using the Cockcroft-Gault equation, which helps healthcare professionals assess renal function and adjust medication dosages accordingly.

How to Use This Calculator

Enter the patient's serum creatinine value in mg/dL
Enter the patient's age in years
Enter the patient's weight in kilograms
Select the patient's gender
Click Calculate to see the creatinine clearance result

Formula Used

CrCl (mL/min) = [(140 - Age) × Weight (kg)] / [72 × Serum Creatinine (mg/dL)] × 0.85 (for females)

Where:

CrCl = Creatinine clearance in mL/min
Age = Patient's age in years
Weight = Patient's weight in kilograms
Serum Creatinine = Blood creatinine level in mg/dL
0.85 = Adjustment factor for females

Example Calculation

Real-World Scenario:

A 65-year-old male patient weighing 80 kg with a serum creatinine level of 1.5 mg/dL needs his kidney function assessed before starting a new medication.

Given:

Serum Creatinine = 1.5 mg/dL
Age = 65 years
Weight = 80 kg
Gender = Male

Calculation:

CrCl = [(140 - 65) × 80] / [72 × 1.5]

CrCl = [75 × 80] / [108]

CrCl = 6000 / 108

Result: 55.6 mL/min (mildly decreased kidney function)

Why This Calculation Matters

Clinical Applications

Medication dosing adjustments for patients with impaired kidney function
Monitoring progression of chronic kidney disease
Evaluating eligibility for certain diagnostic procedures with contrast agents

Interpretation Guidelines

>90 mL/min: Normal kidney function
60-90 mL/min: Mildly decreased kidney function
30-60 mL/min: Moderately decreased kidney function
<30 mL/min: Severely decreased kidney function

Common Mistakes & Tips

The Cockcroft-Gault equation requires specific units: serum creatinine in mg/dL (not μmol/L), weight in kilograms (not pounds), and age in years. Using incorrect units will lead to significantly incorrect results.

The standard Cockcroft-Gault equation calculates creatinine clearance without adjusting for body surface area. For certain clinical decisions, you may need to adjust the result to 1.73 m² body surface area, especially when comparing results to standard reference ranges.

Frequently Asked Questions

The Cockcroft-Gault equation is reasonably accurate for most adult patients but has limitations. It may overestimate kidney function in elderly patients and those with low muscle mass. For more precise measurements, consider using newer equations like MDRD or CKD-EPI, or direct measurement methods like inulin clearance.

For patients who are significantly overweight or obese (BMI >30), many clinicians recommend using adjusted body weight rather than actual body weight. Adjusted body weight = Ideal body weight + 0.4 × (Actual body weight - Ideal body weight). This helps prevent overestimation of kidney function in obese patients.

For patients with stable kidney function, monitoring every 6-12 months is typically sufficient. Patients with chronic kidney disease, those on nephrotoxic medications, or those with fluctuating medical conditions may require more frequent monitoring, sometimes as often as monthly.

References & Disclaimer

Medical Disclaimer

This calculator is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

References

Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. - Nephron. 1976;16(1):31-41.
National Kidney Foundation. GFR Calculator. - Clinical practice guidelines for estimating GFR.
Levey AS, Stevens LA. Assessment of kidney function. - UpToDate. 2023.

Accuracy Notice

The Cockcroft-Gault equation has limitations and may not be accurate in certain populations, including the elderly, children, pregnant women, patients with unusual body composition, or those with unstable kidney function. For critical clinical decisions, consider using more accurate methods of kidney function assessment.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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