Creatinine Clearance Calculator
Calculate creatinine clearance (CrCl) using the Cockcroft-Gault formula for medication dosing in renal impairment.
How Creatinine Clearance Works
Creatinine clearance (CrCl) estimates kidney function by calculating how efficiently the kidneys filter creatinine from the blood. The Cockcroft-Gault formula uses age, weight, sex, and serum creatinine to estimate CrCl in mL/min.
Lower CrCl values indicate worse kidney function and guide medication dose adjustments. The formula accounts for physiological decline in kidney function with age and differences between males and females.
Formula
Worked Examples
Example 1: 70-year-old male, 80 kg, serum creatinine 1.5 mg/dL. Calculate CrCl.
Age = 70 years, Weight = 80 kg, Cr = 1.5 mg/dL, Sex = male (factor 1.0)
Numerator = (140 - 70) × 80 × 1.0 = 5600
Denominator = 72 × 1.5 = 108
CrCl = 5600 / 108 = 51.9 mL/min
Example 2: 65-year-old female, 70 kg, serum creatinine 1.2 mg/dL. Calculate CrCl.
Age = 65 years, Weight = 70 kg, Cr = 1.2 mg/dL, Sex = female (factor 0.85)
Numerator = (140 - 65) × 70 × 0.85 = 4462.5
Denominator = 72 × 1.2 = 86.4
CrCl = 4462.5 / 86.4 = 51.6 mL/min
Example 3: 85-year-old male, 65 kg, serum creatinine 1.0 mg/dL. Calculate CrCl.
Age = 85 years, Weight = 65 kg, Cr = 1.0 mg/dL, Sex = male (factor 1.0)
Numerator = (140 - 85) × 65 × 1.0 = 3575
Denominator = 72 × 1.0 = 72
CrCl = 3575 / 72 = 49.7 mL/min
When This Calculator Is Used
- •Medication dose adjustments for renally-cleared drugs
- •Chronic kidney disease (CKD) staging and monitoring
- •Pre-operative risk assessment for kidney function
- •Contrast media dosing for imaging studies
- •Chemotherapy dosing (e.g., carboplatin AUC calculations)
Clinical safety note: Always confirm current serum creatinine and clinical status. CrCl is an estimate and may not reflect actual kidney function in all patients (e.g., extremes of body weight, muscle mass, or acute kidney injury). Verify medication dosing with current clinical guidelines and drug monographs.
Related Calculators
Frequently Asked Questions
Clinical reminder: Always follow local protocols and consult medication information sheets. These examples are for calculation practice only.
References & Sources
This calculator is based on the original Cockcroft-Gault formula and international clinical practice guidelines for medication dosing in renal impairment.