Instructions
Enter the patient's age, weight, gender, and serum creatinine to calculate the creatinine clearance using the Cockcroft-Gault formula. This helps assess kidney function and guide medication dosing.
Age
Enter the patient's age in years
years
Weight
Enter the patient's weight
Gender
Select the patient's gender
Serum Creatinine
Enter the serum creatinine level from laboratory results
mg/dL
Creatinine Clearance Interpretation
≥ 90 mL/min: Normal kidney function (Stage 1 CKD)
60-89 mL/min: Mildly reduced kidney function (Stage 2 CKD)
30-59 mL/min: Moderately reduced kidney function (Stage 3 CKD)
15-29 mL/min: Severely reduced kidney function (Stage 4 CKD)
< 15 mL/min: Kidney failure (Stage 5 CKD)
Creatinine Clearance Calculator
The creatinine clearance calculator uses the Cockcroft-Gault formula to estimate glomerular filtration rate (GFR) based on serum creatinine, age, weight, and gender. This calculation is essential for medication dosing, particularly for drugs that are primarily excreted by the kidneys, and helps classify chronic kidney disease stages.
Cockcroft-Gault Formula
Where:
- Age: Patient age in years
- Weight: Patient weight in kilograms
- Serum Creatinine: Serum creatinine level in mg/dL
- 0.85: Correction factor for females (accounts for lower muscle mass)
Clinical Applications
Medication Dosing
- Antibiotics: Aminoglycosides, vancomycin, carbapenems
- Chemotherapy: Cisplatin, carboplatin, methotrexate
- Cardiovascular drugs: Digoxin, enalapril, metformin
- Analgesics: Morphine, codeine, tramadol
- Anticoagulants: Dabigatran, rivaroxaban (severe renal impairment)
Chronic Kidney Disease Staging
- Stage 1: ≥ 90 mL/min (Normal kidney function)
- Stage 2: 60-89 mL/min (Mildly reduced kidney function)
- Stage 3: 30-59 mL/min (Moderately reduced kidney function)
- Stage 4: 15-29 mL/min (Severely reduced kidney function)
- Stage 5: < 15 mL/min (Kidney failure)
Interpretation of Results
Normal Kidney Function (≥ 90 mL/min)
- Clinical significance: Normal kidney function
- Medication dosing: Standard dosing usually appropriate
- Monitoring: Routine monitoring sufficient
- Clinical implications: No dose adjustments typically needed
Mildly Reduced Function (60-89 mL/min)
- Clinical significance: Early kidney disease
- Medication dosing: Monitor for nephrotoxic drugs
- Monitoring: Regular kidney function monitoring
- Clinical implications: Consider dose adjustments for some medications
Moderately Reduced Function (30-59 mL/min)
- Clinical significance: Moderate kidney disease
- Medication dosing: Dose adjustments often required
- Monitoring: Frequent monitoring needed
- Clinical implications: Avoid nephrotoxic agents when possible
Severely Reduced Function (15-29 mL/min)
- Clinical significance: Severe kidney disease
- Medication dosing: Significant dose reductions required
- Monitoring: Close monitoring essential
- Clinical implications: Consider nephrology consultation
Kidney Failure (< 15 mL/min)
- Clinical significance: End-stage kidney disease
- Medication dosing: Major dose adjustments or alternative agents
- Monitoring: Very close monitoring required
- Clinical implications: Nephrology consultation recommended
Important Considerations
Limitations of Cockcroft-Gault Formula
- Elderly patients: May overestimate GFR due to reduced muscle mass
- Muscle wasting: May overestimate GFR in cachectic patients
- Obesity: May overestimate GFR in obese patients
- Amputation: May overestimate GFR in amputees
- Pregnancy: Not validated in pregnancy
- Children: Not validated in pediatric populations
When to Use Alternative Methods
- MDRD equation: More accurate for GFR < 60 mL/min
- CKD-EPI equation: More accurate across all GFR ranges
- Measured GFR: Gold standard using inulin or radioisotopes
- Cystatin C: Alternative marker less affected by muscle mass
Special Populations
- Elderly patients: Consider using CKD-EPI equation
- African Americans: May need race adjustment in some equations
- Liver disease: Creatinine production may be reduced
- Critical illness: Dynamic changes in kidney function
Clinical Pearls
- Always consider the clinical context when interpreting results
- Use the most appropriate equation for the patient population
- Monitor trends over time rather than single values
- Consider other factors affecting creatinine (muscle mass, diet, medications)
- Document which equation was used in medical records
- Reassess if clinical picture doesn't match calculated clearance
- Consider nephrology consultation for severe kidney disease
Medication Dosing Guidelines
Dose Adjustment Categories
- No adjustment needed: CrCl ≥ 50 mL/min
- Mild adjustment: CrCl 30-49 mL/min
- Moderate adjustment: CrCl 10-29 mL/min
- Major adjustment: CrCl < 10 mL/min
Common Medications Requiring Adjustment
- Antibiotics: Gentamicin, vancomycin, ciprofloxacin
- Analgesics: Morphine, codeine, tramadol
- Cardiovascular: Digoxin, enalapril, metformin
- Chemotherapy: Cisplatin, carboplatin, methotrexate
- Anticoagulants: Dabigatran, rivaroxaban
Monitoring Recommendations
Frequency of Monitoring
- Normal function: Annual monitoring
- Mild reduction: Every 6 months
- Moderate reduction: Every 3 months
- Severe reduction: Monthly or more frequently
- Kidney failure: Weekly or as clinically indicated
Additional Monitoring
- Electrolytes (sodium, potassium, bicarbonate)
- Calcium and phosphorus
- Hemoglobin and iron studies
- Parathyroid hormone
- Vitamin D levels
- Urine protein excretion
This calculator provides a standardized method for estimating kidney function, which is crucial for medication dosing, prognostic assessment, and clinical decision-making. The Cockcroft-Gault formula remains widely used in clinical practice, particularly for medication dosing decisions.
References
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41.
- Levey AS, et al. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Ann Intern Med. 1999;130(6):461-470.
- Stevens LA, et al. Estimating GFR using serum cystatin C alone and in combination with serum creatinine: a pooled analysis of 3,418 individuals with CKD. Am J Kidney Dis. 2008;51(3):395-406.
- National Kidney Foundation. K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Am J Kidney Dis. 2002;39(2 Suppl 1):S1-266.
- Levey AS, et al. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med. 2006;145(4):247-254.
Loading PDF...