Creatinine Clearance Calculator (Cockcroft-Gault)
Calculate creatinine clearance using the Cockcroft-Gault equation. Primarily used for drug dosing adjustments.
Enter Patient Data
Patient age in years
Use actual body weight; for obesity, consider adjusted body weight
Used to calculate ideal body weight if needed
Standard serum creatinine measurement
Weight Adjustment
The calculator automatically uses:
- • Actual weight for normal patients
- • Adjusted body weight (ABW) if obese (>130% IBW)
- • ABW = IBW + 0.4 × (Actual - IBW)
Creatinine Clearance
Enter values to calculate
About This Calculator
The Cockcroft-Gault equation estimates creatinine clearance from serum creatinine. While eGFR (CKD-EPI) is preferred for CKD staging, Cockcroft-Gault CrCl remains the standard for drug dosing because most pharmacokinetic studies used this equation to establish dosing recommendations.
Formula
CrCl = [(140 - Age) × Weight × (0.85 if female)] / (72 × SCr)Where: • Age in years • Weight in kg (use actual body weight, or adjusted/ideal for obesity) • SCr = serum creatinine in mg/dL • Multiply by 0.85 for females Result is in mL/min (not adjusted for BSA).
Clinical Considerations
- •Use appropriate weight (actual vs. adjusted) based on patient body habitus
- •Results may be unreliable in acute kidney injury, rapidly changing creatinine
- •Original equation derived in 1976 with non-standardized creatinine assays
Limitations
- •May overestimate function in obese patients if actual weight used
- •May overestimate function in elderly or cachectic patients
- •Not validated in children
- •Assumes stable renal function (stable creatinine)
Interpretation Guide
| Range | Classification | Recommendation |
|---|---|---|
| 90-+ | Normal | Standard drug dosing typically appropriate |
| 60-89 | Mild Impairment | Check drug package inserts; some drugs may need adjustment |
| 30-59 | Moderate Impairment | Many drugs require dose reduction; check specific guidelines |
| 15-29 | Severe Impairment | Significant dose adjustments often needed; some drugs contraindicated |
| <-14 | End-Stage Renal Disease | Major adjustments required; consider dialyzability of medications |
Frequently Asked Questions
When should I use CrCl (Cockcroft-Gault) vs. eGFR (CKD-EPI)?
Use Cockcroft-Gault CrCl for drug dosing, as most pharmacokinetic studies used this equation. Use CKD-EPI eGFR for CKD staging and prognosis. The two values can differ significantly in certain patients.
Which weight should I use - actual, ideal, or adjusted?
For most patients, use actual body weight. For obese patients (>130% IBW), use adjusted body weight: IBW + 0.4 × (Actual - IBW). For severely underweight patients, use actual weight. Some drugs specify which weight to use.
Why is CrCl not adjusted for BSA?
Unlike eGFR (mL/min/1.73m²), Cockcroft-Gault CrCl is expressed in mL/min without BSA normalization. This is intentional for drug dosing, as drug clearance relates to absolute kidney function, not normalized values.
What are limitations of the Cockcroft-Gault equation?
Cockcroft-Gault may overestimate function in elderly or obese patients and underestimate in young muscular patients. It was derived in 1976 with non-standardized creatinine assays and a mostly male population.
Should I round up low creatinine values?
Some clinicians round SCr up to 1.0 mg/dL for elderly/cachectic patients to avoid overestimating function. However, this practice is controversial and not evidence-based. Use clinical judgment.
References
1. Cockcroft DW, Gault MH. Prediction of Creatinine Clearance from Serum Creatinine. Nephron. 1976. doi: 10.1159/000180580
View Source →2. U.S. Food and Drug Administration. FDA Guidance for Industry: Pharmacokinetics in Patients with Impaired Renal Function. 2020
View Source →Last updated: 2024-12-18
Auto-Calculate CrCl in Your Clinical Notes
PatientNotes AI automatically captures patient data during your visit and calculates relevant clinical values directly in your documentation. No manual entry needed—just review and approve.
7-day free trial • No credit card required • HIPAA compliant