How Creatinine Clearance (Cockcroft-Gault) is calculated
The Cockcroft-Gault equation estimates creatinine clearance from age, weight, sex, and serum creatinine. Despite eGFR (CKD-EPI) being preferred for CKD staging, Cockcroft-Gault remains the equation most drug labels and pharmacokinetic dosing nomograms were validated against.
Use actual body weight for normal-weight patients; for obese patients many protocols substitute an adjusted body weight (see the IBW calculator) to avoid overestimating clearance.
Normal values
| CrCl (mL/min) | Interpretation |
|---|---|
| ≥ 90 | Normal |
| 60 – 89 | Mild reduction |
| 30 – 59 | Moderate reduction — dose adjust |
| 15 – 29 | Severe reduction — dose adjust |
| < 15 | Kidney failure |
Clinical use
Primarily used for renally-cleared drug dosing — anticoagulants (e.g. DOACs), antibiotics (e.g. vancomycin, aminoglycosides), and many others specify dose adjustments by Cockcroft-Gault CrCl in their prescribing information. It tends to run slightly higher than measured GFR because creatinine is also actively secreted by renal tubules.
Frequently asked questions
What is creatinine clearance?
Creatinine clearance (CrCl) is an estimate of kidney filtration rate calculated from age, weight, sex, and serum creatinine using the Cockcroft-Gault equation — used mainly to guide renally-cleared drug dosing.
What's the difference between CrCl and eGFR?
Both estimate kidney function, but CrCl (Cockcroft-Gault) is what most drug prescribing information was validated against, while eGFR (CKD-EPI) is the modern standard for staging chronic kidney disease. They can give meaningfully different numbers for the same patient.
What is a normal creatinine clearance?
90 mL/min or above is considered normal. Mild reduction is 60–89, moderate 30–59, severe 15–29, and below 15 indicates kidney failure.
Why is Cockcroft-Gault still used for drug dosing if eGFR is more modern?
Most drug labels and pharmacokinetic dosing nomograms were validated using Cockcroft-Gault CrCl, so switching the reference equation could change the true accuracy of dose recommendations. Regulatory and prescribing guidance hasn't fully transitioned to eGFR-based dosing.
References
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16:31–41.
- FDA Guidance for Industry: Pharmacokinetics in Patients with Impaired Renal Function.