Creatinine Clearance (Cockcroft-Gault)
Estimates CrCl for drug dose adjustments
Calculator
Why use it
Most drug prescribing information and pharmacokinetic studies use Cockcroft-Gault for renal dose adjustments. It is the preferred equation when adjusting doses for renally cleared medications.
About
The Cockcroft-Gault equation estimates creatinine clearance (CrCl) from serum creatinine, age, weight, and sex. Although not a true GFR measurement, it remains the standard for drug dose adjustments as most pharmacokinetic studies used this formula. It tends to overestimate GFR in obese patients and should use adjusted body weight in that population.
When to use
- Drug dose adjustment for renally cleared medications
- Assessment of renal function in elderly patients
- Anticoagulant dosing (DOACs, enoxaparin)
- Antibiotic dose adjustment (vancomycin, aminoglycosides)
Formula
Pearls & pitfalls
- Cockcroft-Gault is NOT recommended for CKD staging — use CKD-EPI eGFR for that purpose.
- In obese patients (>130% IBW), use adjusted body weight to avoid overestimation.
- Creatinine-based equations are unreliable in AKI, muscle wasting, extremes of age, and amputees.
- The equation assumes stable creatinine — do not use in rapidly changing renal function.
- In elderly patients with very low muscle mass, a "normal" creatinine may mask significant renal impairment.
Next steps
Use CrCl value to adjust medication doses per drug labeling. Consider using adjusted body weight for obese patients (ABW = IBW + 0.4 × [TBW − IBW]). For CKD staging, prefer CKD-EPI equation instead.
Evidence
Original derivation in 249 male patients. Validated extensively over decades. Remains FDA-preferred for pharmacokinetic labeling despite known limitations in extremes of body weight.