Cockcroft-Gault vs CKD-EPI: which one to use
They answer different questions. Cockcroft-Gault estimates creatinine clearance in mL/min. That's the number on most drug labels and the one you use for dose adjustments. CKD-EPI estimates GFR normalised to 1.73m² body surface area and is what you use for CKD staging and cardiovascular risk.
Using CKD-EPI for drug dosing and Cockcroft-Gault for CKD staging gets you into trouble. Keep them in their lanes.
Body weight selection in obesity
Cockcroft-Gault was validated in patients with normal body habitus. In obese patients (BMI >30), using actual body weight overestimates creatinine clearance for most drugs. IBW (Devine formula) is safer for most renally-cleared drugs. Adjusted body weight (IBW + 0.4 × excess) is used for some agents where partial adipose distribution matters, like aminoglycosides.
Drug dosing by CrCl (Cockcroft-Gault)
| CrCl (mL/min) | CKD Stage | Key dose adjustments |
|---|---|---|
| ≥60 | G1-G2 | Standard doses for most drugs |
| 30-59 | G3 | Reduce: metformin, NSAIDs caution, LMWH |
| 15-29 | G4 | Major reductions: most renally-cleared drugs |
| <15 | G5 | Dialysis dosing: specialist guidance required |
Related tools
For DOAC dose selection by CrCl, see CHA2DS2-VASc Score. For IV antibiotic dosing, see IV Drip Rate Calculator. For weight-based dosing, see Weight-Based Dose Calculator. For converting creatinine units (mg/dL to µmol/L), see Lab Values Converter.
References
- Cockcroft DW, Gault MH. "Prediction of creatinine clearance from serum creatinine." Nephron. 1976;16(1):31-41.
- Inker LA, et al. "New creatinine- and cystatin C-based equations to estimate GFR without race." NEJM. 2021;385(19):1737-1749.
- KDIGO CKD Work Group. KDIGO 2012 Clinical Practice Guideline for CKD. Kidney Int Suppl. 2013;3(1):1-150.