CrCl versus eGFR
They answer slightly different questions. eGFR normalizes to a standard body surface area for staging kidney disease; creatinine clearance estimates absolute clearance, which is what matters when deciding how fast a drug leaves the body.
- • Use eGFR for CKD staging, CrCl for renal drug dosing unless the label says otherwise.
- • Cockcroft-Gault overestimates in obesity when actual body weight is used.
- • Neither is valid during acute kidney injury when creatinine is still changing.
FAQ
Which weight should I use in Cockcroft-Gault?
Ideal body weight for most patients, adjusted body weight when actual weight exceeds 130% of ideal, and actual weight if it falls below ideal. This tool selects automatically.
Is creatinine clearance the same as GFR?
Close but not identical. Creatinine is both filtered and secreted by the tubules, so clearance slightly overestimates true GFR.
Why do drug labels still use Cockcroft-Gault?
Most renal dosing studies were conducted using it, so regulators kept the labeling consistent with the original evidence.
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