By Naomi Foster, health writer. Last updated .
How Is Creatinine Clearance Calculated
The Cockcroft-Gault equation estimates how quickly the kidneys clear creatinine from the blood. It uses age, body weight, sex, and serum creatinine, and is still widely used as a reference for kidney function and drug dosing, decades after it was first published.
For example, a 60-year-old male weighing 70 kg with a serum creatinine of 1.0 mg/dL gives CrCl = ((140 - 60) x 70 x 1) / (72 x 1.0) = 5600 / 72, which is about 78 mL/min. Swap in the female sex factor and the same inputs land closer to 66 mL/min, since 0.85 shrinks the result rather than the age or weight terms changing.
| Sex | Factor (F) |
|---|---|
| Female | 0.85 |
| Male | 1.00 |
Source
The equation was published by Cockcroft DW and Gault MH, "Prediction of creatinine clearance from serum creatinine" (Nephron, 1976). For background on kidney function tests, see the National Kidney Foundation and NIDDK: Kidney Disease.
Things to Know Before Using Cockcroft-Gault
Cockcroft-Gault can be less accurate at the extremes of body weight, in older adults, in pregnancy, and when serum creatinine is changing quickly. The choice of body weight, actual, ideal, or adjusted, affects the result and is a clinical decision, usually made by the prescribing clinician or a pharmacist rather than by this page.
Some hospital pharmacies still prefer Cockcroft-Gault over newer eGFR equations for dosing specifically because more of the original drug-dosing studies were built around it. That history is a reason the formula persists in dosing software even though estimating equations have moved on elsewhere in nephrology.