J Alasdair Millar1. 1. Medical Department, Southland Hospital, Invercargill, New Zealand. Alasdair.millar@health.wa.gov.au
Abstract
AIMS: To review the derivation of the Cockroft and Gault formula for estimating creatinine clearance from serum creatinine in a historical context. METHOD: The derivation described by Cockroft and Gault was reviewed, and an alternative formula was sought using the data reported in the paper. RESULTS: Cockroft and Gault used 24 hour urine creatinine data expressed as mg/kg body weight and mathematical manipulation of a linear regression equation which introduced body weight as an independent variable into the formula. This involved a circular logic and may have been mathematically invalid. A more logical equation not containing body weight was derived from the data. CONCLUSION: The Cockcroft and Gault formula has been validated by long usage but the derivation appears logically insecure. Nevertheless, its role in estimating renal function at the bedside is established.
AIMS: To review the derivation of the Cockroft and Gault formula for estimating creatinine clearance from serum creatinine in a historical context. METHOD: The derivation described by Cockroft and Gault was reviewed, and an alternative formula was sought using the data reported in the paper. RESULTS: Cockroft and Gault used 24 hour urine creatinine data expressed as mg/kg body weight and mathematical manipulation of a linear regression equation which introduced body weight as an independent variable into the formula. This involved a circular logic and may have been mathematically invalid. A more logical equation not containing body weight was derived from the data. CONCLUSION: The Cockcroft and Gault formula has been validated by long usage but the derivation appears logically insecure. Nevertheless, its role in estimating renal function at the bedside is established.