The original Cockcroft-Gault (1976) equation utilizes an "ideal body weight", or IBW, in order to estimate glomerular filtration. This equation, from the Devine 1974 paper,1 has since undergone scrutiny for poor accuracy in calculating creatinine clearance via Cockcroft-Gault.
Although there are numerous methods to determine the most accurate weight for the Cockcroft-Gault equation, this calculator is capable of using the following formulas:
- Adjusted body weight: If the patient is more than 30% above their IBW (using Devine 1974), the following adjustment is made: Adjusted = 0.4*(Actual-Ideal)+Ideal
- Ideal body weight (Devine 1974): Originally developed for gentamicin dosing, this equation has become the standard method of calculating ideal body weight for adults
- Lean body weight 2005 (Janmahasatian 2005): By far the newest method for calculating "lean body weight", rather than "ideal" body weight, which may better correlate to the most optimal weight to use in the Cockcroft-Gault equation. This equation does not require an additional adjustment for obesity because obesity is "built-in" to the equation.
For more information, please see the 'References and Additional Reading' section at the bottom of the page.