Creatinine Clearance (Cockcroft-Gault)

Cautions

• An estimate of creatinine clearance, not a measured value. The serum creatinine should reflect a steady state of renal function; the estimate is unreliable while kidney function is changing quickly.
• The tool applies the equation to the numbers entered, in kg and mg/dL, and does not convert units. Check the units on the laboratory report before entering the creatinine.
• The tool is limited to adults (18 years or older). It gives no category and no dosing advice; drug labels state which measure of renal function to use for dose adjustment.
• Creatinine-based estimates depend on muscle mass. In people with little muscle (sarcopenia, long bed rest, marked emaciation, limb amputation, thin older adults) they overestimate kidney function, and in people with a lot of muscle, such as athletes, they underestimate it. In obese people the Cockcroft-Gault estimate overestimates kidney function. When muscle mass is not typical, consider an equation based on cystatin C.
• The Cockcroft-Gault equation was derived with serum creatinine measured by the Jaffe method. Enzymatic and Jaffe measurements differ somewhat, so a value from a different assay can shift the estimate.
• The result is a creatinine clearance in mL/min and is not adjusted for body surface area. It is not the same quantity as an eGFR from another equation.