Estimated Creatinine Clearance Rate (eCCr) Using Cockcroft-Gault Formula
A commonly used surrogate marker for estimate of creatinine clearance is the Cockcroft-Gault formula, which in turn estimates GFR in ml/min: It is named after the scientists who first published the formula, and it employs serum creatinine measurements and a patient's weight to predict the creatinine clearance. The formula, as originally published, is:
- This formula expects weight to be measured in kilograms and creatinine to be measured in mg/dL, as is standard in the USA. The resulting value is multiplied by a constant of 0.85 if the patient is female. This formula is useful because the calculations are simple and can often be performed without the aid of a calculator.
When serum creatinine is measured in µmol/L:
- Where Constant is 1.23 for men and 1.04 for women.
One interesting feature of the Cockcroft and Gault equation is that it shows how dependent the estimation of CCr is based on age. The age term is (140 - age). This means that a 20-year-old person (140-20 = 120) will have twice the creatinine clearance as an 80-year-old (140-80 = 60) for the same level of serum creatinine (120 is twice as great as 60). The C-G equation assumes that a woman will have a 15% lower creatinine clearance than a man at the same level of serum creatinine.
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