Which statement about the constants used in the Cockcroft-Gault equation is correct?

Which statement about the constants used in the Cockcroft-Gault equation is correct?

• A. They are the same for males and females.
• B. They are derived from age.
• C. They are fixed multipliers: 1.23 for males and 1.04 for females.
• D. They change with serum creatinine units.

Answer: (C)

In Cockcroft-Gault, the factors you multiply by are fixed adjustments that reflect sex differences and the unit used for serum creatinine. When serum creatinine is expressed in micromoles per liter, the constants are 1.23 for males and 1.04 for females. These numbers come from converting the original mg/dL version of the equation (which uses a female adjustment of 0.85) into µmol/L, so they remain fixed for that unit system. The age term (140 minus age) and the weight term are separate parts of the calculation, not the constants themselves. If you switch to a different unit for creatinine, you use a different set of constants, which is why the 1.23 and 1.04 values are specifically tied to Scr in µmol/L.

In Cockcroft-Gault, the factors you multiply by are fixed adjustments that reflect sex differences and the unit used for serum creatinine. When serum creatinine is expressed in micromoles per liter, the constants are 1.23 for males and 1.04 for females. These numbers come from converting the original mg/dL version of the equation (which uses a female adjustment of 0.85) into µmol/L, so they remain fixed for that unit system. The age term (140 minus age) and the weight term are separate parts of the calculation, not the constants themselves. If you switch to a different unit for creatinine, you use a different set of constants, which is why the 1.23 and 1.04 values are specifically tied to Scr in µmol/L.