Creatinine clearance

[helena smith]

Should you use ideal body weight to calculate creatinine clearance (and drug dosing) if the patient is overweight or obese?

[pharout]

Originally Posted by helena smith

Should you use ideal body weight to calculate creatinine clearance (and drug dosing) if the patient is overweight or obese?

The answer is yes, but if a patient is >30% more than their ideal bw (which many in the U.S. are), you should use an "adjusted bw" or "dosing wt". This has also been advocated by our nephrology folks that I work with. The formula for this is: ideal bw+ 0.4 (actual bw-ideal bw). Just plug the kg into the Cockcroft-Gault equation and use. Also if it is an elderly patient (and their Cr is low due to decreased muscle mass), the serum creatinine should be rounded to 0.9mg/dL. I was taught round to 1.0, others say 0.8. Nephrology feels that rounding to 1.0 would be an overcompensation for their true renal function and states 0.9 would be a better compromise.