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]

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.