Creatinine and Creatinine Clearance

Blood Creatinine

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Taking medicines, such as methyldopa, trimethoprim (Proloprim, Trimpex), vitamin C (ascorbic acid), cimetidine (Tagamet), some diuretics, and cephalosporin antibiotics, especially cefoxitin (Mefoxin). These affect the blood creatinine levels.
• Taking medicines, such as vitamin C (ascorbic acid), phenytoin (Dilantin), some cephalosporin antibiotics, captopril, aminoglycosides, trimethoprim (Proloprim, Trimpex), cimetidine (Tagamet), quinine, quinidine (Cardioquin, Quinaglute, Quinidex), procainamide, and the antifungal medication amphotericin B. These affect the creatinine clearance levels.
• Taking medicines, such as cimetidine (Tagamet), steroids, and tetracycline antibiotics. These can affect the BUN-to-creatinine ratio.
• Doing strenuous exercise 2 days before creatinine clearance test.
• Eating more than 8 oz (227 g) of meat, especially beef, in the 24 hours before a blood creatinine test and during a creatinine clearance urine test.

Go to previous section	Go to top of page	Go to next section
Author:	Monica Rhodes	Last Updated: August 12, 2008
Medical Review:	E. Gregory Thompson, MD - Internal Medicine Tushar J. Vachharajani, MD, FASN, FACP - Nephrology
© 1995-2009 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.