Creatinine is a waste product formed by the breakdown of a substance (creatine) important for converting food into energy (metabolism). The creatinine is filtered out of the blood by the kidneys and then passed out of the body in urine.

If the kidneys are damaged and can't function normally, the amount of creatinine in the urine decreases while the amount of creatinine in the blood increases.

Current as of: November 14, 2014

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Michael Mallea, MD - Nephrology