The creatinine clearance test compares the level of creatinine in urine with the creatinine level in the blood, usually based on assessments of a 24-hour urine sample and a blood sample drawn at the end of the 24-hour period. Clearance is often measured as milliliters/minute (ml/min). Because creatinine is found in stable plasma concentrations, is freely filtered and not reabsorbed, and is minimally secreted by the kidneys, creatinine clearance is used to estimate the glomerular filtration rate (GFR). The GFR in turn is the standard by which kidney function is assessed.

Alternative Names

GFR; Glomerular filtration rate