clinical measurement used to estimate renal (kidney function test) function, specifically the filtration rate of the glomeruli (clusters of blood vessels that are the primary filtering structures of the kidney). Creatinine is a chemical end product of creatine metabolism that is removed, or cleared, from blood plasma by glomeruli and is excreted in the urine. The creatinine clearance value is determined by measuring the concentration of endogenous creatinine (that which is produced by the body) in both plasma and urine; the reference value for men is 85–125 millilitres per minute and that for women is 75–115 ml per minute. A low or decreased creatinine clearance level may indicate such conditions as glomerulonephritis (inflammation of the glomeruli; also called Bright's disease (Bright disease)), ureteral obstruction, or pyelonephritis (kidney infection).

Creatinine clearance is a slightly less accurate measure of the glomerular filtration rate than inulin clearance (q.v.) because, unlike inulin, a small amount of creatinine is reabsorbed by the kidney and is not excreted in the urine, thereby being lost to measurement. Difficulties involved in carrying out the inulin clearance procedure, however, render creatinine clearance the more practical clinical measurement with which to assess renal function.