A laboratory test for estimating glomerular filtration rate of the kidney. Creatinine clearance can be estimated by use of the following formula for males: (140 – age) (body weight in kg)/72 X serum creatinine (mg/dl) For females, the formula is multiplied by 0.85. The normal creatinine clearance is about 125 ml/min. Lower levels reflect renal insufficiency and may influence the excretion of many drugs and toxins from the body.