Creatinine clearance measures the ratio between the rate of elimination of creatinine by the kidneys (through urine) and its concentration in the blood. Since creatinine is eliminated only by renal filtration, the measurement of its clearance makes it possible to evaluate the filtration rate of the kidneys. In the evaluation of clearance, the interpretation should take into account age, sex, weight, height, cardiac and renal function, and drug treatment (salicylates, cimetidine, trimethoprim, probenecid, etc.).
Creatinine clearance is prescribed when the kidney disease is suspected, before prescribing medications that involve having normal kidney function, and when renal blood flow is reduced due to heart disease.
This examination can also be requested after an initial blood test showing high blood creatinine.
Usual values: Male= 120 ml/min (+/-20ml/min); Female= 95 ml/min (+/-20ml/min).
The CKD-EPI (Chronic Kidney Disease - Epidemiology Collaboration) equation is more precise than that of the MDRD and should replace the latter in routine clinical use. It is more correct for creatinine clearance values exceeding 60 ml/min/1.73m2.