Creatinine Clearance Simplified MDRD Formula Calculator


Clearance : ml/mn

What is creatinine clearance?

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.).

Why prescribe creatinine clearance?

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.

MDRD formula (Modification of diet in renal disease)

MDRD formula (Modification of diet in renal disease) makes it possible to estimate the glomerular filtration rate (GFR) from a creatinine level. The laboratory can thus systematically transmit an estimate of the GFR for each creatinine assay, promoting the recognition of renal insufficiency.

The predictive value of MDRD varies according to GFR: acceptable for GFR < 60 ml/min/1.73 m2, the equation underestimates GFR > 60 ml/min/1.73 m2. It is generally superior to that of Cockcroft-Gault (C-G), an advantage to be balanced by the imprecision inherent in the two equations.

For dosage adjustment, the MDRD does not offer any advantage over the C-G: the GFR by MDRD is normalized for 1.73 m2 and must therefore be readjusted to the patient's body surface area for the calculation of the doses of drugs. C-G has the advantage of simplicity and greater user experience.

Usual values: Male = 120 ml/min (+/-20ml/min); Female = 95 ml/min (+/-20ml/min).