The creatinine clearance calculator finds the creatinine clearance, which is an estimate of the glomerular filtration rate (GFR). A commonly used creatinine clearance formula is the Cockcroft-Gault equation. In the article, you can learn how the estimate CrCl calculation is conducted and how to find this value directly, using urine creatinine concentration.
What is creatinine clearance?
Creatinine clearance, or CrCl for short, is a measure of renal function. Creatinine clearance rate is the volume of blood plasma that is cleared of creatinine per unit time. It's a convenient method of estimating the patient's GFR.
95 - 160 mL/min is considered to be normal creatinine clearance range.
CrCl or GFR are measured when renal disease is suspected, or when careful dosing of renally metabolized drugs is required. Please note that the recommended way of determining the dosage of drugs for patients with renal failure is based on the calculation of GFR and not CrCl, which can be less accurate. Apart from the Cockcroft-Gault equation, there are four different ways of estimating GFR:
- CKD-EPI Creatinine Equation
- CKD-EPI Creatinine-Cystatin Equation
- CKD-EPI Cystatin C Equation
- MDRD Study Equation
There is a substantial difference in the way that GFR is calculated for adults and for pediatric use.
The Cockcroft-Gault equation
The Cockcroft-Gault equation is named after the scientists, dr. Donald William Cockcroft and dr. Matthew Henry Gault, who first published the formula in 1976. It uses serum creatinine (sCr) measurements and a patient's weight to predict the creatinine clearance estimate in mL/min. The equation looks like this:
CrCl = (140 - age) * weight * sex / (72 * sCr)
The coefficient dependent on the patient's sex is 0.85 for females or 1 for males.
Direct CrCl calculation
Creatine clearance can also be calculated directly, using both serum (sCr) and urine creatinine (uCr), and urine volume. The result is reliable, but it's less popular because of the inconvenient 24-hour collection of urine. You can find this option in our creatinine clearance calculator by clicking
advanced. It uses the creatinine clearance formula:
dCrCl = uCr * urine volume / (sCr * urine collection duration)