Creatinine Clearance Calculator

What is Measured Creatinine Clearance?

Creatinine clearance (CrCl) is a measure of kidney function that estimates the volume of blood plasma that is cleared of creatinine per unit of time. It is calculated from the creatinine concentration in a collected urine sample (usually over 24 hours), the urine volume, and the serum creatinine concentration.

While estimating equations (like CKD-EPI) are more common, a measured 24-hour collection can be more accurate in certain populations, such as individuals with extreme muscle mass or diet.

Why Perform a 24h Collection?

• Provides a direct measurement of creatinine excretion, rather than an estimation.
• Can be more accurate in patients with malnutrition, amputation, or vegan diets where estimations may be less reliable.
• Often considered a gold standard for determining appropriate drug dosing for nephrotoxic medications.

Interpreting the Result (CKD Stages)

Accuracy and Considerations

The accuracy of this test is highly dependent on a complete and correctly timed 24-hour urine collection. Incomplete collections are a common source of error.

• Start the collection by emptying the bladder and discarding the first urine sample.
• Collect every drop of urine for the next 24 hours in the provided container.
• Keep the collection container refrigerated during the 24-hour period.
• A blood sample for serum creatinine should be drawn during the collection period.