What is the typical unit for creatinine clearance?

• A. mL/min
• B. mg/dL
• C. L/hr
• D. μmol/L

Answer: (A)

Creatinine clearance is a measure of how well the kidneys are filtering creatinine from the blood, essentially an estimate of the glomerular filtration rate. Because it represents a volume of plasma cleared of creatinine per unit time, the appropriate unit is a rate of volume per time. The standard unit used is milliliters per minute (mL/min). Other units shown in the choices describe concentration (mg/dL or μmol/L) or a different time scale (L/hr), which do not represent a clearance rate. Sometimes clearance is reported normalized to body surface area as mL/min/1.73 m^2, but the typical, unnormalized form is mL/min.