Creatinine clearance measures what?

• A. A measure of glomerular function and an indicator for renal disease progression.
• B. The volume of urine produced per day.
• C. A blood test for liver function.
• D. A measurement of electrolyte balance.

Answer: (B)

Creatinine clearance is a test that estimates how well the kidneys’ glomeruli are filtering blood, essentially providing an estimate of the glomerular filtration rate (GFR). It uses both the amount of creatinine in urine over a collection period (usually 24 hours) and the creatinine level in the blood. By calculating how much plasma is cleared of creatinine per minute, it gives a sense of the kidneys’ filtration capacity. This makes it useful for assessing overall renal function and monitoring progression of kidney disease over time.

It’s not simply measuring how much urine is produced in a day. Urine volume is an important observation on its own (urine output), but creatinine clearance relies on the relationship between urine creatinine and serum creatinine to estimate GFR. Also, creatinine clearance is not a liver function test or an electrolyte balance test.