How does a creatinine clearance test differ from a serum creatinine test?

The key difference between a creatinine clearance test and a serum creatinine test is the collection method and what they measure. A serum creatinine test only requires a blood sample to measure the amount of creatinine in your blood at a single point in time, while a creatinine clearance test requires both a blood sample and a 24-hour urine sample to evaluate how well your kidneys filter creatinine over time. The clearance test provides a more detailed analysis of kidney function.