Serum Creatinine-to-Creatinine Clearance Ratio (Creatinine Clearance)

What Does This Test Measure?

Creatinine is a waste product naturally produced by your muscles when they break down proteins. Kidneys filter this waste from your blood and remove it from your body through urine. This test calculates how well your kidneys are removing creatinine from your blood by comparing creatinine levels in serum to an estimated urine flow rate.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms of kidney problems (like swelling, fatigue, or frequent urination), if you have a history of high blood pressure or diabetes, or if you’re taking medications that can affect kidney function.

How Is This Test Done?

A blood sample is taken from a vein in your arm, and a urine sample may be collected (though clearance is estimated rather than measured directly). The test measures creatinine levels in serum and uses standard formulas to estimate kidney function.

What Are Common Causes of Abnormal Results?

Low results may indicate overestimation of kidney function or errors in urine collection. High results could suggest kidney damage, dehydration, or conditions like chronic kidney disease or severe muscle breakdown.