Creatinine Clearance (24 Hour Urine and Blood)


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Quest Diagnostics Test Code: 7943

Blood creatinine level is measured as a test of kidney function to estimate the glomerular filtration rate (GFR), the rate of blood flow through the kidneys.

Creatinine is a waste product that is produced by the muscles during energy production and respiration and is removed by the kidneys, which filters almost all of it from the blood to be excreted in the urine. Creatinine clearance measures the creatinine levels from both a 24 hour urine sample and a blood sample. Creatinine and creatinine clearance are one of the most important tests used to determine kidney function and along with other kidney tests can help in the diagnosis of specific kidney disease of diseases which eventually affect the kidneys, such as diabetes and high blood pressure.

This test is performed in following conditions such as:

• Fatigue, lack of concentration, poor appetite, or trouble sleeping
• Swelling or edema
• Abnormal urine color
• A decrease in the amount of urine
• Burning or pain on urination
• Mid back pain
• High blood pressure


The Creatinine Clearance (24-hour Urine and Serum) test is both a blood and urine collection. The blood test has no fasting requirements but is preferably collected at the time the urine collection is completed. The blood collection must be done no more than 24 hours after the end of the urine collection. The Creatinine, 24-hour Urine test requires people void urine at 8am and discard the specimen. Then collect all urine in 24-hour period, ending with final collection at 8am the next morning. It is important to stay hydrated during the period of specimen collection. Exercise should be avoided prior to and during the period of specimen collection. Certain medications may interfere with the results of this test. Customers should connect with a prescribing physician to determine if they should stop taking medication prior to specimen collection.


Specimen Collected
  • Blood
  • Urine
Estimated Time Taken

Turnaround time for the Creatinine Clearance test is typically 1-3 business days.