Creatinine Clearance (from 24-hour urine collection)
This test measures how well your kidneys filter waste products, using a 24-hour urine sample. It helps assess kidney function and blood flow to the kidneys.
["A key way to check kidney health and blood flow over a full day."]
Key facts at a glance
- LOINC
- 35991-9
- Short code
- CT Foot
- Synonyms
- CT Foot
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ct
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Matters for Kidney Health
Creatinine clearance is important because it reflects how efficiently your kidneys remove waste from your blood. Unlike a single blood test, this 24-hour method gives a more complete picture of kidney function over time.
How the Test Works
You’ll collect all urine for a full 24-hour period in a special container. Blood and urine samples are sent to the lab to measure creatinine levels. The lab calculates clearance by comparing urine and blood creatinine levels to your body weight.
What to Expect Before the Test
No special preparation is needed, but drink plenty of water to help your kidneys work normally. Avoid diuretics (like caffeine) that may affect urine output. Wear comfortable clothing for easy collection.
What to Expect During the Test
You’ll start by emptying your bladder into the container at the beginning of the 24-hour period. After that, collect all urine—including at night—until you finish at the end of the day. A healthcare provider may remind you to stay hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low creatinine clearance may indicate kidney disease, poor blood flow, or other conditions affecting kidney function. High values could suggest dehydration or overhydration. This test helps doctors diagnose and monitor kidney problems early, especially in people with diabetes, high blood pressure, or a history of kidney issues.
Short name
24-Hour Urine Creatinine Clearance
Frequently asked questions
Why might my doctor order this test?
What do my results mean?
Can I eat or drink anything before the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy