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24-Hour Urinary Creatinine Clearance

Published: August 9, 2026Updated: August 16, 2026

This test measures how efficiently your kidneys filter waste products, specifically creatinine, over a full day. It helps assess kidney function by comparing creatinine levels in your urine to those in your blood.

Quick summary

["This test helps evaluate kidney health by measuring how well your kidneys filter waste over 24 hours."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
74631-3
Short code
GAG/Creat 24h Ur-Rto
Synonyms
GAG/Creat 24h Ur-Rto
Category
glucose
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order a 24-hour urinary creatinine clearance test to check for kidney problems, such as chronic kidney disease, or to monitor kidney function before or after treatments like certain medications or surgeries. It can also help diagnose conditions affecting blood flow to the kidneys or determine how well dialysis is working.

How Is the Test Performed?

You’ll collect all urine for a full 24-hour period in a special container. Your doctor will provide instructions on timing and storage. Blood may also be drawn at the start or end of the collection period to measure baseline creatinine levels.

What Does the Test Result Mean?

Results are typically expressed in milliliters per minute (mL/min) or milliliters per hour (mL/hr). Lower than expected values may indicate kidney damage, while higher values could suggest overhydration or other conditions affecting urine output.

Common Causes of Abnormal Results

Abnormal results may be due to kidney disease, dehydration, high blood pressure, diabetes, or conditions affecting blood flow to the kidneys. Your doctor will discuss these findings with you during your follow-up.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

None

Frequently asked questions

What might cause false or misleading results?
False results can occur if urine isn’t collected correctly (e.g., incomplete collection, contamination), if you’re dehydrated or overhydrated, or if you have certain medications (e.g., diuretics). Always follow your doctor’s instructions precisely for accurate results.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition, symptoms, or treatment plan. Regular tests may be recommended for people with chronic kidney disease or those at higher risk.
Can I eat or drink anything before the test?
No special diet or restrictions are needed for the 24-hour urine collection itself, but follow your doctor’s instructions regarding fluids and medications. Blood draws may have specific fasting requirements.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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