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Creatinine Clearance (24-Hour Urine)

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

This test measures how well your kidneys filter waste products from your blood over a 24-hour period by analyzing your urine and blood samples. It helps assess kidney function and blood flow to the kidneys.

Quick summary

["A 24-hour urine test helps doctors check how well your kidneys are working by tracking waste removal over time."]

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

Key facts at a glance

LOINC
69245-9
Short code
Deprecated RF Kidney PC Bx needle guide
Synonyms
Deprecated RF Kidney PC Bx needle guide
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
rf
CPT
86430
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 Is This Test Done?

Your doctor may order this test if they suspect kidney disease, monitor kidney function in chronic conditions (like diabetes or hypertension), or evaluate kidney function before certain procedures. It’s also used to check for proper kidney function in people with high blood pressure or heart disease.

How Is This Test Performed?

You’ll collect all urine for 24 hours in a special container. At the start and end of the period, your doctor will take a blood sample to measure creatinine levels. The urine sample is then sent to a lab for analysis.

What Do the Results Mean?

Results are typically expressed in milliliters per minute (mL/min) or milliliters per hour. Lower than expected results may indicate kidney problems, while higher results could suggest dehydration or other conditions affecting fluid balance.

Common Causes of Abnormal Results

Low creatinine clearance might mean your kidneys aren’t filtering waste properly, possibly due to kidney disease, blockages, or other health issues. High values could signal dehydration, heart failure, or conditions that reduce blood flow to kidneys.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Urine Creatinine Clearance

Frequently asked questions

What should I expect before my test?
No special preparation is needed, but drink enough water to maintain normal urine flow. Avoid excessive alcohol or diuretics (like caffeine) 24 hours before testing, as they may affect results.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on lab processing times. Your doctor will discuss them with you during your follow-up visit.
Can I take my medications as usual before this test?
Yes, unless instructed otherwise by your doctor. Some medications (like certain diuretics) may affect urine output, so always follow your healthcare provider’s guidance.
  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