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Creatinine Clearance (from 24-hour urine collection)

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

This test measures how well your kidneys filter waste products, specifically creatinine, over a full day. It helps assess kidney function and blood flow to the kidneys.

Quick summary

["This test helps doctors check how well your kidneys are working and if blood is flowing properly to them."]

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

Key facts at a glance

LOINC
16544-9
Short code
CANRU
Synonyms
Canrenone Ur-aCnc
Category
chemistry
Sample
urine
Container
Sterile urine collection container without preservative; for 24-hour collection, use a large-volume container (2-3 liter) without preservative, kept refrigerated during collection period
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
High-Performance Liquid Chromatography (HPLC) with Mass Spectrometry detection
CPT
83789
SNOMED
395080008
Specimen volume
10 mL random urine aliquot; for 24-hour collection, entire 24-hour volume is submitted with total volume recorded
Stability
Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
48–96 hours
Order
routine

What Does This Test Measure?

Creatinine clearance measures the volume of urine your kidneys produce while filtering creatinine—a waste product from muscle metabolism—over 24 hours. Unlike a single blood test, this method reflects long-term kidney function and blood flow more accurately.

Why Is This Test Important?

This test is useful for diagnosing and monitoring kidney disease, especially in people with diabetes, high blood pressure, or other conditions that may affect kidney function. It helps determine if your kidneys are filtering waste properly and if you need adjustments to medications.

How Is This Test Done?

You’ll collect all urine for a full 24-hour period in a special container. Your healthcare provider will provide instructions to ensure accurate timing. Blood may also be drawn at the start or end of the collection period to help calculate results.

What Are Common Uses?

Doctors use this test to evaluate kidney function in people with symptoms like fatigue, swelling, or frequent urination. It’s also used before surgeries, to monitor chronic kidney disease, and to check if medications are safely cleared by the kidneys.

Reference range

Reference ranges vary by laboratory methodology. Typically not established for random urine; results are often reported as concentration per unit creatinine or as 24-hour excretion. Consult your laboratory's reference guide for specific values.N/A

Specimen: urine

No special patient preparation is required. Patient should follow normal dietary and fluid intake habits unless otherwise instructed by their healthcare provider. For 24-hour collection, instruct patient on proper collection technique.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test plays a critical role in diagnosing and managing kidney disease by providing a detailed picture of how well your kidneys are filtering waste. Unlike a single blood test, it accounts for daily variations in kidney function and blood pressure, offering a more precise assessment of long-term kidney health.

Short name

24-Hour Urine Creatinine Clearance

Frequently asked questions

Why do I need a 24-hour urine test for creatinine clearance?
A 24-hour urine test gives a more accurate picture of your kidney function because it measures how well your kidneys filter waste over a full day, rather than just a single blood sample. This helps doctors detect kidney issues that might not show up in a simpler test.
What should I do to prepare for this test?
Follow your healthcare provider’s instructions carefully. Drink enough water to produce urine throughout the day, but avoid excessive fluid intake that could dilute the results. Collect all urine in a container, including first-morning urine, and discard the first urine of the next day.
Can I take my usual medications during the 24-hour urine collection?
Yes, but check with your doctor first. Some medications (like certain diuretics) may affect urine volume or composition. Your provider will guide you on whether to adjust timing or dosage during the test.
  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