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Creatinine, 24-Hour Urine

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

Measures the total creatinine excreted in urine over 24 hours. This test can help assess kidney function and check the completeness of a 24-hour urine collection.

Quick summary

["A 24-hour urine creatinine test measures how much creatinine your kidneys excrete and may help evaluate kidney function."]

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

Key facts at a glance

LOINC
56668-7
Short code
AAA/Creat 24h Ur-Rto
Synonyms
AAA/Creat 24h Ur-Rto
Category
liver
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

What is this test?

This test measures the amount of creatinine in all urine collected over a 24-hour period. Creatinine is a waste product produced by muscle metabolism and filtered by the kidneys.

Why might I need this test?

It may be used to assess kidney function, monitor people with kidney disease, or measure how much protein is being lost in the urine. It can also help determine whether a 24-hour urine collection was complete.

How is the test performed?

You usually collect all urine for exactly 24 hours, beginning after emptying your bladder and ending with the final collection. The urine volume and creatinine amount are then measured in the laboratory.

How do I prepare for the test?

Follow your clinician's collection instructions carefully, including the start and stop times and whether the container should be refrigerated. Record the total urine volume if requested, and mention medications, supplements, pregnancy, or unusually heavy muscle activity to your clinician.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A low creatinine amount may occur with reduced kidney filtration, very low muscle mass, or an incomplete collection. A high amount may reflect increased muscle mass or muscle breakdown, while an incomplete collection can make the result misleading.

Short name

24-hour urine creatinine

Frequently asked questions

Do I need to fast for a 24-hour urine creatinine test?
Fasting is usually not required, but follow any specific instructions from your clinician. Unusually strenuous exercise can temporarily increase creatinine levels.
How should I collect the urine?
Collect every drop of urine during the full 24-hour period, using the provided container and refrigeration if instructed. Record the start time, end time, and total collected volume.
Can this test be used by itself to diagnose kidney disease?
No. Results are interpreted with other kidney tests, symptoms, medical history, and sometimes urine protein measurements.
  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