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Urine Creatinine-to-Creatinine Clearance Ratio (24-hour urine collection)

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

This test measures how well your kidneys filter waste products by comparing creatinine levels in your urine and blood over 24 hours. It helps assess kidney function and blood flow.

Quick summary

["This test evaluates kidney efficiency in filtering waste over a full day’s urine output."]

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

Key facts at a glance

LOINC
25154-6
Short code
Unident Crys #/area UrnS HPF
Synonyms
Unident Crys #/area UrnS HPF
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light-hpf
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 This Test Is Done

Your doctor may order this test if you have symptoms like frequent urination, swelling, fatigue, or if they suspect kidney disease, diabetes, or heart conditions. It’s also used to check kidney function in people with high blood pressure or chronic illnesses.

How the Test Works

You’ll collect all urine for 24 hours in a special container. Blood is drawn once to measure creatinine levels. The urine and blood samples are sent to a lab to calculate the ratio of creatinine in urine to blood, adjusted for urine volume.

Sample Collection Process

Start collecting urine immediately after waking up (discard the first void). Continue collecting every time you urinate for 24 hours. Store urine in a cool place. On the 24th hour, collect the last urine sample and add it to the container. Blood is drawn at any time during this period.

What to Expect Before the Test

No special preparation is needed for the urine collection, but drink enough water to maintain normal urine flow. Avoid excessive alcohol or diuretics (like caffeine) that could affect urine volume.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine Cr Clearance

Frequently asked questions

How long does the urine collection take?
The urine collection itself lasts about 24 hours, but you’ll need to plan ahead to ensure you don’t miss any urine samples. Blood draw is quick and typically takes a few minutes.
Can I eat or drink normally before the test?
Yes, you can eat and drink as usual, but avoid excessive fluids that might dilute your urine (like large amounts of water) unless your doctor advises otherwise.
What if I miss a urine sample during the 24-hour period?
If you miss any urine sample, you’ll need to restart the collection from the next morning. It’s important to complete the full 24-hour period for accurate results.
  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