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Creatinine Clearance (24-hour urine collection)

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

This test measures how well your kidneys filter waste products from your blood, using a 24-hour urine sample. It helps assess kidney function and blood pressure management.

Quick summary

["A 24-hour urine test helps doctors check kidney health and blood pressure control."]

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

Key facts at a glance

LOINC
44115-4
Short code
CT Abd+Pelvis
Synonyms
CT Abd+Pelvis
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
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 This Test Is Done

Your doctor may order this test if they suspect kidney disease, evaluate how well your kidneys are working after treatment, or check if your blood pressure medications are working properly. It’s also used to monitor chronic conditions like diabetes or heart disease.

What to Expect Before the Test

You’ll collect all urine for a full 24-hour period (from one morning to the next). Drink plenty of water but avoid diuretics (like caffeine or certain medications) unless instructed otherwise. Store your urine in a clean container and bring it to the lab on time.

How the Test Works

Your urine sample is analyzed to measure creatinine levels, a waste product from muscle metabolism. The test compares how much creatinine is excreted in urine to your blood creatinine levels to calculate clearance, which reflects kidney function.

What the Results Mean

Lower-than-expected clearance may indicate kidney damage or poor filtration, while higher-than-expected results could suggest dehydration or overhydration. Your doctor will interpret results based on your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Urine Creatinine Clearance

Frequently asked questions

How long does a 24-hour urine collection take?
The actual urine collection takes about 24 hours, but you’ll need to plan ahead to remember to start and stop timing correctly. Some patients use timed containers or track their urine output with a diary.
Can I eat or drink normally before this test?
Yes, you can eat and drink as usual, but avoid excessive caffeine or diuretics unless your doctor specifies otherwise. Drinking water helps maintain proper urine volume for accurate results.
What if I miss any urine during the collection?
If you miss urine, your test may be invalid. Your doctor or lab will guide you on how to proceed if this happens, such as retesting or adjusting the collection period.
  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