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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

["Assesses kidney function and blood pressure over 24 hours."]

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

Key facts at a glance

LOINC
36036-2
Short code
MR Kidney-R
Synonyms
MR Kidney-R
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
mr
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 Matters

Creatinine clearance is a key measure of how efficiently your kidneys remove waste from your blood. Unlike a single blood test, this 24-hour urine test provides a more accurate picture of your kidney’s ability to filter waste over time.

How the Test Works

Your urine is collected over 24 hours, and your blood is tested at the start. The test compares the amount of creatinine in your urine to your blood creatinine level to calculate how much waste your kidneys remove.

What to Expect Before the Test

No special preparation is needed, but you’ll need to collect all urine for 24 hours. Drink enough fluids to produce urine consistently, but avoid excessive diuretics or medications that may affect kidney function.

What to Expect During the Test

You’ll provide a 24-hour urine sample (typically in two containers) and a single blood sample. Your healthcare provider will guide you on timing and storage to ensure accuracy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24h CrCl

Frequently asked questions

How long does the 24-hour urine collection take?
The urine collection itself takes 24 hours, but you’ll need to start and stop at the same time each day. Your lab technician will provide clear instructions to ensure accuracy.
Can I take medications during the urine collection?
Yes, but inform your doctor or lab technician about any medications, including over-the-counter drugs or supplements, as some may affect kidney function or urine composition.
What if I miss a urine sample?
If you miss any urine, you’ll need to restart the collection from the next morning. Missing even a small amount can skew results, so follow your lab’s guidelines carefully.
  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