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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.

Quick summary

Assesses kidney function by tracking how efficiently waste is removed over a full day.

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

Key facts at a glance

LOINC
36770-6
Short code
CT Guided BDs+GB Drain+cath place
Synonyms
CT Guided BDs+GB Drain+cath place
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 Matters

Creatinine clearance helps doctors evaluate kidney health by measuring how well your kidneys filter waste products like creatinine from your blood. It’s particularly useful for detecting early kidney damage or disease, even if blood tests alone show normal kidney function.

How the Test Works

You’ll collect all your urine over a 24-hour period and provide a blood sample at the start. The lab calculates clearance by comparing the creatinine levels in your urine and blood.

Sample Collection Guidelines

To prepare, empty your bladder before starting. Collect every drop of urine for 24 hours, including at night. Store urine in a clean container and keep it refrigerated until you return it to the lab. Bring both the urine sample and your initial blood sample.

What to Expect

You’ll likely need to stay home for the full 24 hours, as you’ll be collecting urine at home. Bring a clean container, a log to track urine output, and a blood sample on ice. Most labs will provide instructions for proper storage and submission.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low creatinine clearance may indicate kidney disease, poor kidney function, or conditions like heart failure or dehydration. High clearance could suggest overhydration or certain genetic kidney disorders. This test is critical for monitoring chronic kidney disease, kidney transplants, or patients on medications that affect kidney function.

Short name

24-Hour Creatinine Clearance

Frequently asked questions

How long does the 24-hour urine collection take?
You’ll need to complete the collection over a full 24-hour period, including overnight. Most patients can do this at home with proper instructions.
Do I need to fast before this test?
No fasting is required for this test. However, avoid excessive alcohol or certain medications that may affect kidney function before testing.
What if I miss any urine during the collection?
If you miss any urine, your test may be invalid. Follow your lab’s instructions carefully to ensure complete collection.
  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