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Creatinine Clearance (Serum-Based, 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 combination of your blood creatinine level and a 24-hour urine sample.

Quick summary

["Assesses kidney function by estimating how efficiently your kidneys remove waste."]

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

Key facts at a glance

LOINC
25638-8
Short code
ECP-mCnc
Synonyms
ECP-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 It’s Done

Your doctor may order this test if they suspect kidney disease, need to monitor kidney function over time, or evaluate how well medications are being cleared from your body. It’s also used before surgeries or procedures that require precise kidney function assessment.

How the Test Works

Blood is drawn to measure creatinine levels, and you’ll collect all urine for 24 hours. The test calculates how much creatinine your kidneys filter daily, helping determine kidney efficiency.

What to Expect

Blood draw is quick and usually done at a lab or doctor’s office. For the urine collection, you’ll need to urinate into a container every time, including first morning and last evening urine. Store urine samples properly to avoid contamination.

Possible Results & Interpretation

Results are compared to standard values based on your age, sex, and body size. Lower than expected values may indicate overhydration or kidney issues, while higher values could suggest dehydration, kidney problems, or reduced blood flow to kidneys.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine clearance is a critical measure for diagnosing and managing chronic kidney disease, acute kidney injury, and assessing the need for dialysis. It helps guide treatment plans, including medication adjustments and monitoring fluid balance.

Short name

Creatinine Clearance

Frequently asked questions

What causes false low or high results?
False low results may occur if you’re dehydrated, have high protein intake, or if the urine collection wasn’t complete. False high results can happen with muscle disorders, high protein diet, or improper urine collection.
How often should I get this test?
Your doctor will determine frequency based on your health needs—typically every few months for stable kidney function or annually if you have chronic kidney disease.
Can I eat or drink anything before this test?
No special diet is needed for the blood draw, but for the urine collection, drink enough water to maintain normal urine flow, but avoid excessive fluid intake that could dilute 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