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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 are filtering waste from your blood, using a 24-hour urine sample and your serum creatinine level. It helps assess kidney function over time.

Quick summary

["A 24-hour urine test helps doctors check how well your kidneys are working by tracking waste removal."]

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

Key facts at a glance

LOINC
13553-3
Short code
Cocaethylene SerPl Ql
Synonyms
Cocaethylene SerPl Ql
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 This Test Matters

Kidneys filter waste and excess substances from your blood. Creatinine clearance measures how efficiently this happens. Unlike a single blood test, this method accounts for how much urine you produce over 24 hours, giving a more accurate picture of kidney health.

How It Works

You’ll collect all your urine for 24 hours (starting after your first urine of the day). Blood is drawn to measure serum creatinine. Your doctor calculates clearance by comparing urine creatinine output to your blood creatinine level and urine volume.

What to Expect

You’ll receive instructions to collect every drop of urine for 24 hours. Blood may be drawn at your visit. Follow-up may include a urine sample at the end of the period to confirm completeness.

Preparation

No special prep is needed, but drink plenty of water to help your kidneys work normally. Avoid medications that may affect urine output (ask your doctor).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for diagnosing kidney disease, monitoring chronic conditions (like diabetes or hypertension), or evaluating kidney function before surgery. Low clearance may indicate kidney damage or disease progression.

Short name

CreaClr (24h)

Frequently asked questions

What causes false low results?
Drinking too much water or certain medications (e.g., diuretics) can lower creatinine levels. Incomplete urine collection may also skew results.
What causes false high results?
Muscle disorders, dehydration, or high-protein diets may raise creatinine. Blood in urine or improper timing of blood draw can also affect results.
How often should I get this test?
Your doctor will determine frequency based on your health needs—typically every 6–12 months for stable kidney function or more often if you have kidney disease.
  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