Skip to content

Creatinine Clearance (from Serum)

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

This test measures how well your kidneys filter waste products from your blood, using creatinine levels in your serum. It helps assess kidney function and blood flow to the kidneys.

Quick summary

["A key measure of kidney health and blood flow efficiency."]

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

Key facts at a glance

LOINC
35965-3
Short code
CT Elbow-Bl
Synonyms
CT Elbow-Bl
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 It Matters in Kidney Health

Creatinine clearance is a critical test for evaluating kidney function because creatinine is a waste product naturally produced by muscle metabolism. Healthy kidneys filter this waste efficiently, so measuring how well they do so helps doctors detect early signs of kidney damage or disease.

How the Test Works

Your blood is drawn to measure creatinine levels. Alongside this, urine is collected over a 24-hour period to measure creatinine excretion. The test calculates how much creatinine is filtered by the kidneys by comparing the blood and urine levels.

When You Might Need This Test

Doctors may order creatinine clearance if you have symptoms like swelling, fatigue, or frequent urination; if you have a history of kidney disease, diabetes, or high blood pressure; or if you’re undergoing treatment that could affect kidney function.

What to Expect Before the Test

No special preparation is needed, but you should avoid strenuous exercise or heavy meals 24 hours before the test. Drink plenty of water on the day of testing to support kidney function and urine flow.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine Clearance

Frequently asked questions

What does a low creatinine clearance mean?
A lower than expected creatinine clearance may indicate reduced kidney function, which could be due to kidney disease, dehydration, or other conditions affecting blood flow to the kidneys. It’s important for monitoring chronic kidney disease and guiding treatment plans.
What does a high creatinine clearance mean?
A higher than expected creatinine clearance is less common but may suggest overhydration or conditions that increase blood flow to the kidneys. It’s usually not a cause for concern unless accompanied by other symptoms or medical history.
How often should I get this test?
Your doctor will determine how often you need this test based on your overall health, medical history, and any kidney-related conditions. Regular monitoring may be recommended if you have chronic kidney disease, diabetes, or high blood pressure.
  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