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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 your recent creatinine level and urine flow.

Quick summary

["Helps assess kidney function and filtering ability over time."]

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

Key facts at a glance

LOINC
35968-7
Short code
CT Elbow-R
Synonyms
CT Elbow-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
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

What Is Creatinine Clearance?

Creatinine clearance is a measure of how effectively your kidneys remove creatinine—a waste product from muscle metabolism—from your blood. Unlike a single creatinine blood test, this test accounts for both your blood creatinine level and your urine output over time, giving a clearer picture of kidney function.

Why Is This Test Done?

Doctors may order creatinine clearance to evaluate kidney health, especially if you have symptoms like fatigue, swelling, or changes in urine output. It’s also used before surgeries, to monitor chronic kidney disease, or to check kidney function in people with diabetes or high blood pressure.

How Is It Performed?

You’ll typically provide a blood sample (serum) and a 24-hour urine collection. Blood is drawn to measure creatinine levels, while urine is collected over 24 hours to measure total creatinine excretion. Results are calculated using your urine volume and creatinine concentration.

What Do Results Mean?

Lower than expected clearance may indicate reduced kidney function, while higher values could suggest overhydration or other conditions. Your doctor will interpret results in relation to your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine clearance is a critical tool for diagnosing and monitoring kidney disease. It helps identify early signs of kidney damage by assessing how well waste products are filtered, which can guide treatment decisions like medication adjustments or lifestyle changes.

Short name

Creatinine Clearance

Frequently asked questions

What causes creatinine clearance to be low?
Low creatinine clearance often signals kidney problems, such as chronic kidney disease, dehydration, or conditions that restrict blood flow to the kidneys. It can also occur with certain medications or severe illness.
What causes creatinine clearance to be high?
High creatinine clearance may result from overhydration, excessive urine output (e.g., from diabetes insipidus), or conditions that increase muscle mass (since creatinine comes from muscle breakdown). Rarely, it could indicate errors in test collection or calculation.
Does diet affect creatinine clearance?
Dietary protein intake can influence creatinine levels, but creatinine clearance itself is primarily based on kidney function and urine flow. High-protein diets may temporarily raise blood creatinine, but the clearance test accounts for this by measuring urine output over time.
  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