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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 creatinine levels in your serum and urine.

Quick summary

["Creatinine clearance helps assess kidney function and identify potential kidney damage early."]

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

Key facts at a glance

LOINC
36058-6
Short code
CT Sacrum
Synonyms
CT Sacrum
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 Is This Test Done?

Your doctor may order this test to evaluate kidney function, especially if you have symptoms like fatigue, swelling, or changes in urine output. It’s also used before surgeries, during pregnancy, or if you have conditions like high blood pressure or diabetes that can affect kidney health.

How Is the Test Performed?

You’ll provide a blood sample (serum) and a 24-hour urine collection. The blood test measures creatinine levels, while the urine test measures creatinine and urine volume over 24 hours. The results are compared to calculate how efficiently your kidneys filter waste.

What Do the Results Mean?

Lower than expected clearance may indicate kidney problems, while higher values could suggest dehydration or overhydration. Your doctor will interpret results in relation to your overall health and symptoms.

Common Reasons for Testing

This test is often used to monitor kidney function in chronic conditions, screen for early kidney disease, or guide treatment decisions for conditions like hypertension or diabetes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Clearance

Frequently asked questions

What is creatinine clearance, and how does it differ from a simple blood creatinine test?
Creatinine clearance measures how well your kidneys filter creatinine—a waste product from muscle metabolism—from blood over 24 hours. A simple blood creatinine test only measures the creatinine level in your blood, which can be influenced by muscle mass, hydration, or other factors. Clearance provides a more comprehensive view of kidney function.
Does fasting affect this test?
No, fasting is not required for this test. The 24-hour urine collection focuses on measuring urine volume and creatinine output, not blood levels. However, hydration status can affect results, so staying well-hydrated but not overhydrated is important.
Can I take medications before this test?
Most medications can be taken as usual unless instructed otherwise. Some medications (like certain diuretics or contrast dyes) may temporarily affect kidney function or urine output, so always check with your doctor before the test.
  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