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Serum Creatinine (Creatinine Level)

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

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood. It helps assess kidney function.

Quick summary

["Kidney health depends on this simple blood test."]

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

Key facts at a glance

LOINC
43540-4
Short code
Deprecated Finger.5th-R XR GE 3V
Synonyms
Deprecated Finger.5th-R XR GE 3V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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?

Creatinine is a byproduct of muscle breakdown that your kidneys normally filter out of your blood. High levels may indicate impaired kidney function, while low levels could suggest muscle loss or other conditions.

Why Is This Test Done?

Doctors order creatinine tests to monitor kidney health, especially in people with diabetes, high blood pressure, or a history of kidney disease. It’s also used to evaluate kidney function after certain treatments or injuries.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis. No special preparation is needed, but fasting may be advised in some cases.

What Do Results Mean?

Results are compared to a general reference range, but individual ranges can vary by lab. Elevated levels may signal reduced kidney function, while persistently low levels could warrant further investigation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

Why might my creatinine test be done regularly?
Regular creatinine testing helps track kidney function over time, especially if you have conditions like diabetes, heart disease, or hypertension that can affect kidneys. Your doctor may also recommend it after surgery or if you’re taking medications that could impact kidney health.
What could affect my creatinine test results?
Several factors can influence results, including dehydration, muscle mass, certain medications, or recent exercise. If you’re unsure about your preparation, discuss it with your healthcare provider.
Do I need to prepare for this test?
Most people don’t need special preparation, but your doctor may advise fasting or avoiding certain foods/drinks. Always follow their instructions to ensure accurate 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