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Serum or plasma concentration of creatinine

Published: August 9, 2026Updated: August 17, 2026

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

Quick summary

["A creatinine test helps doctors check how well your kidneys are filtering blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
36788-8
Short code
MRA Neck vv
Synonyms
MRA Neck vv
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
mr-angio
CPT
82553
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 Is Done

Doctors may order a creatinine test to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used before certain procedures or medications to ensure your kidneys are functioning properly.

What to Expect Before the Test

You may be asked to fast for a few hours before the test, but this isn’t always required. Bring any medications you’re taking to your appointment. Avoid strenuous activity the day before.

How the Test Works

A small blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine levels. The result helps determine how well your kidneys are working to filter waste from your blood.

What the Results Mean

Higher-than-normal levels may indicate kidney problems, while lower levels could suggest dehydration or muscle breakdown. Your doctor will interpret results in relation to your overall health and medical history.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
Your doctor will determine the frequency based on your health needs. Some people get it yearly, while others may need it more often if they have kidney-related conditions.
What can affect my creatinine test results?
Factors like dehydration, muscle mass, or certain medications can influence results. Always inform your doctor about all medications, supplements, or recent changes in health.
Is there anything I should avoid before the test?
Avoid excessive alcohol or high-protein meals the day before, as they may impact results. Follow your doctor’s specific instructions for the best accuracy.
  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 17, 2026. · Read our editorial policy