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Serum or Plasma Creatinine Concentration

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

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood or plasma. It helps assess how well your kidneys are filtering blood.

Quick summary

["A creatinine test helps check kidney function by evaluating how well your kidneys remove waste from your blood."]

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

Key facts at a glance

LOINC
73948-2
Short code
JWH-122 Bld Ql
Synonyms
JWH-122 Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Your Kidneys Matter

Kidneys filter waste and extra fluids from your blood to keep your body balanced. If they don’t work well, waste can build up, which can cause health problems. This test helps doctors see if your kidneys are working as they should.

What the Test Measures

Creatinine is a byproduct of muscle activity. When your kidneys filter blood, they remove creatinine. High levels in your blood may mean your kidneys aren’t working as well as they should.

How the Test Is Done

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine levels.

What the Results Mean

Results can vary based on factors like muscle mass, age, and overall health. Doctors use them along with other tests to diagnose kidney problems or monitor kidney disease.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

What causes creatinine levels to be too high?
High creatinine levels can be caused by kidney problems, such as chronic kidney disease, acute kidney injury, or blockages in the urinary tract. Other factors like severe dehydration, heart failure, or certain medications may also contribute.
What causes creatinine levels to be too low?
Low creatinine levels can occur if you have very little muscle mass, are severely dehydrated, or have conditions like liver disease or malnutrition that affect muscle breakdown.
How often should I get this test?
Your doctor will determine how often you need this test based on your health history, symptoms, and risk factors. People with kidney disease or related conditions may need tests more frequently.
  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