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Serum or Plasma Creatinine Concentration (Substance Concentration)

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 how well your kidneys are filtering blood.

Quick summary

["Kidney function and waste removal depend on this test."]

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

Key facts at a glance

LOINC
6492-3
Short code
N men Ag Spec Ql IF
Synonyms
N men Ag Spec Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 Used For?

Creatinine levels help doctors evaluate kidney function by checking how well your kidneys remove waste from your blood. It’s often used alongside other tests to diagnose or monitor kidney disease.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms like swelling, fatigue, or changes in urine output, or if you have conditions like diabetes, high blood pressure, or a family history of kidney problems.

How Is the Test Done?

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

What Are Common Results?

Results are compared to a general reference range to determine if your kidneys are functioning normally or if further action is needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels can indicate kidney function, but they’re not the only measure. High levels may signal kidney damage, while very low levels could suggest muscle loss or other health issues.

Short name

Creatinine

Frequently asked questions

Why do some people need repeated creatinine tests?
Repeated tests may be needed if you have chronic kidney disease, are taking medications that affect kidney function, or if your health changes over time. Your doctor will decide the timing based on your needs.
Can diet affect creatinine levels?
Dietary changes like eating more protein can temporarily affect creatinine levels, but your doctor will consider overall health and kidney function when interpreting results.
What happens if my creatinine level is high?
High levels may signal kidney problems and could require further testing or treatment to manage kidney health. Your doctor will discuss next steps based on your 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