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Serum Creatinine (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 kidney function.

Quick summary

Kidney health check: creatinine levels help detect early kidney problems.

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

Key facts at a glance

LOINC
92959-6
Short code
P aeruginosa DNA Spt NAA+non-prb-NCncRng
Synonyms
P aeruginosa DNA Spt NAA+non-prb-NCncRng
Category
chemistry
Sample
sputum
Container
Sterile sputum container
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
non-probe-amp-tar
CPT
85610
SNOMED
396252006
Specimen volume
3-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
TAT
4–24 hours
Order
routine

What Is Creatinine?

Creatinine is a byproduct of muscle breakdown. Your kidneys normally filter it from your blood and remove it from your body through urine. High levels can indicate kidney issues, while low levels may suggest dehydration or muscle loss.

Why Is This Test Done?

Doctors order creatinine tests to monitor kidney function, especially in people with diabetes, high blood pressure, or a history of kidney disease. It’s also used to assess kidney function before certain procedures or medications.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed for creatinine concentration using an automated method.

What Do Results Mean?

Results are compared to a reference range (not provided here) to determine if your kidneys are working as expected. Abnormal results may prompt further testing or adjustments to treatment.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: sputum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Health

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
This test is typically done as part of a routine health check or if you have symptoms like swelling, fatigue, or changes in urine. Your doctor will decide how often based on your health status.
What if my results are high?
High creatinine levels may signal kidney problems, but they can also be caused by dehydration, muscle injury, or certain medications. Your doctor will discuss next steps, which may include more tests or lifestyle changes.
Can diet affect this test?
Yes, high-protein foods or dehydration can temporarily raise creatinine levels. Your doctor may recommend dietary adjustments or timing your test after a normal meal to get 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