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Serum or Plasma 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 how well your kidneys are filtering blood.

Quick summary

["Kidney function check: High levels may signal kidney problems; low levels could indicate dehydration or muscle breakdown."]

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

Key facts at a glance

LOINC
69020-6
Short code
LPT PW/CD3 NFr Bld FC
Synonyms
LPT PW/CD3 NFr Bld FC
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
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
flow-cytometry
CPT
85610
SNOMED
396252006
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

Your kidneys filter waste and excess substances from your blood, including creatinine. This test helps doctors check if your kidneys are working properly by measuring how well they remove creatinine from your bloodstream.

What to Expect Before the Test

No special preparation is needed unless instructed by your doctor. You may have a small needle inserted into your arm to draw blood. If you’re on dialysis or have certain conditions, your doctor may advise extra precautions.

Common Causes of Abnormal Results

High creatinine levels might suggest kidney disease, dehydration, or conditions that reduce blood flow to the kidneys. Low levels could indicate dehydration, severe muscle loss, or overhydration.

What Your Results Mean

Your results will be compared to a reference range provided by your lab. While ranges vary by lab, doctors use them to guide next steps, such as further kidney tests or adjustments to medications.

Reference range

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

Specimen: whole-blood

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

Why do doctors order this test?
Doctors often check creatinine levels to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used to assess kidney function before surgeries or during chronic conditions like diabetes or heart disease.
Can diet affect this test?
Yes! High-protein foods or muscle breakdown (e.g., from illness or injury) can temporarily raise creatinine levels. Avoid excessive protein intake 24 hours before testing if your doctor advises it.
Is there any risk with this blood test?
Minimal risk: You might feel slight discomfort from the needle, but reactions are rare. If you’re on blood thinners or have bleeding disorders, let your doctor know before the test.
  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