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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 or plasma. It helps assess how well your kidneys are filtering blood.

Quick summary

["A creatinine test is key for checking kidney function."]

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

Key facts at a glance

LOINC
5158-1
Short code
EBV VCA IgG Titr Ser IF
Synonyms
EBV VCA IgG Titr Ser IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82977
SNOMED
3110003
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 Matters for Kidney Health

Creatinine is a byproduct of muscle breakdown and is naturally filtered out by your kidneys. If your kidneys aren’t working well, creatinine builds up in your blood. This test helps doctors determine if your kidneys are functioning properly and identify early signs of kidney disease.

How the Test Works

Your blood or plasma is collected in a lab and analyzed to measure creatinine levels. The test typically uses a method like enzymatic or nephelometric techniques to detect the substance.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a larger kidney function panel. Drink plenty of fluids the day before to help your kidneys work normally.

Possible Results and Their Meaning

Higher-than-normal creatinine levels may suggest kidney problems, while lower levels could indicate dehydration or muscle loss. Your doctor will compare your results to your baseline and other health factors to interpret them accurately.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

What could cause abnormal creatinine levels?
Abnormally high creatinine levels may indicate kidney disease, dehydration, or conditions that reduce blood flow to the kidneys. Low levels might suggest dehydration, low muscle mass, or overhydration. Always discuss results with your healthcare provider.
Can diet affect creatinine levels?
Dietary protein intake can influence creatinine levels, but the test itself measures the waste product from muscle metabolism. Your doctor may consider your diet when evaluating results, especially if you have kidney concerns.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status, kidney function, and any ongoing conditions. Regular monitoring may be recommended if you have diabetes, high blood pressure, or a history of kidney issues.
  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