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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

["Kidney function is key—this test helps track 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
5249-8
Short code
MuV Ab Titr Ser CF
Synonyms
MuV Ab Titr Ser CF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
comp-fix
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 Is Done

Your doctor may order this test if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used to monitor kidney disease, diabetes, or dehydration, or before certain medications or procedures.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before testing if your doctor specifies. Drink plenty of water the day before to help your kidneys work normally.

How the Test Is Performed

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 using a specialized method (likely nephelometry or enzymatic assay).

What the Results Mean

Higher-than-normal levels may signal kidney problems, while lower levels could indicate dehydration or muscle breakdown. Your doctor will compare your results to your baseline and other health factors.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

If your creatinine level is high, it may mean your kidneys aren’t working as well as they should, which can affect other parts of your body. It’s often used alongside other tests to diagnose or monitor kidney disease, including chronic kidney disease or acute kidney injury.
This test is not a standalone diagnosis but a key part of assessing kidney function. Your doctor may also check other markers like blood urea nitrogen (BUN) or urine tests for a full picture.
What if my creatinine level is abnormal?
If your results are higher than expected, your doctor may recommend lifestyle changes (like reducing protein intake or staying hydrated), medications, or further testing to find the cause. If it’s lower, they might investigate if you’ve lost too much fluid or muscle mass.
Can diet affect this test?
Yes! Eating a lot of protein or drinking very little water before the test can raise creatinine levels. If your doctor ordered this test, they’ll give you specific instructions to avoid misleading 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