Skip to content

Serum or Plasma Creatinine Concentration (Mass 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 helps check kidney function by measuring waste in your blood."]

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

Key facts at a glance

LOINC
37429-8
Short code
XR tomo Wrist-Bl
Synonyms
XR tomo Wrist-Bl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-tomography
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

Creatinine levels can indicate how well your kidneys are working. High levels may suggest kidney damage or disease, while low levels could indicate dehydration or muscle loss. Your doctor may order this test to monitor kidney health, especially if you have conditions like diabetes, high blood pressure, or a history of kidney problems.

What to Expect Before the Test

You may be asked to fast for a few hours before the test, but this depends on your doctor’s instructions. Bring any medications you’re currently taking. Avoid strenuous exercise or heavy meals before the blood draw.

What Happens During the Test

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause pain. The blood sample is sent to a lab for analysis.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or micromoles per liter (µmol/L). Your doctor will compare your results to your baseline and any symptoms you have to determine if further action is needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine

Frequently asked questions

How often should I get this test?
Your doctor will decide how often to check your creatinine levels based on your overall health, medical history, and any kidney-related conditions. Regular monitoring may be needed if you have chronic kidney disease, diabetes, or high blood pressure.
Can diet affect my creatinine levels?
Yes, diet can influence creatinine levels. High-protein foods (like red meat) may temporarily increase creatinine, but your body usually balances it out. Avoiding excessive protein intake for a few days before testing can help stabilize results. Always follow your doctor’s advice.
What if my results are abnormal?
If your creatinine levels are higher than expected, your doctor may recommend further tests to check kidney function, such as a urine test or imaging studies. If levels are low, they might investigate causes like dehydration, muscle loss, or certain medications. Always discuss your results with your healthcare provider.
  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