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Serum or Plasma Creatinine Concentration (Standard Method)

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 by checking how well your kidneys filter blood.

Quick summary

["Kidney function check: creatinine levels help determine how well your kidneys are working."]

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

Key facts at a glance

LOINC
38866-0
Short code
XR Ribs lower-L Views
Synonyms
XR Ribs lower-L Views
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
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 is a byproduct of muscle breakdown and is normally filtered out by your kidneys. High levels can indicate reduced kidney function, while low levels may suggest overhydration or other conditions. This test is often used alongside other measures, like blood urea nitrogen (BUN), to evaluate kidney health.

How the Test Works

Blood is drawn from a vein, usually in your arm. The sample is sent to a lab where creatinine is measured using a standard chemical method to detect its concentration in your serum or plasma.

Preparation and Timing

No special preparation is needed for this test. You may eat and drink normally, but avoid excessive alcohol or large amounts of protein-rich foods 24 hours before testing, as they can temporarily affect creatinine levels.

What to Expect After the Test

After the blood draw, you may feel a brief pinch or discomfort. The site will be covered with a bandage. Results are typically available within a few days, depending on lab processing times.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

What Does a High Creatinine Level Mean?
High creatinine levels may signal impaired kidney function, which can be caused by conditions like chronic kidney disease, dehydration, or blockages in the urinary tract. Your doctor will consider other factors, such as your overall health and symptoms, to interpret results accurately.
What Does a Low Creatinine Level Mean?
Low creatinine levels might indicate overhydration, muscle wasting, or certain liver or heart conditions. However, low levels alone are less commonly concerning unless combined with other symptoms or test results.
How Often Should I Get This Test?
Your doctor may recommend this test periodically if you have a history of kidney problems, diabetes, high blood pressure, or other conditions that affect kidney function. Regular monitoring helps track changes over time.
  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