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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 breakdown, in your blood or plasma. It helps assess kidney function.

Quick summary

["A creatinine test helps doctors check how well your kidneys are filtering waste from your blood."]

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

Key facts at a glance

LOINC
18552-0
Short code
J Pnt ST Amp+20ms L-V3
Synonyms
J Pnt ST Amp+20ms L-V3
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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 metabolism and is filtered out by your kidneys. High levels can indicate reduced kidney function, while low levels may suggest dehydration or other conditions. This test is often used alongside other kidney function tests to monitor overall kidney health.

How the Test Works

Blood is drawn from a vein, typically in your arm. The sample is sent to a lab where creatinine levels are measured using a standard chemical method that detects waste products in your blood or plasma.

What to Expect Before the Test

You may be asked to fast for a few hours before the test, though this is not always required. Avoid strenuous exercise or heavy meals 24 hours prior. Stay hydrated unless instructed otherwise by your healthcare provider.

What to Expect During the Test

The test involves a simple blood draw. You may feel a slight pinch or discomfort, but it usually takes only a few minutes. You can resume normal activities immediately afterward.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

How often should I get this test?
The frequency depends on your health condition. Healthy adults may not need routine testing unless recommended by a doctor. People with kidney disease, diabetes, or high blood pressure often get this test more frequently, such as every 3–6 months.
What does a high or low creatinine level mean?
High levels can indicate poor kidney function, but they can also be influenced by factors like dehydration, muscle mass, or certain medications. Low levels might suggest dehydration or conditions that reduce muscle mass. Your doctor will interpret results in the context of your overall health.
Can diet affect creatinine levels?
Dietary changes like eating more protein can temporarily raise creatinine levels, but this effect is usually short-term. Long-term kidney health is more influenced by overall health management, hydration, and medical treatments rather than diet alone.
  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