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Plasma Creatinine (Creatinine Level)

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 how well your kidneys are filtering 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
37616-0
Short code
XR Pelvis 1V
Synonyms
XR Pelvis 1V
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 Your Kidneys Matter

Your kidneys filter waste and extra substances from your blood, including creatinine. High levels of creatinine can signal kidney problems, while low levels might indicate dehydration or other conditions. This test is often used alongside other kidney function tests, like blood urea nitrogen (BUN), to get a full picture of kidney health.

What to Expect Before the Test

No special preparation is usually needed for this test. You may be asked to fast for 8–12 hours before the test if it’s part of a larger panel, but creatinine alone often doesn’t require fasting. Drink plenty of water the day before if you’re concerned about dehydration.

Common Causes of Abnormal Results

High creatinine levels may suggest kidney disease, poor kidney function, or conditions that increase muscle breakdown (e.g., severe illness, trauma). Low levels could mean dehydration, low muscle mass, or certain medications. Your doctor will consider your overall health and other test results to interpret results accurately.

When You Might Need This Test

Doctors order creatinine tests to monitor kidney function, diagnose kidney disease, check for dehydration, or evaluate conditions like heart failure, diabetes, or muscle disorders. It’s also part of routine check-ups for people at higher risk of kidney problems.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Beyond

Short name

Creatinine

Frequently asked questions

Why do doctors check creatinine levels?
Doctors use creatinine levels to assess kidney function because it’s a reliable marker of how well your kidneys are filtering blood. Over time, consistently high levels may indicate kidney damage that needs treatment or management. It’s also used to guide medications, especially those that affect kidney function.
What if my creatinine level is higher than expected?
A higher creatinine level doesn’t always mean kidney disease right away. Your doctor will look at your overall health, other test results, and symptoms to determine if further action is needed. They may recommend lifestyle changes, medications, or follow-up tests to monitor kidney function.
Can diet affect creatinine levels?
Diet can influence creatinine levels indirectly. High-protein diets may temporarily raise levels, but your kidneys usually adjust over time. Avoiding excessive protein intake isn’t necessary unless your doctor advises it. Staying hydrated is more important for maintaining normal levels.
  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