Skip to content

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. It helps assess kidney function.

Quick summary

["A key indicator of how well your kidneys filter waste from your blood."]

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

Key facts at a glance

LOINC
21464-3
Short code
uPA Tiss Ql
Synonyms
uPA Tiss Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 help doctors check if your kidneys are working properly. High levels may suggest kidney problems, while low levels could indicate dehydration or other conditions. This test is often used alongside other kidney function tests.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel. Drink plenty of water the day before to ensure accurate results.

Common Causes of Abnormal Results

Elevated creatinine levels might indicate reduced kidney function, dehydration, or muscle breakdown. Low levels could suggest dehydration, overhydration, or certain medical conditions. Always discuss results with your healthcare provider.

How This Test Is Performed

A small blood sample is drawn from a vein in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine concentration using a specialized test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Beyond

Short name

Creatinine Level

Frequently asked questions

What does a high creatinine level mean?
A high creatinine level may signal impaired kidney function, though it can also be influenced by factors like muscle mass, hydration status, or certain medications. Your doctor will consider your overall health and other test results to interpret the result.
Can diet affect creatinine levels?
Dietary changes alone won’t drastically alter creatinine levels, but eating a high-protein diet or consuming large amounts of fluids can temporarily impact results. Always follow your healthcare provider’s guidance for test timing and preparation.
How often should I get this test?
Frequency depends on your health status. People with kidney disease may need this test more often, while others with no known kidney issues may only need it periodically, as recommended by their doctor.
  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