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Serum or Plasma Creatinine 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
23466-6
Short code
T equi Ab Ser Ql IF
Synonyms
T equi Ab Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 Is This Test Done?

Your healthcare provider may order a creatinine test to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used before certain procedures, during pregnancy, or to evaluate chronic conditions like diabetes or heart disease.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a larger panel. Avoid using certain supplements or medications that could affect results. Bring a list of all medications to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but the procedure is quick. If you’re nervous, let them know—they can use a tourniquet to help find the vein.

What Are the Results?

Results are typically reported as a concentration value (e.g., milligrams per deciliter or milligrams per liter). Your provider will compare these numbers to your baseline or reference ranges to determine if your kidneys are working as expected.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High creatinine levels may indicate kidney damage or disease, while low levels could suggest dehydration or muscle breakdown. Repeated tests help track kidney function over time, especially in people with chronic conditions. Always discuss results with your provider—they’ll interpret them in the context of your health.

Short name

Creatinine

Frequently asked questions

How often should I get this test?
Your provider will decide how often to check your creatinine levels based on your health needs. For example, people with kidney disease may need tests every few months, while others may only need it once a year or less.
Can diet or exercise affect my creatinine test results?
Dietary changes (like eating more protein) or intense exercise can temporarily raise creatinine levels. Avoid extreme activity or high-protein meals 24 hours before your test to get the most accurate results.
What if my results are outside the normal range?
If your results are abnormal, your provider will investigate further, possibly ordering additional tests or imaging. They’ll work with you to address any underlying causes, such as kidney issues or dehydration, and develop a treatment plan if needed.
  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