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Plasma or Serum Creatinine Concentration (Mass 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

["Kidney function is evaluated by checking creatinine levels."]

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

Key facts at a glance

LOINC
49942-6
Short code
GH 1 AM SerPl-aCnc
Synonyms
GH 1 AM SerPl-aCnc
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 Is This Test Done?

Doctors order creatinine tests to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used before surgeries, during pregnancy, or when managing conditions like high blood pressure or diabetes.

What to Expect Before the Test

You may need to fast for 8–12 hours before the test, but this depends on the lab’s instructions. Bring any medications you’re taking to your appointment. Avoid strenuous activity the day before.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. It usually takes a few minutes, and you may feel a brief pinch. The sample is sent to a lab for analysis.

What Are Normal Results?

Results vary by age, sex, and muscle mass. Your doctor will compare your results to your baseline or lab’s reference ranges to interpret them.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High creatinine levels may indicate kidney problems, while low levels could suggest dehydration or muscle breakdown. Your doctor will discuss results in the context of your overall health.

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
Your doctor will determine how often you need this test based on your health status, medications, or symptoms. Regular monitoring may be needed if you have kidney disease or other conditions affecting kidney function.
Can diet affect creatinine levels?
Dietary protein intake can influence creatinine levels, but the test itself doesn’t measure protein directly. Avoiding excessive protein before testing may help stabilize results, but follow your doctor’s advice.
What if my results are abnormal?
If your results are outside the expected range, your doctor may recommend further tests, like additional bloodwork or imaging, to investigate kidney function more closely. They’ll discuss next steps with you.
  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