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Serum or Plasma 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

["A key indicator of kidney function and filtering efficiency."]

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

Key facts at a glance

LOINC
9881-4
Short code
J Pnt Depr L-II
Synonyms
J Pnt Depr L-II
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 levels help doctors check if your kidneys are working properly. High levels may suggest kidney problems, while very low levels could indicate conditions like muscle loss or dehydration.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein for a blood draw. If testing urine, you’ll collect a sample over 24 hours.

Common Causes of Abnormal Results

High creatinine levels can result from kidney disease, dehydration, or severe muscle breakdown. Low levels may occur with muscle wasting, liver disease, or overhydration.

How Results Are Interpreted

Results are compared to a baseline or reference range provided by your healthcare team. They don’t have a universal range but are used relative to your health status and kidney function.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Regular creatinine testing is vital for diagnosing and monitoring kidney disease, managing chronic conditions like diabetes or heart failure, and assessing overall kidney health. It’s often paired with other tests like blood urea nitrogen (BUN) for a fuller picture.

Short name

Creatinine Level

Frequently asked questions

What triggers a creatinine test?
A creatinine test may be ordered if you have symptoms like swelling, fatigue, or changes in urine output; if you have a history of kidney disease or diabetes; or if you’re taking medications that can affect kidney function.
How often should I get this test?
Frequency depends on your health. Healthy adults may not need it unless recommended by a doctor. People with kidney issues or risk factors (like high blood pressure or diabetes) may need it more often, such as every 3–6 months.
Can diet affect creatinine levels?
Yes, high-protein diets or muscle-building exercises can temporarily raise creatinine levels. Avoiding excessive protein for a day or two before testing may help stabilize results.
  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