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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 plasma. It helps assess kidney function.

Quick summary

["A creatinine test helps doctors check how well your kidneys are filtering waste from your blood."]

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

Key facts at a glance

LOINC
49949-1
Short code
GH 12:30 PM SerPl-aCnc
Synonyms
GH 12:30 PM 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 This Test Matters

Creatinine is a byproduct of muscle breakdown and is normally filtered out by your kidneys. High levels may indicate kidney problems, while low levels could suggest dehydration or muscle disorders. This test is often used alongside other measures like blood urea nitrogen (BUN) to evaluate kidney health.

How the Test Works

A small blood sample is taken from your arm and sent to a lab. The lab uses a specialized method (likely enzymatic or nephelometric) to measure the creatinine concentration in your plasma. Results are compared to a general reference range to identify any potential issues.

What to Expect Before the Test

No special preparation is needed for this test. You may have a slight bruise or soreness at the injection site, but it usually resolves quickly. Avoid strenuous activity or eating heavy meals before the blood draw to ensure accurate results.

Common Results and Next Steps

Results may be reported as a single number representing the creatinine concentration. If your levels are outside the expected range, your healthcare provider may recommend further testing or adjustments to your treatment plan, such as monitoring hydration or adjusting medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

What does a high creatinine level mean?
High creatinine levels can signal impaired kidney function, as your kidneys may not be filtering waste efficiently. This could be due to chronic kidney disease, dehydration, or other conditions affecting kidney health. Your doctor may also check for other signs of kidney problems, such as protein in urine or changes in blood pressure.
What does a low creatinine level mean?
Low creatinine levels might suggest dehydration, low muscle mass, or certain medical conditions that reduce muscle metabolism. In some cases, it could also indicate overhydration or errors in test interpretation. Your doctor will consider other factors, like your medical history and symptoms, to determine the cause.
Does diet affect this test?
Dietary factors like protein intake can influence creatinine levels, but the test itself measures the waste product from muscle breakdown, which is influenced more by muscle mass and kidney function than diet alone. Avoiding excessive protein before the test may help ensure consistency, but this is not always necessary.
  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