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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 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
31634-9
Short code
S chartarum IgA Qn
Synonyms
S chartarum IgA Qn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 of your blood by your kidneys. High levels can indicate poor kidney function, while low levels may suggest overhydration or other conditions. This test is often used alongside other kidney function tests to monitor kidney health.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, or in some cases, a urine sample may be collected if a 24-hour urine creatinine test is ordered. Drinking water before the test can help ensure accurate results.

What the Results Mean

Results are typically reported in units of milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Your healthcare provider will compare your results to standard reference ranges and consider your overall health to interpret the meaning.

Common Causes of Abnormal Results

High creatinine levels may be due to reduced kidney function, dehydration, muscle disorders, or conditions that increase muscle breakdown. Low creatinine levels might indicate overhydration, low muscle mass, or certain liver or heart conditions. Always discuss your results with your doctor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. People with kidney disease may need this test more often to monitor progression. Healthy individuals may get it as part of routine check-ups, typically every 1–3 years, unless advised otherwise.
Can diet affect my creatinine levels?
Dietary protein intake can influence creatinine levels, but the impact is usually small. High-protein diets may temporarily raise creatinine, while very low-protein diets might lower it. Your doctor will consider your overall diet and health when interpreting results.
What if my creatinine level is out of range?
If your results are abnormal, your doctor will investigate further, possibly with additional tests or discussions about lifestyle changes, medications, or treatments to address the underlying cause.
  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