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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 breakdown, 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 how well your kidneys remove waste from your blood."]

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

Key facts at a glance

LOINC
37636-8
Short code
XR Abd Views
Synonyms
XR Abd Views
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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 can indicate how efficiently your kidneys are working. High levels may suggest kidney problems, while low levels could indicate dehydration or muscle loss. This test is often used alongside other measures, like blood urea nitrogen (BUN), to evaluate kidney health.

What to Expect Before the Test

You may be asked to fast for a few hours before the test, but this depends on your doctor’s instructions. Avoid strenuous activity or certain medications that could affect results. If you’re on dialysis, your doctor will guide you on timing.

How the Test Works

A small blood sample is drawn from a vein in your arm. The sample is sent to a lab, where it’s analyzed to measure creatinine levels using a specialized method, such as enzymatic or spectrophotometric techniques.

Possible Results and Next Steps

Your results will be compared to a reference range provided by your healthcare provider. Abnormally high levels may prompt further testing, such as additional kidney function tests or imaging, to explore underlying causes like kidney disease or dehydration.

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 often signal impaired kidney function, as your kidneys may struggle to remove waste products efficiently. This could indicate chronic kidney disease, acute kidney injury, or conditions like heart failure or severe dehydration.
What does a low creatinine level mean?
Low creatinine levels may suggest dehydration, muscle wasting, or liver disease, which can reduce muscle mass or affect metabolism. However, some medications or genetic factors can also influence results, so results should always be interpreted with clinical context.
Can diet affect creatinine levels?
Yes, diet can influence creatinine levels indirectly. High-protein diets may temporarily increase muscle breakdown, raising creatinine temporarily. However, kidney function itself is the primary focus of this test, so diet changes alone won’t alter the test’s clinical meaning unless related to muscle mass or hydration.
  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