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Serum or Plasma Creatinine Concentration (Standard Method)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood or urine. It helps assess how well your kidneys are filtering blood.

Quick summary

["A creatinine test helps check kidney function by measuring waste products in your blood or urine."]

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

Key facts at a glance

LOINC
9948-1
Short code
Q wave dur L-V6
Synonyms
Q wave dur L-V6
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 can indicate how well your kidneys are working. High levels may suggest kidney problems, while low levels could be due to muscle mass changes or other conditions. This test is often used alongside other kidney function tests to diagnose or monitor kidney disease.

What to Expect Before the Test

No special preparation is usually needed for a blood creatinine test. For a urine test, you may be asked to collect a sample over a 24-hour period or provide a random sample. Avoid excessive protein intake or strenuous exercise before a urine test if instructed.

Common Causes of Abnormal Results

High creatinine levels may be caused by reduced kidney function, dehydration, severe muscle damage, or conditions like heart failure or diabetes. Low levels might be linked to low muscle mass, overhydration, or certain liver or heart conditions.

How Results Are Interpreted

Your healthcare provider will compare your results with your baseline or reference ranges to determine if your levels are within normal limits. They’ll consider your overall health and other test results to make a diagnosis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

What does my creatinine level tell me about my kidney health?
A creatinine level alone doesn’t diagnose kidney disease, but it’s a key part of the picture. Your doctor will use it alongside other factors like blood pressure, urine tests, and symptoms to assess kidney function. Chronic kidney disease (CKD) is often detected early with consistent monitoring of creatinine and other kidney markers.
Can diet affect my creatinine test results?
Yes, diet can influence creatinine levels. High-protein foods or intense exercise may temporarily raise creatinine in the blood. For a 24-hour urine test, following your doctor’s instructions about diet and fluid intake is important to get accurate results.
What if my creatinine level is higher than usual?
If your creatinine level is elevated, your doctor may recommend further testing or monitoring to check for kidney issues. They could also adjust medications or treatments to support kidney health, depending on the cause and severity of your 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