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Serum Creatinine (Substance Concentration)

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

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

Quick summary

["Creatinine levels help check kidney function and detect early kidney problems."]

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

Key facts at a glance

LOINC
39489-0
Short code
XR Ribs lower post Views
Synonyms
XR Ribs lower post 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 Is This Test Done?

Your doctor may order this test to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used before surgeries, during pregnancy, or if you have conditions like diabetes or high blood pressure that can affect kidneys.

What to Expect Before the Test

You’ll likely have a simple blood draw from a vein in your arm. No special preparation is needed unless your doctor instructs otherwise, such as fasting for glucose-related tests.

What the Results Mean

Higher-than-normal levels may suggest kidney problems, while lower levels could indicate muscle breakdown or liver disease. Your doctor will interpret results in relation to your overall health.

Common Causes of Abnormal Results

Creatinine can rise due to kidney disease, dehydration, or conditions that reduce blood flow to kidneys. It may drop with muscle wasting or liver issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels are a key marker for kidney function, helping doctors diagnose and manage chronic kidney disease, acute kidney injury, or other conditions affecting blood filtration.

Short name

Creatinine

Frequently asked questions

Will I need to prepare for this test?
No special preparation is usually required, but follow your doctor’s instructions if you’re also having other blood tests (e.g., fasting).
How long will I wait for my results?
Results are typically available within 1–3 business days, depending on lab processing times. Your doctor will discuss them with you.
Can diet affect creatinine levels?
Dietary protein intake may slightly influence creatinine levels, but the test primarily reflects kidney function. Avoid extreme protein restriction unless advised by your doctor.
  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