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Serum Creatinine (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 to assess kidney function.

Quick summary

["Your kidneys filter waste from blood; high creatinine may signal kidney problems."]

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

Key facts at a glance

LOINC
44207-9
Short code
Deprecated Knee-Bl XR AP stand
Synonyms
Deprecated Knee-Bl XR AP stand
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

What Is Creatinine?

Creatinine is a byproduct of muscle breakdown and is naturally produced in the body. It’s filtered out of your blood by your kidneys and excreted in urine. This test helps doctors check how well your kidneys are working by measuring how much creatinine is in your blood.

Why Is This Test Done?

Doctors order creatinine tests 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.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine levels.

What Do Results Mean?

Results are compared to a reference range, but exact values can vary by lab. High levels may indicate kidney problems, while low levels could suggest dehydration or muscle loss.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels are critical for diagnosing and managing kidney disease, guiding treatments like fluid restrictions or medications. It’s also used alongside other tests to assess overall kidney function.

Short name

Creatinine

Frequently asked questions

Why might my creatinine level be higher than usual?
Higher levels can occur if your kidneys aren’t filtering waste properly, from conditions like kidney disease, dehydration, or muscle damage. Other factors like high protein intake or certain medications may also affect results.
What should I do if my creatinine is elevated?
If your doctor finds elevated levels, they may recommend lifestyle changes (like staying hydrated), further kidney tests, or treatments tailored to your condition. Follow their advice closely.
Can diet affect creatinine levels?
Yes, eating high-protein foods or drinking less water can temporarily raise creatinine. Your doctor may advise dietary adjustments if kidney function is compromised, but results should be interpreted with lab context.
  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