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Serum Creatinine (Creatinine Level)

Published: August 9, 2026Updated: August 17, 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

["Kidney function and waste removal depend on this test."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
38118-6
Short code
XR Neck 2V Lat
Synonyms
XR Neck 2V Lat
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
CPT
82553
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 check for kidney problems, monitor kidney function over time, or evaluate symptoms like fatigue, swelling, or changes in urine output. It’s also used before certain procedures or surgeries to ensure your kidneys are healthy.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel, but this isn’t always required for just the creatinine test alone. Drink plenty of water the day before if you’re dehydrated.

How the Test Is Done

A healthcare provider will draw blood from a vein, usually in your arm. The process takes a few minutes, and you may feel a brief pinch. The sample is sent to a lab for analysis.

What the Results Mean

Higher than expected levels may indicate kidney problems or conditions that affect kidney function, such as diabetes or heart disease. Lower levels could suggest dehydration or muscle breakdown. Your doctor will interpret results in the context of your overall health.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

How often should I get this test?
The frequency depends on your health. People with kidney disease may need this test monthly or more often, while healthy individuals might get it once a year or less. Your doctor will determine the best schedule for you.
What can affect my creatinine levels?
Several factors can influence creatinine levels, including muscle mass (higher muscle = higher levels), dehydration, diet (especially protein intake), certain medications, and kidney disease. If you’ve had recent surgery, illness, or changes in activity level, let your doctor know.
Can I prepare for this test at home?
While no strict home preparation is needed, avoid excessive protein intake 24 hours before the test if your doctor advises it. Drink water as usual unless instructed otherwise, as dehydration can affect 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 17, 2026. · Read our editorial policy