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Serum Creatinine (Creatinine Level)

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

["Kidney function check via creatinine levels."]

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

Key facts at a glance

LOINC
59390-5
Short code
Hu Ab Titr Ser IF
Synonyms
Hu Ab Titr Ser IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 is a byproduct of muscle breakdown and is normally filtered out of your blood by your kidneys. High levels can indicate kidney problems, while low levels may suggest dehydration or muscle disorders. This test is often used alongside other measures like blood urea nitrogen (BUN) to evaluate kidney function.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into your arm to draw blood. If you’re on a low-protein diet or have recently exercised, your doctor may advise adjusting your timing to get more accurate results.

Common Causes of Abnormal Results

Elevated creatinine levels may signal kidney disease, dehydration, or conditions like heart failure or severe muscle damage. Lower-than-normal levels might suggest dehydration, overhydration, or certain muscle disorders. Always discuss symptoms with your healthcare provider.

How Results Are Interpreted

Results are compared to a reference range specific to your age, sex, and overall health. Your doctor will consider your medical history and other test results to determine if your levels are within a healthy range.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Beyond

Short name

Creatinine

Frequently asked questions

What might cause my creatinine level to be high?
High creatinine levels can be caused by reduced kidney function, dehydration, severe muscle injury, or conditions like diabetes or heart disease. If you notice symptoms like swelling, fatigue, or changes in urine output, talk to your doctor about further evaluation.
Could my diet affect this test?
Yes, eating a high-protein diet or consuming certain supplements (like creatine) shortly before the test can temporarily raise creatinine levels. Your doctor may recommend timing your meal or fasting to get the most accurate reading.
Why do some people’s reference ranges differ?
Reference ranges can vary by lab, age, sex, and individual health. For example, older adults or those with muscle mass differences may have slightly different ranges. Your doctor will use your specific results in the context of your overall health.
  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