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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

Your kidneys filter waste from blood; this test checks kidney function.

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

Key facts at a glance

LOINC
28531-2
Short code
MYHOMETOWNMEANSALOT
Synonyms
—
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
reported-living-hiv
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 Does Creatinine Measure?

Creatinine is a byproduct of muscle breakdown and is naturally excreted by the kidneys. Elevated levels may indicate impaired kidney function, while lower levels could suggest muscle underuse or overhydration. This test is often used alongside other kidney function tests to diagnose or monitor kidney disease.

Why Is This Test Done?

Doctors order creatinine tests to evaluate kidney health, especially in people with symptoms like fatigue, swelling, or frequent urination. It’s also used before surgeries, during pregnancy, or when managing conditions like diabetes or heart disease.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a different method. Drink plenty of water the day before to ensure normal urine flow.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. The process is quick and usually painless. You may feel a slight pinch, but it won’t take long.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels can reflect kidney function, but they’re not the only indicator. High levels may signal kidney damage, while very low levels could suggest dehydration, muscle loss, or errors in test interpretation. Regular monitoring helps track kidney health over time, especially in people with chronic conditions.

Short name

Creatinine

Frequently asked questions

Why might my creatinine level be higher than expected?
Possible causes include kidney disease, dehydration, high muscle mass, or certain medications. If you’ve had recent surgery, trauma, or a high-protein diet, those factors could also affect results.
Could my results be affected by what I ate or drank before the test?
Fasting for 8–12 hours before the draw is standard, but hydration status can influence results. If you’re unsure about lab instructions, ask your provider to confirm.
Do I need to do anything special if I have kidney disease?
If you have known kidney issues, your doctor may monitor creatinine levels closely. Follow their advice on diet, hydration, and medications to help manage your condition.
  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