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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

["A creatinine test checks kidney function by measuring waste product levels in your blood."]

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

Key facts at a glance

LOINC
43541-2
Short code
Deprecated Finger.2nd-L XR GE 3V
Synonyms
Deprecated Finger.2nd-L XR GE 3V
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 This Test Matters

Your kidneys normally filter waste products like creatinine from your blood. High levels can signal kidney problems, while low levels might indicate dehydration or muscle issues. This test is often used alongside other kidney function tests to diagnose or monitor conditions like chronic kidney disease.

What to Expect Before the Test

No special preparation is needed unless instructed by your healthcare provider. You may be asked to fast for 8–12 hours before the test if it’s part of a larger panel, but this is uncommon for a standalone creatinine test. Drink plenty of water the day before to ensure accurate results.

What Happens During the Test

A blood sample will be drawn from a vein in your arm by a healthcare professional. The process is quick and typically painless. You may feel a slight pinch or sting, but it usually doesn’t cause significant discomfort.

Possible Results and Next Steps

Results are compared to a reference range, but individual ranges can vary. High creatinine levels may prompt further kidney function tests or evaluations for conditions like diabetes or heart disease. Low levels might require additional checks for hydration status or muscle disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine

Frequently asked questions

What causes high creatinine levels?
High creatinine levels often indicate reduced kidney function, but they can also result from dehydration, muscle breakdown (e.g., from injury or illness), or certain medications. Chronic kidney disease, diabetes, or heart conditions may also contribute.
What causes low creatinine levels?
Low creatinine levels can occur if you’re dehydrated, have very little muscle mass, or are taking certain medications that affect muscle metabolism. Rarely, it may signal an underlying metabolic disorder.
How often should I get this test?
Your doctor will determine how often to check your creatinine levels based on your health status. Regular monitoring is common for people with kidney disease, diabetes, or heart conditions, but it’s not routine for healthy individuals unless advised otherwise.
  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