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Serum Creatinine (Mass Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood serum.

Quick summary

["Helps assess kidney function by tracking how well your kidneys filter waste."]

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

Key facts at a glance

LOINC
90282-5
Short code
Gram Stn Cath Tip
Synonyms
Gram Stn Cath Tip
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
gram-stain
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 that your kidneys normally filter out of your blood. High levels can indicate kidney problems, while low levels may suggest dehydration or muscle loss.

Why Is This Test Done?

Doctors order creatinine tests to check kidney function, monitor chronic conditions like diabetes or heart disease, or evaluate symptoms such as swelling, fatigue, or changes in urine output.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis using an automated method to measure creatinine concentration.

What Do Results Mean?

Results are compared to a reference range, but exact values can vary by lab. High creatinine levels may signal impaired kidney function, while very low levels could indicate dehydration or other health issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Health

Short name

Creatinine

Frequently asked questions

How often will I need this test?
Your doctor may recommend this test periodically if you have kidney-related conditions, chronic illnesses, or risk factors like high blood pressure or diabetes. Follow-up tests are often scheduled based on your overall health and symptoms.
What does a high creatinine level mean?
A high creatinine level suggests your kidneys may not be filtering waste as efficiently as they should. This could be due to kidney disease, dehydration, or other health conditions. Your doctor will discuss further steps based on your results and medical history.
Can I eat or drink before this test?
For most creatinine tests, you may eat and drink normally unless instructed otherwise. However, if your doctor has specific guidelines (e.g., fasting), follow them to ensure accurate 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 16, 2026. · Read our editorial policy