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Serum Creatinine (Qualitative or Quantitative Measurement)

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

This test measures the level of creatinine, a waste product from muscle metabolism that your kidneys filter out of your blood.

Quick summary

["Your kidneys’ ability to filter waste may be assessed with this simple blood test."]

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

Key facts at a glance

LOINC
31921-0
Short code
N men sg Y Ag Spec Ql
Synonyms
N men sg Y Ag Spec Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 remove from your bloodstream. High levels can indicate impaired kidney function, though other factors like muscle mass or diet may also influence results.

Why Might This Test Be Ordered?

Doctors may order this test to check kidney health, 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 small blood sample is drawn from your arm, and the lab analyzes it for creatinine levels using an automated method that detects waste products in your serum.

What Are Common Results?

Results are typically reported as a concentration (e.g., milligrams per deciliter). While reference ranges vary by lab, higher-than-expected levels may signal kidney strain, while lower levels may warrant further investigation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Beyond

Short name

Serum Creatinine

Frequently asked questions

What does a high creatinine level mean?
A high creatinine level often suggests your kidneys are not filtering blood as well as they should, which can indicate kidney disease or damage. However, other conditions—like dehydration, muscle disorders, or certain medications—may also affect results.
How often should I get this test?
Your doctor will determine how often you need this test based on your health history, symptoms, and any ongoing conditions. Regular monitoring may be recommended for people with diabetes, heart disease, or a history of kidney problems.
Can diet or exercise affect my creatinine levels?
Yes, diet (especially protein intake) and muscle mass can influence creatinine levels. High-protein diets or muscle loss may raise levels, while dehydration can temporarily spike them. Always discuss dietary changes with your healthcare provider before testing.
  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