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Creatinine in Serum or Plasma (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. Creatinine levels help assess how well your kidneys are filtering blood.

Quick summary

["Kidney function check via blood waste product."]

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

Key facts at a glance

LOINC
53055-0
Short code
Creatine Amn-sCnc
Synonyms
Creatine Amn-sCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why Creatinine Levels Matter

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 wasting. This test is often used alongside other measures to evaluate kidney health.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into a vein (usually in your arm) to draw blood. If you’re concerned about needles, let your healthcare provider know. Avoid strenuous activity or eating/drinking for 8–12 hours before testing if instructed.

Common Causes of Abnormal Results

Elevated creatinine levels may be due to kidney disease, dehydration, or conditions that reduce blood flow to the kidneys. Low levels might result from dehydration, severe muscle loss, or overhydration. Your doctor will consider other factors, like diet, activity level, and overall health.

When This Test Might Be Ordered

Your doctor may order this test to check for kidney problems, monitor chronic conditions (like diabetes or heart disease), or evaluate symptoms such as swelling, fatigue, or changes in urine output.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum/Creatinine

Frequently asked questions

How often should I get this test?
Your doctor will determine how often you need this test based on your health status, medical history, and any ongoing conditions. Regular monitoring may be recommended if you have kidney disease, diabetes, or other risk factors.
What do my results mean?
Results are interpreted by your doctor in the context of your overall health. They’ll compare your levels to what’s typical for your age, sex, and health status. Abnormal results may trigger further tests or adjustments to your treatment plan.
Can diet or exercise affect creatinine levels?
Yes, diet (especially protein intake) and exercise can influence creatinine levels. High-protein diets may temporarily raise levels, while dehydration can also increase them. Your doctor may ask about your diet and activity level when reviewing 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