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Plasma or 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 or plasma. It helps assess how well your kidneys are filtering blood.

Quick summary

["Kidney function is evaluated by checking creatinine levels—higher levels may indicate kidney issues."]

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

Key facts at a glance

LOINC
5975-8
Short code
PAI1 Ag PPP IA-aCnc
Synonyms
PAI1 Ag PPP IA-aCnc
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 Your Kidneys Matter

Kidneys filter waste like creatinine from your blood and keep important substances (like water and electrolytes) balanced. If they don’t work well, waste can build up, leading to health problems. This test helps doctors check if your kidneys are functioning properly.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a fasting panel. Drink plenty of water the day before to help your kidneys work normally. Avoid heavy exercise or NSAIDs (like ibuprofen) 48 hours before testing.

What the Results Mean

Results are compared to a reference range based on age, sex, and health. Higher levels may suggest kidney problems, while lower levels could indicate dehydration or muscle loss. Your doctor will discuss your specific results in detail.

Common Causes of Abnormal Results

High creatinine levels may be due to kidney disease, dehydration, or conditions that reduce blood flow to kidneys (e.g., heart failure). Low levels could result from dehydration, low muscle mass, or liver/kidney disease. Other factors like diet (high-protein foods) or medications can also affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
Your doctor will determine how often you need this test based on your health history, symptoms, and kidney function. For example, people with diabetes or high blood pressure may need it more often than others.
Can I eat or drink before this test?
If it’s a fasting test, avoid food for 8–12 hours before. Water is usually okay unless your doctor says otherwise. If it’s a non-fasting test, eat and drink normally.
Does this test hurt?
No, this test is quick and painless. A small needle is used to draw blood from your arm, but most people feel only a brief pinch.
  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