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Serum or Plasma Creatinine Concentration (Substance Concentration)

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 helps check kidney function by tracking waste removal from your blood."]

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

Key facts at a glance

LOINC
21772-9
Short code
Chr 7 Ts Bld/T Ql
Synonyms
Chr 7 Ts Bld/T Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
cytogenetics
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to evaluate kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used to monitor kidney function in people with diabetes, high blood pressure, or other chronic conditions that affect the kidneys.

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 broader panel. Drink plenty of water the day before to ensure accurate results. Avoid strenuous exercise or taking certain medications that could affect kidney function.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis.

What Do the Results Mean?

Higher than expected levels may indicate poor kidney function, while lower levels could suggest dehydration or muscle breakdown. Your results will be compared to your baseline or clinical context to determine significance.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

What causes creatinine levels to be higher than normal?
Higher-than-normal creatinine levels can result from kidney problems, dehydration, severe muscle breakdown (e.g., from injury or illness), or certain medications. If you notice sudden changes, discuss them with your doctor to explore possible causes.
What if my results are within the normal range?
If your creatinine levels are within the expected range, it generally means your kidneys are functioning normally at that time. However, your doctor may still monitor it regularly if you have risk factors for kidney issues or other health conditions.
Do diet or exercise affect creatinine levels?
Dietary changes (like high-protein meals) or intense exercise can temporarily alter creatinine levels, but they usually return to normal after a few days. Your doctor may recommend adjustments if your levels fluctuate significantly.
  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