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Plasma or Serum 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

["Kidney function depends on this test to check how well your kidneys remove waste."]

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

Key facts at a glance

LOINC
45141-9
Short code
PA Ab Bld Ql FC
Synonyms
PA Ab Bld Ql FC
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
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 Your Kidneys Matter

Your kidneys are vital for filtering waste and excess substances from your blood, including creatinine. This test helps doctors determine if your kidneys are working properly by measuring how efficiently they remove creatinine from your bloodstream.

What to Expect During the Test

A small blood sample is drawn from your arm. No special preparation is needed, but fasting may be required depending on your doctor’s instructions.

Factors That Can Affect Results

Several factors may influence your creatinine levels, such as muscle mass, hydration status, diet, and certain medications. For example, eating large amounts of protein or being dehydrated can temporarily raise levels.

Common Reasons for Testing

Doctors may order this test to check kidney function before surgeries, diagnose kidney disease, monitor chronic conditions like diabetes or heart disease, or evaluate symptoms like swelling, fatigue, or frequent urination.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High creatinine levels may indicate poor kidney function, while low levels could suggest overhydration or muscle loss. Your doctor will interpret results in relation to your overall health and medical history.

Short name

Creatinine Level

Frequently asked questions

What causes creatinine levels to be higher than usual?
Higher creatinine levels may be due to reduced kidney function, dehydration, muscle damage, or certain medications. If you notice unexplained symptoms like swelling or fatigue, discuss these with your doctor.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will contact you with the final report.
Can diet affect creatinine levels?
Yes, diet can influence creatinine levels. High-protein foods or dehydration may temporarily raise them, while proper hydration supports normal kidney function.
  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