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Serum or Plasma Creatinine Concentration (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

["A creatinine test helps check kidney function by measuring how well your kidneys remove waste from your blood."]

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

Key facts at a glance

LOINC
9910-1
Short code
P wave dur L-V4
Synonyms
P wave dur L-V4
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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 and extra fluids from your blood, keeping your body balanced. Creatinine is a natural waste product that builds up when your kidneys aren’t working properly. High levels can signal kidney problems, even before other symptoms appear.

What the Test Shows

This test specifically looks at creatinine levels in your blood or plasma. Creatinine levels can rise if your kidneys aren’t filtering waste efficiently, which may indicate kidney disease or damage.

How It’s Done

A small blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine concentration.

What to Expect Before the Test

You may need to fast for 8–12 hours before the test, but this depends on your doctor’s instructions. Avoid strenuous activity or certain medications that could affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

High creatinine levels often mean your kidneys aren’t working as well as they should, which can lead to long-term health risks like heart disease, bone problems, or fluid buildup. Low levels may suggest dehydration or overhydration.
Your creatinine test results help doctors track kidney function over time, especially if you have diabetes, high blood pressure, or a family history of kidney disease.
What causes creatinine levels to change?
Several factors can affect creatinine levels, including muscle mass (higher muscle = higher creatinine), dehydration, or certain medications. Kidney disease, heart problems, or severe infections can also raise levels.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition. Regular monitoring may be recommended if you have chronic kidney disease, diabetes, or other risk factors.
  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