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Serum or Plasma Creatinine Concentration (Standard Method)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood or urine.

Quick summary

["Creatinine levels help assess kidney function and detect early kidney problems."]

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

Key facts at a glance

LOINC
9939-0
Short code
Q wave dur L-AVR
Synonyms
Q wave dur L-AVR
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 Is This Test Done?

Your doctor may order this test to check how well your kidneys are filtering waste from your blood. It’s often used to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It can also help diagnose conditions like kidney disease or determine how well a kidney transplant is working.

What to Expect Before the Test

For blood tests, you’ll typically have a small needle inserted into your arm. No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a metabolic panel. For urine tests, you’ll collect a sample at home or in a clinic.

What the Results Mean

Higher-than-normal levels may indicate kidney problems, dehydration, or muscle disorders. Lower-than-normal levels could suggest overhydration or liver/kidney issues. Your doctor will interpret results in relation to your overall health and symptoms.

Common Causes of Abnormal Results

Kidney disease, dehydration, muscle breakdown (e.g., from injury or illness), heart failure, or certain medications can affect creatinine levels. Chronic kidney disease is the most common cause of elevated results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

What does a high creatinine level mean?
A high creatinine level often signals that your kidneys aren’t working as well as they should, which could mean early kidney disease or other conditions affecting blood flow to the kidneys. It may also indicate dehydration or muscle problems, but your doctor will consider other factors to diagnose the cause.
Can diet affect creatinine levels?
Dietary changes like eating more protein or consuming large amounts of meat can temporarily raise creatinine levels, but the test itself doesn’t measure protein directly. Your doctor may adjust interpretation if you have a high-protein diet or recent muscle activity.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status. People with kidney disease or risk factors (like diabetes or high blood pressure) may need it more frequently, while others might only need it once or twice a year.
  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