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Serum or Plasma Creatinine (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 and waste removal depend on this test."]

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

Key facts at a glance

LOINC
42154-5
Short code
Deprecated Abd XR AP 1V
Synonyms
Deprecated Abd XR AP 1V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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?

Doctors may order this test to check for kidney disease, monitor kidney function in chronic conditions (like diabetes or high blood pressure), or evaluate kidney damage after exposure to certain medications or toxins. It can also be used to assess overall health, especially in people with symptoms like swelling, fatigue, or changes in urine output.

What to Expect Before the Test

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 broader metabolic panel. Hydration can sometimes affect results, so drink water as directed by your healthcare provider. Avoid strenuous activity or certain medications that might influence kidney function.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The process is quick and typically causes only mild discomfort. The blood sample is sent to a lab for analysis.

What Are the Results?

Results are compared to a reference range that varies by lab and age. High levels may indicate kidney problems, while very low levels could suggest muscle disorders or other conditions. Your doctor will interpret the results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. Healthy adults may not need routine testing unless recommended by a doctor. People with kidney disease, diabetes, or high blood pressure typically get this test every few months or annually, as directed by their healthcare provider.
What can affect my creatinine levels?
Several factors can influence creatinine levels, including dehydration, muscle mass, diet (especially protein intake), and certain medications. For example, eating a high-protein diet or taking certain diuretics may temporarily raise levels. Always discuss any changes in diet, medications, or activity with your doctor before testing.
What if my results are outside the normal range?
If your results are abnormal, your doctor will review them with you and may order additional tests or evaluations. This could include further kidney function tests, imaging, or a detailed medical history review to determine the cause and next steps.
  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