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Serum or Plasma Creatinine Concentration (Mass Concentration)

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

This test measures the level 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 evaluating 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
19225-2
Short code
DO-Hgb MFr BldA
Synonyms
DO-Hgb MFr BldA
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
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

Kidneys filter waste and excess substances from your blood, including creatinine. When kidneys don’t work properly, creatinine levels can rise, signaling potential kidney damage or disease.

What to Expect During the Test

You’ll provide a blood sample, usually from a vein in your arm. No special preparation is needed, but fasting may be required depending on your lab’s protocol.

How Results Are Used

Doctors use creatinine levels to calculate your **estimated glomerular filtration rate (eGFR)**, a measure of kidney function. Low levels may indicate overhydration or muscle disorders, while high levels suggest kidney issues.

Common Reasons for Testing

Your doctor may order this test if you have symptoms like swelling, fatigue, or frequent urination; if you have a history of kidney problems; or as part of routine health checks.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

How often should I get this test?
Your doctor will determine how often you need this test based on your health status. For example, people with diabetes or high blood pressure may need it more frequently than others.
What does a low creatinine level mean?
A low creatinine level might suggest you’re dehydrated or have very little muscle mass. It could also indicate conditions like liver disease or certain metabolic disorders.
Can diet affect my creatinine test results?
Yes, eating a high-protein diet or consuming large amounts of meat can temporarily raise creatinine levels. Your doctor may ask you to avoid excessive protein for a day or two before testing.
  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