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C-reactive protein (CRP) by mass concentration (serum/plasma)

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

This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation in your body.

Quick summary

["CRP helps identify and monitor inflammation, often used to check for infections, autoimmune conditions, or other health issues."]

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

Key facts at a glance

LOINC
27376-3
Short code
Deprecated C peptide SerPl-mCnc
Synonyms
Deprecated C peptide SerPl-mCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85610
SNOMED
396252006
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 healthcare provider may order this test to check for signs of inflammation, monitor chronic conditions like heart disease or arthritis, or evaluate symptoms such as fever, pain, or swelling that may suggest an infection or other health problem.

Common Uses and Conditions

Common reasons include assessing infection risk (e.g., after surgery or trauma), monitoring autoimmune diseases (e.g., rheumatoid arthritis), or evaluating symptoms like joint pain, fever, or heart-related concerns.

Sample Collection and Preparation

A blood sample is drawn from a vein in your arm. The blood is then processed to separate serum or plasma, which is sent to the lab for testing. This test does not require fasting.

What to Expect Before the Test

No special preparation is needed, but inform your provider about any medications you’re taking, especially blood thinners, as they may affect results.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

What does a high CRP level mean?
A high CRP level often signals inflammation or infection, but it can also occur with other conditions like heart disease, arthritis, or certain cancers. Your provider will review your symptoms and other test results to determine the cause.
How often should I get this test?
Frequency depends on your health condition. Some people get CRP tests every few months (e.g., for heart disease monitoring), while others may need it only occasionally (e.g., after an injury or illness). Follow your provider’s recommendations.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors like diet (e.g., Mediterranean diet), exercise, and weight management can influence CRP levels. Reducing inflammation may lower CRP, but results vary by individual.
  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