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C-reactive protein (CRP) – Serum Mass Concentration

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

This test measures the level of C-reactive protein in your blood, a marker often used to assess inflammation or infection.

Quick summary

["CRP helps track inflammation, guiding decisions about treatment or further testing."]

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

Key facts at a glance

LOINC
27155-1
Short code
Deprecated S pneum6 Ab sp2 Ser-mCnc
Synonyms
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Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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, infection, or other health conditions like heart disease, autoimmune disorders, or response to treatment. It can also help monitor chronic conditions like rheumatoid arthritis or lupus.

What Does a High CRP Level Mean?

Elevated CRP levels may indicate an infection, injury, or inflammatory process. However, levels alone don’t specify the cause, so your provider will consider other factors, including symptoms and medical history.

What Does a Low CRP Level Mean?

Low CRP levels typically suggest minimal inflammation, but they don’t rule out conditions like mild infections or chronic diseases without further testing.

How Is This Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis. Results are usually available within a few days.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a non-specific marker, meaning it can rise in response to many conditions. It’s often used alongside other tests to provide a clearer picture of your health status.

Short name

CRP Blood Test

Frequently asked questions

What are the normal ranges for CRP?
There is no single ‘normal’ range for CRP because levels can vary widely depending on age, health status, and other factors. Your provider will interpret results in relation to your specific situation.
Can lifestyle changes affect CRP levels?
Yes, factors like diet, exercise, smoking, and stress can influence CRP levels. Maintaining a healthy lifestyle may help reduce inflammation over time.
Is CRP the same as other inflammation markers?
No, CRP is one of many markers. Others, like erythrocyte sedimentation rate (ESR) or fibrinogen, may be used in different contexts to assess inflammation.
  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