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C-reactive protein (CRP) in serum

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

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

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
44979-3
Short code
C pneum Ab sp2 Ser Ql
Synonyms
C pneum Ab sp2 Ser Ql
Category
chemistry
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

What Is C-Reactive Protein?

C-reactive protein (CRP) is a marker that your immune system releases when it detects inflammation. It’s often used to check for conditions like infections, injuries, or autoimmune diseases. While CRP itself isn’t the cause of inflammation, it’s a key indicator that your body is responding to it.

Why Might You Need This Test?

Doctors may order CRP tests to monitor chronic conditions (like arthritis or heart disease), assess symptoms of infection, or evaluate the effectiveness of treatments. It can also help guide decisions about procedures or surgeries by measuring baseline inflammation levels.

How Is the Test Done?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum (the liquid part after clotting), which is sent to a lab for analysis. Results are typically ready within a few days.

What Do Results Mean?

Results are compared to general reference ranges, but they can vary by lab. High CRP levels may signal inflammation, infection, or other health concerns, while low levels might suggest minimal or controlled inflammation. Your doctor will interpret results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP Serum

Frequently asked questions

How often do I need this test?
CRP tests are often used as a screening or monitoring tool, especially for conditions like cardiovascular disease, rheumatoid arthritis, or sepsis. Frequency depends on your medical needs—your doctor will determine how often you should be tested.
Can I influence my CRP levels?
Yes! Lifestyle factors like diet (e.g., reducing processed foods, increasing fruits/vegetables), exercise, managing stress, and quitting smoking can help lower inflammation. Medications like anti-inflammatory drugs may also be prescribed if needed.
What if my CRP is elevated?
An elevated CRP may prompt further testing (e.g., blood cultures, imaging) or adjustments to treatment. Your doctor will discuss next steps based on your symptoms and lab results, possibly including lifestyle changes or additional tests to identify the cause.
  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