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C-reactive protein (CRP) by nephelometry (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 inflammation, often used to monitor conditions like infections or autoimmune diseases."]

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

Key facts at a glance

LOINC
44180-8
Short code
Deprecated Sinuses XR V2 Ltd
Synonyms
Deprecated Sinuses XR V2 Ltd
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?

Your healthcare provider may order a CRP test to check for signs of inflammation, monitor chronic conditions, or evaluate symptoms like fever, joint pain, or swelling. It can also help determine if an infection is present or if your body is overreacting to certain conditions.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, similar to other blood tests. If you’re on blood thinners, let your provider know before the test.

What Happens During the Test?

The test involves drawing a small amount of blood from your arm. The sample is then analyzed in a lab using nephelometry, a method that measures how much light is scattered by particles in the blood, indicating CRP levels.

What Are the Results?

Results are typically reported in milligrams per liter (mg/L). Higher than normal levels may suggest inflammation, infection, or other health issues. Your provider will interpret the results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated CRP levels often indicate acute inflammation, such as infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis), or other inflammatory conditions. It can also be used to monitor treatment responses or track chronic inflammation over time. However, CRP alone doesn’t diagnose a specific condition—it’s used alongside other tests and clinical findings.

Short name

CRP (Nephelometry)

Frequently asked questions

How long does it take to get my CRP test results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will contact you once they have the results.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors like diet, exercise, and stress can influence CRP levels. Eating a heart-healthy diet, staying active, and managing stress may help lower CRP in some people. However, CRP is primarily a marker of inflammation, not a direct measure of diet or exercise alone.
Is CRP the same as a white blood cell count (WBC) test?
No, CRP and WBC are different. CRP measures a protein produced by the liver in response to inflammation, while WBC counts the number of white blood cells in your blood. Both tests can help assess health but serve different purposes.
  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