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C-reactive protein (CRP) by nephelometry (plasma)

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 doctors track inflammation, infection, or other health conditions."]

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

Key facts at a glance

LOINC
94555-0
Short code
dRVVT/dRVVT cfm p DOAC neut PPP-Rto
Synonyms
dRVVT/dRVVT cfm p DOAC neut PPP-Rto
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
Units
N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
Method
coag
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 CRP testing to monitor conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis), or to check for signs of inflammation after surgery or injury. It can also help assess heart disease risk or evaluate responses to treatments.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein in your arm to draw blood. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Higher CRP levels often indicate inflammation or infection, while lower levels may suggest reduced inflammation. Your results will be compared to standard reference ranges for your age and health status.

Common Conditions Monitored

CRP is used to diagnose or monitor conditions like infections, autoimmune diseases, heart disease, and post-surgical inflammation. It’s not a diagnostic test for itself but a marker to guide treatment decisions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a sensitive marker of systemic inflammation. Elevated levels can signal underlying conditions requiring further evaluation, such as infections, chronic diseases, or inflammatory responses. Always discuss results with your healthcare provider for personalized interpretation.

Short name

CRP (Plasma)

Frequently asked questions

What causes CRP levels to be high?
High CRP levels can be caused by infections (like colds or flu), injuries, autoimmune diseases (like lupus or rheumatoid arthritis), heart disease, or other inflammatory conditions. Stress, smoking, or certain medications may also affect CRP levels.
Is CRP testing painful?
The blood draw for CRP testing is generally mild discomfort, similar to a standard blood test. Most people feel only a slight pinch or pressure. If you’re anxious about needles, let your provider know they may offer options like a tourniquet or distraction techniques.
How often should I get CRP tested?
The frequency of CRP testing depends on your health condition and treatment plan. Your healthcare provider will determine how often to check it, whether it’s for routine monitoring, follow-up, or specific situations like post-surgery recovery or managing chronic diseases.
  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