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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 your liver in response to inflammation or infection.

Quick summary

["CRP helps track inflammation in your body, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
111308-3
Short code
C pneum IgM Msmt Ser
Synonyms
C pneum IgM Msmt Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 doctor may order a CRP test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate symptoms such as fever, pain, or swelling that may indicate infection or an immune response. It can also be used before or after certain treatments to see if inflammation is improving or worsening.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into a vein in your arm to draw blood. If you’re concerned about needles or have a hard time staying still, let your doctor or lab staff know so they can help make the process more comfortable.

What the Results Mean

Higher than expected CRP levels often suggest inflammation, infection, or other health issues. Lower levels may indicate no active inflammation. Your doctor will interpret your results in the context of your overall health and medical history.

Common Conditions Monitored

CRP is commonly used to monitor conditions like rheumatoid arthritis, lupus, heart disease, or infections such as pneumonia or urinary tract infections. It can also help assess how well you’re responding to treatments for these conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Nephelometry)

Frequently asked questions

What Does CRP Measure?
CRP is a marker for inflammation. While it doesn’t specifically identify the cause of inflammation, it can signal whether your body is reacting to an infection, injury, or an autoimmune process. It’s often used alongside other tests to get a clearer picture of your health status.
How Often Should I Get This Test?
The frequency of CRP testing depends on your medical needs. Your doctor may recommend it periodically if you have a chronic condition like heart disease or arthritis, or if you’re recovering from surgery or an illness. Follow your doctor’s advice for scheduling.
Are There Any Risks or Side Effects?
There are usually no major risks with a blood draw, but you might feel slight discomfort or bruising at the injection site. Rarely, there could be a slight swelling or redness. If you experience excessive bleeding, pain, or signs of infection (like fever or increased redness), contact your doctor right away.
  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