Skip to content

C-reactive protein (CRP) by nephelometry

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 doctors assess inflammation in your body.

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

Key facts at a glance

LOINC
111574-0
Short code
M catarhls DNA BAS NAA+n-prb-NCncRng
Synonyms
M catarhls DNA BAS NAA+n-prb-NCncRng
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
non-probe-amp-tar
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, monitor conditions like arthritis, infections, or heart disease, or evaluate responses to treatments. It can also help identify early signs of certain infections or autoimmune disorders.

What Does a High or Low Level Mean?

Elevated CRP levels often indicate inflammation, infection, or other health issues. Very low levels may suggest no active inflammation, but they can also be influenced by factors like age, genetics, or certain medications. Your results will be interpreted by your healthcare provider based on your overall health and symptoms.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then analyzed in a lab using nephelometry, a method that measures how much light is scattered by the CRP protein in your sample.

What Can Affect My Results?

Several factors can influence CRP levels, including recent infections, injuries, stress, certain medications (like steroids), smoking, or underlying health conditions. It’s important to discuss your medical history and any recent activities with your healthcare provider to ensure accurate results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Nephelometry)

Frequently asked questions

How often will I need this test?
The frequency depends on your medical condition and treatment plan. Some people need CRP tests regularly to monitor their health, while others may only need it once or occasionally. Follow your healthcare provider’s instructions for scheduling.
Can I eat or drink anything before the test?
You can typically eat and drink normally before this test, as it doesn’t require fasting. However, always check with your healthcare provider for any specific instructions related to your test.
What are the possible side effects of having blood drawn?
Most people experience only minor discomfort or bruising at the injection site. Rarely, some may feel lightheaded or experience a small amount of pain. If you experience excessive bleeding, swelling, or signs of infection, contact your healthcare provider.
  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