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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 in your blood, a marker often used to check for inflammation or infection.

Quick summary

["CRP helps track inflammation, which may signal infections, autoimmune conditions, or other health concerns."]

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

Key facts at a glance

LOINC
110732-5
Short code
M myc my sc Ab Msmt Ser
Synonyms
M myc my sc Ab 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
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 CRP Matters in Your Health

CRP is produced by your liver in response to inflammation. Elevated levels can indicate conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis), or other inflammatory processes. It’s also sometimes used to monitor treatment responses or assess risk for certain heart conditions.

How the Test Works

Your blood sample is analyzed using nephelometry, a method that measures how much light scatters when CRP particles interact with antibodies. This helps determine your CRP level in the bloodstream.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic or liver evaluation. Avoid strenuous activity or certain medications (like NSAIDs) that could affect inflammation levels.

Common Causes of Elevated CRP

High CRP levels may be due to infections (bacterial or viral), injuries, surgeries, or conditions like lupus, arthritis, or heart disease. Chronic inflammation from conditions like obesity or metabolic syndrome can also raise CRP.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

What does a high CRP mean?
A high CRP suggests inflammation is present. While it doesn’t specify the cause, it can guide doctors to investigate infections, autoimmune diseases, or other inflammatory processes. Low or normal CRP levels typically mean less inflammation, but further evaluation may still be needed if symptoms persist.
How often should I get this test?
Your doctor will determine the frequency based on your symptoms, medical history, and other tests. Some patients get CRP checks annually or more often if they have chronic conditions like heart disease or arthritis.
Can diet or lifestyle affect CRP levels?
Yes! Reducing inflammation through diet (e.g., Mediterranean diet), exercise, and avoiding smoking can lower CRP levels. Stress management and weight control may also help.
  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