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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 made 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
24315-4
Short code
CMV IgG+IgM Pnl SerPl
Synonyms
CMV IgG+IgM Pnl SerPl
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 CRP testing to check for signs of inflammation, monitor conditions like arthritis, heart disease, or infections, or evaluate responses to treatments. It can also help identify risks for conditions like heart disease or autoimmune disorders.

What Does a High or Low CRP Level Mean?

High CRP levels often indicate inflammation, which can be caused by infections, injuries, or certain medical conditions. Low levels usually mean your body is not actively inflamed, but this can vary based on your overall health and specific context.

How Is the Test Performed?

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

What Should You Expect Before or After the Test?

There are usually no special preparations needed for this test. You may feel slight discomfort or bruising at the needle insertion site, but this typically goes away quickly. If you have a blood clot disorder or are on certain medications, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (like colds or flu), injuries, surgeries, or certain medical conditions such as arthritis, heart disease, or autoimmune disorders. They can also be influenced by factors like stress, smoking, or certain medications. CRP levels typically return to normal once the underlying cause is treated.
How often should I get this test?
The frequency of CRP testing depends on your medical condition and treatment plan. Your doctor will determine how often you need this test based on your specific needs, such as monitoring chronic diseases or evaluating responses to treatments.
Can lifestyle changes affect CRP levels?
Yes, lifestyle factors like diet, exercise, smoking, and stress can influence CRP levels. Maintaining a healthy diet, staying physically active, avoiding smoking, and managing stress may help lower CRP levels and reduce inflammation in your body.
  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