Skip to content

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 in your body.

Quick summary

["CRP helps doctors check for inflammation, which can signal infections, injuries, or other health issues."]

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

Key facts at a glance

LOINC
44995-9
Short code
C trach B IgG Ser Ql
Synonyms
C trach B IgG Ser Ql
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 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 track how well treatments are working.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s part of a fasting panel, but this depends on your doctor’s instructions. Bring any medications you’re taking to your appointment.

During the Test

A healthcare provider will draw blood from a vein in your arm. You may feel a small pinch, but it usually doesn’t cause significant discomfort. The blood sample is sent to a lab for analysis.

What the Results Mean

Higher-than-normal CRP levels may indicate inflammation, but they can also be influenced by factors like stress, recent illness, or certain medications. Your doctor will interpret the results in the context of your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (bacterial or viral), injuries, surgeries, or autoimmune conditions. They may also be affected by factors like smoking, obesity, or certain medications. Stress or recent illness can temporarily increase CRP as well.
How often should I get this test?
Your doctor will determine how often you need a CRP test based on your health condition. Some people get it every few months to monitor chronic inflammation, while others may only need it once for a specific reason.
Can CRP levels be affected by diet or exercise?
Yes, lifestyle factors like diet (e.g., Mediterranean diet) and exercise can influence CRP levels. Reducing processed foods, increasing fruits/vegetables, and staying active may help lower inflammation over time, but CRP results alone shouldn’t guide diet changes without medical advice.
  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