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C-reactive protein, serum concentration measured by nephelometry

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of C-reactive protein (CRP) in your blood. CRP is a protein produced by your liver in response to inflammation, helping your body identify and fight infections or injuries.

Quick summary

["CRP helps doctors assess inflammation, which can signal infections, autoimmune conditions, or other health issues."]

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

Key facts at a glance

LOINC
45096-5
Short code
C trach Nph Ql Cult
Synonyms
C trach Nph Ql Cult
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
organism-specific-culture
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

What Is CRP Used For?

CRP is commonly used to monitor inflammation in conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis), or after surgeries or injuries. It can also help track response to treatments.

Why Might You Need This Test?

Your doctor may order CRP testing if you have symptoms like fever, pain, or swelling; if you’re recovering from an illness; or if you have a chronic condition requiring inflammation monitoring. It’s also sometimes checked as part of a general health evaluation.

How Is the Test Performed?

A blood sample is drawn from a vein in your arm. The blood is sent to a lab, where it’s analyzed using nephelometry—a method that measures how much CRP is present in your serum.

What Are Common Results?

Results are reported in milligrams per liter (mg/L). Higher levels may indicate active inflammation, while lower levels suggest reduced inflammation. Your doctor will interpret results based on your specific situation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum)

Frequently asked questions

What does a high CRP level mean?
A high CRP level often means your body is responding to inflammation, which could be due to infections, injuries, or autoimmune diseases. Your doctor will discuss this with you and may recommend additional tests or treatments.
How often should I get CRP tested?
The frequency depends on your health needs. Your doctor will determine how often you need testing based on your symptoms, medical history, and treatment plan.
Can CRP levels change with diet or exercise?
Yes, lifestyle factors like diet, exercise, and stress can influence CRP levels. Reducing inflammation through healthy habits may lower CRP over time, but results vary by individual.
  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