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C-reactive protein (CRP) by nephelometry

Published: August 9, 2026Updated: August 17, 2026

This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation in your body.

Quick summary

["CRP helps identify and monitor inflammation, often used to check for infections or other inflammatory conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
34200-6
Short code
nRBC Bld Ql Auto
Synonyms
nRBC Bld Ql Auto
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
automated-count
CPT
85041
SNOMED
900000000000003001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why CRP is Tested

Doctors may order CRP tests to evaluate symptoms like fever, pain, or swelling that suggest an infection, autoimmune disease, or other inflammatory process. It can also be used to monitor chronic conditions such as arthritis or heart disease.

How the Test Works

Your blood sample is analyzed using nephelometry, a method that measures how much light is scattered by proteins in your blood. This helps determine the concentration of CRP.

Sample Collection

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch, but it typically doesn’t cause significant discomfort. The sample is sent to the lab for testing.

Preparation for the Test

No special preparation is needed for this test. You can eat and drink normally on the day of your appointment.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

What are the normal results of a CRP test?
Normal results vary and are interpreted based on your overall health and medical history. Your healthcare provider will discuss the results with you and explain what they mean for your specific situation.
Can CRP levels change with diet or exercise?
Diet and exercise can influence inflammation indirectly. Certain foods may help reduce inflammation, but CRP levels alone don’t directly reflect dietary habits. Your doctor may recommend lifestyle changes if inflammation is elevated.
How often should I get a CRP test?
The frequency of CRP testing depends on your medical condition and treatment plan. Your healthcare provider will determine how often you need this test based on your needs and symptoms.
  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 17, 2026. · Read our editorial policy