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Serum or plasma concentration of C-reactive protein (CRP) measured by nephelometry

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

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

Quick summary

["CRP helps your doctor track inflammation in your body."]

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

Key facts at a glance

LOINC
48035-0
Short code
Hgb CSF Ql
Synonyms
Hgb CSF Ql
Category
hematology
Sample
csf
Container
Sterile tube
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order CRP testing to check for signs of inflammation, infections, or conditions like autoimmune diseases, heart disease, or kidney problems. It can also help monitor how well treatments are working.

What Does a High CRP Level Mean?

Elevated CRP levels often indicate inflammation, which can be caused by infections, injuries, or certain medical conditions. However, a single high reading doesn’t always confirm a specific diagnosis.

What Does a Low CRP Level Mean?

Low CRP levels usually mean there is little to no inflammation in your body. This can be normal, but it may also suggest conditions like certain autoimmune diseases or chronic infections where inflammation is suppressed.

How Is This Test Performed?

A blood sample is taken 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 scatters from CRP particles in the sample.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: csf

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

What does a CRP test measure?
A CRP test measures the amount of C-reactive protein in your blood. This protein is produced by your liver and rises when your body is inflamed or fighting infection.
Can CRP levels change with diet or exercise?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. For example, certain foods, weight management, and avoiding smoking may help lower CRP.
How often should I get a CRP test?
The frequency of CRP testing depends on your health condition and medical needs. Your doctor will determine how often you need it based on your symptoms, medical history, and other test results.
  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