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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 made by your liver in response to inflammation in your body.

Quick summary

["CRP helps doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
50841-6
Short code
Cr RBC-sCnc
Synonyms
Cr RBC-sCnc
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
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 is CRP tested?

Doctors may order CRP tests to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate responses to treatments. It can also help diagnose infections or identify risks for heart disease.

What does a high CRP level mean?

A higher-than-normal CRP level often indicates inflammation or infection. While it doesn’t specify the cause, it can guide treatment decisions and help track how well your body is responding to treatment over time.

What does a low CRP level mean?

A low CRP level suggests minimal inflammation. However, it doesn’t rule out all causes of inflammation, so doctors may use it alongside other tests for a full picture.

How is CRP tested?

This test uses a method called nephelometry, which measures how much light is scattered by CRP particles in your blood sample. It’s typically done on a blood sample drawn from your arm.

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.

CRP is a useful marker for inflammation, which can occur in many conditions, from minor infections to serious diseases like heart disease or cancer. It’s often used as a screening tool, especially in people at higher risk for cardiovascular issues. However, CRP alone isn’t diagnostic—it’s usually part of a broader evaluation.

Short name

CRP (Neph)

Frequently asked questions

What does it mean if my CRP level is elevated?
An elevated CRP level suggests inflammation is present, but it doesn’t tell you the exact cause. Common reasons include infections, autoimmune diseases, or other inflammatory conditions. Your doctor may recommend further testing or adjustments to your treatment plan based on the results.
How often should I get CRP tested?
The frequency depends on your health condition and why the test was ordered. If you have a chronic condition like rheumatoid arthritis, your doctor may recommend regular monitoring. For general health checks, CRP testing isn’t typically routine unless you have risk factors for inflammation or heart disease.
Can CRP levels change with diet or lifestyle?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. Reducing inflammation through healthy eating, managing stress, and avoiding smoking may help lower CRP levels over time. However, CRP is primarily a marker of current inflammation, not a direct measure of lifestyle impact.
  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