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C-reactive protein (CRP) by nephelometry in serum/plasma

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

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

Quick summary

["CRP helps doctors assess inflammation, track infections, or monitor conditions like arthritis or heart disease."]

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

Key facts at a glance

LOINC
94633-5
Short code
C parvum DNA Ct Spec Qn NAA+probe
Synonyms
C parvum DNA Ct Spec Qn NAA+probe
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 healthcare provider may order this test to check for signs of inflammation, monitor chronic conditions (such as rheumatoid arthritis or heart disease), or evaluate recent infections or injuries. CRP levels can also help guide treatment decisions.

What Does a High CRP Level Mean?

Elevated CRP levels often indicate inflammation, which can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (such as lupus or rheumatoid arthritis), or other inflammatory conditions. However, CRP alone isn’t diagnostic—your provider will consider other factors.

What Does a Low CRP Level Mean?

Low CRP levels usually suggest minimal inflammation. In some cases, they may indicate good control of chronic conditions or recovery from an acute illness. However, very low levels can sometimes be normal or may require further evaluation if symptoms persist.

How Is This Test Performed?

A blood sample is drawn from a vein in your arm. The sample is sent to a lab where it is analyzed using nephelometry, a method that measures how particles scatter light to detect CRP levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a non-specific marker of inflammation. While it doesn’t identify the cause of inflammation, it helps monitor trends over time, assess response to treatment, or guide decisions about further testing (e.g., for infections or autoimmune disorders).

Short name

CRP (Nephelometry)

Frequently asked questions

Why might my CRP test be ordered?
Your doctor may order this test to check for inflammation, evaluate symptoms like joint pain or fever, monitor chronic conditions, or assess risk for heart disease or other inflammatory conditions.
What are common reference ranges?
Reference ranges vary by lab and individual health. Typically, low CRP levels are below 1 mg/L, mild inflammation may range up to 3 mg/L, and higher levels (above 10 mg/L) may indicate severe inflammation. Your results will be interpreted by your healthcare provider.
Can CRP levels change with diet or exercise?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. Reducing inflammation through healthy habits may lower CRP, but this test alone doesn’t replace medical evaluation for underlying causes.
  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