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

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 track inflammation in your body."]

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

Key facts at a glance

LOINC
6918-7
Short code
C trach IgA Titr Ser IF
Synonyms
C trach IgA Titr Ser IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82784
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 This Test Might Be Ordered

Your healthcare provider may order this test to monitor conditions like infections, autoimmune diseases, or after surgery to check for signs of inflammation or infection. It can also help assess how well treatments are working for conditions like arthritis or heart disease.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein (usually in your arm) to draw blood. If you’re on blood thinners, let your provider know before the test.

What the Test Results Mean

Higher-than-normal CRP levels may indicate inflammation, infection, or other health issues. Your results will be compared to a reference range provided by your lab, but exact values depend on the test method and lab standards.

Common Conditions Monitored

This test is often used to diagnose or track conditions such as rheumatoid arthritis, lupus, heart disease, or infections like pneumonia or sepsis. It can also help evaluate responses to treatments for these conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

What factors could affect my CRP levels?
Several factors may influence CRP levels, including recent infections, injuries, stress, certain medications (like steroids), or underlying health conditions. Smoking, obesity, and poor diet can also play a role. If you suspect these factors may affect your results, discuss them with your provider.
How soon will I get my results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time. Your provider will explain the results and next steps during your follow-up visit.
Can I eat or drink before this test?
You can eat and drink normally before this test unless instructed otherwise by your provider. Blood tests like this one do not require fasting unless specified for other reasons.
  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