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C-reactive protein (CRP) by nephelometry

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 in your body.

Quick summary

["CRP helps identify inflammation that may be causing symptoms like pain, swelling, or fever."]

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

Key facts at a glance

LOINC
95203-6
Short code
CD107ab CD8 PMA/iono
Synonyms
CD107ab CD8/CD3+CD8+ NFr Bld FC
Category
chemistry
Sample
whole-blood
Container
Heparin (sodium or lithium heparin) green-top tube preferred for functional flow cytometry assays; EDTA (lavender-top) may be acceptable but heparin preferred for lymphocyte functional studies
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
flow-cytometry
CPT
86356 (Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only); additional units may apply for stimulation and functional marker analysis (88184, 88185)
SNOMED
440317004 (Flow cytometry procedure); 122558005 (CD8-positive T-lymphocyte)
Specimen volume
3-5 mL of whole blood; minimum 1 mL for pediatric samples
Stability
Process within 8-24 hours of collection when stored at room temperature (18-25°C); do not refrigerate; specimen should be processed as soon as possible to maintain cell viability and function
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test to check for signs of inflammation, monitor conditions like infections, autoimmune diseases, or after surgery. It can also help track 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 your arm to draw blood. If you’re concerned about needles or have a blood disorder, let your healthcare provider know.

What the Results Mean

Higher CRP levels often indicate inflammation, but they can also be elevated due to other factors like infections, stress, or certain medications. Your doctor will interpret results in the context of your overall health and symptoms.

Common Conditions Monitored

This test is commonly used to monitor conditions such as rheumatoid arthritis, lupus, heart disease, or infections like pneumonia. It can also help assess response to treatments for these conditions.

Reference range

Reference values are laboratory- and population-specific. Results are typically reported as percentage of CD107a+b expressing CD8+ T cells among total CD3+CD8+ T lymphocytes after stimulation. Generally established in-house by each laboratory using healthy donor controls.N/A

Specimen: whole-blood

No special patient preparation required. Fasting is not required. Patients on immunosuppressive medications should be noted as results may be affected. Avoid recent vaccination or acute illness when possible, as immune activation status may alter results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

What causes CRP levels to be higher than usual?
CRP can rise due to infections (like a cold or flu), injuries, surgeries, or certain medical conditions such as autoimmune diseases. Stress, obesity, or some medications may also influence CRP levels.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time. Your doctor will discuss the findings with you during your follow-up visit.
Can diet or lifestyle affect CRP levels?
Yes, diet, exercise, and weight management can influence CRP levels. Reducing processed foods, increasing omega-3 fatty acids (found in fish), and maintaining a healthy weight may help lower CRP levels over time.
  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