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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 in your blood, a protein produced by your liver in response to inflammation.

Quick summary

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

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

Key facts at a glance

LOINC
10445-5
Short code
CD11c
Synonyms
CD11c Ag Tiss Ql ImStn
Category
chemistry
Sample
serum
Container
Sterile container with 10% neutral buffered formalin for tissue fixation; paraffin block or unstained tissue sections on charged/adhesive glass slides for submitted slides
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
immune-stain
CPT
88342
SNOMED
395143002
Specimen volume
Tissue biopsy or resection specimen of adequate size to represent the lesion (minimum 3-4 mm); for slides, typically 4-5 unstained sections (3-5 microns thick) on positively charged slides
Stability
Formalin-fixed tissue: indefinite at room temperature once processed and paraffin-embedded. Unstained slides: stable for up to 6 months at room temperature. Fresh tissue should be placed in formalin promptly (within 30-60 minutes) for optimal antigen preservation.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order a CRP test to check for signs of inflammation, monitor chronic conditions (such as rheumatoid arthritis or heart disease), or evaluate symptoms like fever, joint pain, or unexplained fatigue. It can also help guide treatment decisions for infections or inflammatory disorders.

What to Expect Before the Test

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

What to Expect During the Test

The blood draw typically takes a few minutes. You might feel a slight pinch, but most people tolerate it well. If you’re anxious, ask about numbing cream or other options.

What the Results Mean

Higher than normal CRP levels often indicate inflammation, infections, or other health issues. Lower levels suggest minimal inflammation. Your provider will interpret results in the context of your medical history and symptoms.

Reference range

Reported as Positive (staining present) or Negative (staining absent). Staining pattern is typically membranous and/or cytoplasmic. Intensity is graded on a scale of 0 (negative), 1+ (weak), 2+ (moderate), or 3+ (strong). Percentage of positive cells may also be reported. Normal interpretation depends on tissue type; CD11c is normally expressed on dendritic cells, monocytes, macrophages, neutrophils, and some NK cells.N/A

Specimen: serum

No patient preparation required. Tissue specimen collection is performed by biopsy or surgical excision by the clinical team. Standard surgical pathology specimen handling applies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a marker for systemic inflammation. Elevated levels may signal infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., lupus, rheumatoid arthritis), or other inflammatory conditions. It can also be used to monitor response to treatment or assess risk for conditions like heart disease.

Short name

CRP

Frequently asked questions

What causes CRP levels to rise?
CRP levels can increase due to infections (like colds, flu, or urinary tract infections), injuries, surgeries, or certain medical conditions such as autoimmune diseases (e.g., rheumatoid arthritis). Stress, smoking, or certain medications may also affect CRP levels.
How often should I get a CRP test?
Your provider will determine how often you need a CRP test based on your health needs. Some people get it yearly for monitoring, while others may need it more frequently if they have ongoing conditions like heart disease or arthritis.
Can CRP levels be affected by diet or lifestyle?
Yes, diet and lifestyle can influence CRP levels. Eating a heart-healthy diet, managing weight, exercising regularly, and avoiding smoking may help lower CRP levels. Stress reduction and adequate sleep also play a role in reducing inflammation.
  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