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C-reactive protein, mass concentration (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 in your body.

Quick summary

["CRP helps doctors identify and monitor inflammation, often used to check for infections or other inflammatory conditions."]

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

Key facts at a glance

LOINC
87474-3
Short code
Cr Spec-mCnt
Synonyms
Cr Spec-mCnt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 infection, such as pneumonia or urinary tract infections, or to monitor conditions like rheumatoid arthritis, heart disease, or other inflammatory diseases. It can also help assess how your body is responding to treatment for these conditions.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into a vein in your arm to draw blood. If you’re concerned about needles, let your healthcare provider know so they can offer comfort measures.

What the Results Mean

Higher than normal CRP levels often indicate inflammation or infection. Lower levels may suggest reduced inflammation. Your results will be compared to a reference range provided by your healthcare provider to determine if further action is needed.

Common Conditions Monitored

CRP is commonly used to monitor conditions like autoimmune diseases (e.g., lupus, rheumatoid arthritis), infections, and after surgeries or injuries to track healing progress.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (like colds or flu), injuries, surgeries, or certain medications. They may also be higher in people with autoimmune diseases or chronic conditions like heart disease. Stress or certain foods can temporarily affect CRP levels, but this is less common.
How often should I get this test?
Your healthcare provider will determine how often you need this test based on your health condition, symptoms, and treatment plan. Some people get it yearly, while others may need it more frequently if they have ongoing inflammation or a chronic condition.
Can diet or lifestyle affect CRP levels?
While diet and lifestyle factors like smoking, obesity, or physical activity can influence inflammation, CRP levels are primarily measured as a snapshot of your body’s response. Small dietary changes (e.g., reducing processed foods) may help lower inflammation over time, but this test alone doesn’t show direct dietary effects.
  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