Skip to content

C-reactive protein (CRP) concentration in serum/plasma

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

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

Quick summary

["CRP helps doctors check for inflammation, infections, or other health issues."]

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

Key facts at a glance

LOINC
81566-2
Short code
NM Hrt Gat+BP+EF+WM W mult exer+W RNC IV
Synonyms
NM Hrt Gat+BP+EF+WM W mult exer+W RNC IV
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nm
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 Is Done

Your doctor may order a CRP test to monitor conditions like arthritis, heart disease, infections, or to check for signs of inflammation after surgery or injury. It can also help track how well treatments are working for certain conditions.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein in your arm to draw blood. If you’re concerned about needles, let your doctor or nurse know.

What the Results Mean

Higher CRP levels often indicate inflammation, but they can also be raised due to infections, stress, or other health problems. Your doctor will compare your results to your medical history and other tests to understand what they mean for you.

Common Conditions Monitored

CRP is used to assess inflammation in conditions like rheumatoid arthritis, lupus, heart disease, or after surgeries to see how your body is healing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a marker for systemic inflammation. Elevated levels can signal infections, autoimmune diseases, or other inflammatory processes, guiding treatment decisions or monitoring disease activity.

Short name

CRP (Serum/Plasma)

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (like a cold or flu), injuries, surgeries, or certain medical conditions like autoimmune diseases. Stress, smoking, or certain medications can also affect CRP levels.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition and treatment plan. Some people get it regularly to monitor inflammation, while others may need it only if symptoms appear.
Can diet or lifestyle affect CRP levels?
Yes, diet, exercise, and weight management can influence CRP levels. Eating a heart-healthy diet, staying active, and maintaining a healthy weight may help lower 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