Skip to content

C-reactive protein (CRP) concentration in 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 the body.

Quick summary

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

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

Key facts at a glance

LOINC
49350-2
Short code
CMV DNA # Mar NAA+probe
Synonyms
CMV DNA # Mar NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 CRP Matters in Your Health

CRP is a marker for inflammation, which is the body’s way of responding to injury, infection, or illness. High levels may signal conditions like infections, arthritis, or heart disease. Your doctor may order this test to check for inflammation or monitor a known condition.

When This Test Is Done

Doctors often request CRP tests to evaluate symptoms like fever, joint pain, or swelling. It may also be used before surgery to assess risk or after treatment to monitor recovery. Some conditions, like rheumatoid arthritis or heart disease, are tracked with regular CRP checks.

What to Expect During the Test

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch, but it’s quick and painless. The blood is sent to a lab for analysis. Results are typically ready within a few days.

What the Results Mean

Results are compared to a general reference range, but what’s normal can vary by lab. Very high CRP levels may indicate severe inflammation, while very low levels might suggest reduced immune response. Your doctor will interpret results in the context of your health history and other tests.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Plasma)

Frequently asked questions

What causes elevated CRP levels?
Elevated CRP can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (like lupus or rheumatoid arthritis), heart disease, or other inflammatory conditions. It can also rise after surgery, trauma, or certain medications.
What causes low CRP levels?
Low CRP levels may occur in people with chronic, well-controlled inflammatory conditions, those with certain infections (like tuberculosis), or those taking anti-inflammatory medications. Very low levels could also indicate a suppressed immune response.
Can CRP levels change over time?
Yes, CRP levels can fluctuate based on activity, diet, stress, or underlying health changes. If your doctor orders CRP regularly, results may be compared over time to track trends in 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