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C-reactive protein (CRP) by electrochemiluminescence immunoassay (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, autoimmune conditions, or other health concerns."]

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

Key facts at a glance

LOINC
95939-5
Short code
Fet CRL US Prctl per est GA
Synonyms
Fet CRL US Prctl per est GA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
per-estimated-gestational-age
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 monitor conditions like infections, arthritis, heart disease, or other inflammatory disorders. It can also help track how well treatment is working or check for signs of new inflammation after starting treatment.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Avoid strenuous activity or excessive alcohol the day before. Let your provider know about any medications you’re taking, as some may affect results.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but it’s usually over quickly. The blood sample is then sent to a lab for testing using a sensitive immunoassay method to detect CRP levels.

What Do the Results Mean?

Results are reported in milligrams per liter (mg/L) or micrograms per milliliter (µg/mL). Higher than normal levels may indicate inflammation, infection, or an autoimmune condition. Your provider will interpret results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

How often will I need this test?
Your provider will determine how often you need CRP testing based on your medical history, symptoms, and treatment plan. Some people get it every few months to monitor chronic conditions, while others may only need it once.
What can affect my CRP levels?
Several factors can influence CRP levels, including infections, injuries, stress, certain medications (like steroids), smoking, or even recent physical activity. Avoiding these triggers before testing can help get a more accurate result.
Can I eat or drink before this test?
If your blood is drawn early in the morning, fasting for 8–12 hours is usually recommended. Otherwise, you can eat and drink normally unless instructed otherwise by your provider.
  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