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

Published: August 9, 2026Updated: August 17, 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 assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
5621-8
Short code
Cr RBC-mCnc
Synonyms
Cr RBC-mCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why CRP Levels Matter

CRP is a marker for inflammation, which can signal infections, injuries, or other health issues. High levels may indicate an active inflammatory process, while low levels suggest reduced inflammation.

What Can Cause Changes in CRP Levels?

Elevated CRP levels can be caused by infections (such as pneumonia or urinary tract infections), autoimmune diseases (like rheumatoid arthritis), heart disease, or other inflammatory conditions. Stress, certain medications, or recent trauma may also temporarily affect results.

When Might You Need This Test?

Your doctor may order CRP testing to monitor chronic conditions, check for infections, evaluate response to treatment, or assess risk for heart disease or other inflammatory disorders.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about recent illnesses, medications, or conditions that could affect results. Avoid strenuous activity 24 hours before testing if instructed.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

What does a high CRP level mean?
A high CRP level often signals inflammation or infection, but it can also be influenced by other factors like stress, recent illness, or certain medications. Your doctor will consider your overall health and symptoms to interpret results.
Can diet or exercise affect CRP levels?
While diet and exercise can influence inflammation, they do not directly alter CRP test results. However, maintaining a healthy lifestyle may help manage conditions linked to CRP, such as heart disease or arthritis.
How long does it take to get CRP test results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time. Your doctor will discuss the findings with you during your follow-up visit.
  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 17, 2026. · Read our editorial policy