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C-reactive protein, mass concentration (serum/plasma)

Published: August 9, 2026Updated: August 17, 2026

This test measures the level of C-reactive protein in your blood, which is a marker often used to check for inflammation or infection.

Quick summary

["CRP helps doctors assess whether your body is responding to an injury, illness, or infection."]

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

Key facts at a glance

LOINC
104680-4
Short code
DMA 18:0 RBC-mCnc
Synonyms
DMA 18:0 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

What Is C-Reactive Protein (CRP) Used For?

CRP is commonly used to monitor conditions like arthritis, heart disease, or infections. It can also help track how well treatment is working or if inflammation is worsening. Some doctors use it to guide decisions about medications or further testing.

How Is CRP Tested?

Your blood sample is taken from a vein in your arm. The lab then measures the amount of CRP in your serum or plasma using a sensitive test that detects protein levels.

What Does a High CRP Level Mean?

Elevated CRP levels often indicate inflammation, which can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (like rheumatoid arthritis), or other conditions causing stress on your body.

What Does a Low CRP Level Mean?

Low CRP levels usually mean there is little to no inflammation in your body. However, very low levels might raise questions about underlying conditions that need further evaluation.

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

Frequently asked questions

Why might my CRP test be ordered?
Your doctor may order a CRP test to check for signs of inflammation, monitor chronic conditions, evaluate symptoms like fever or joint pain, or assess the risk of heart disease or other inflammatory diseases.
Can CRP levels change with diet or exercise?
Yes, lifestyle factors like diet, exercise, and stress can influence CRP levels. Eating a healthy diet, staying active, and managing stress may help lower CRP levels over time.
What are some common conditions linked to high CRP levels?
High CRP levels are often seen in infections, autoimmune diseases (like lupus or inflammatory bowel disease), heart disease, and other inflammatory or autoimmune conditions.
  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