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C-reactive protein (CRP) concentration, mass concentration

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

This test measures the amount of C-reactive protein in your blood. CRP is a protein produced by your liver in response to inflammation or infection.

Quick summary

["CRP helps doctors assess inflammation, which can signal infection, injury, or other health issues."]

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

Key facts at a glance

LOINC
28539-5
Short code
MCH RBC Qn
Synonyms
MCH RBC Qn
Category
hematology
Sample
serum
Container
Red-top tube (SST)
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
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

Doctors may order a CRP test to monitor conditions like arthritis, heart disease, or infections. It can also help track how well treatments are working or check for hidden inflammation in your body.

What to Expect Before the Test

You may not need special preparation. If you’re taking blood from your arm, tell your healthcare provider about any medications or supplements you’re taking to avoid unnecessary delays.

What the Results Mean

Higher CRP levels often mean inflammation is present, but the exact meaning depends on your overall health and symptoms. Your doctor will interpret results in the context of your medical history.

Common Conditions Linked to CRP

Elevated CRP can signal conditions like infections (e.g., pneumonia), autoimmune diseases (e.g., rheumatoid arthritis), or heart problems. Low or normal levels may indicate stable health or no active inflammation.

Reference range

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

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP Level

Frequently asked questions

What causes CRP to be elevated?
Elevated CRP can result from infections (like bacterial or viral), injuries, surgeries, or certain medical conditions such as autoimmune diseases. Stress or recent illness may also temporarily raise levels.
Can CRP levels change over time?
Yes, CRP levels can fluctuate based on your health status. Regular monitoring helps track trends, especially if you have chronic conditions like heart disease or arthritis.
Does diet affect CRP levels?
Diet can influence inflammation indirectly. Eating a balanced diet rich in fruits, vegetables, and omega-3s may support lower CRP levels, but results depend on overall health and other factors.
  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