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C-reactive protein (CRP) concentration in 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 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
48813-0
Short code
mecA Islt/Spm Ql
Synonyms
mecA Islt/Spm Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
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 a CRP test to check for signs of inflammation. This could be due to suspected infections (like pneumonia or urinary tract infections), autoimmune conditions (such as rheumatoid arthritis), or after procedures to monitor healing. It may also be used to evaluate symptoms like fever, joint pain, or unexplained fatigue.

What Does a High CRP Level Mean?

Elevated CRP levels often indicate inflammation. While high CRP can be caused by infections, it can also appear in conditions like arthritis, heart disease, or certain cancers. Low or normal CRP levels suggest minimal inflammation, but they don’t rule out all causes of symptoms.

What Does a Low CRP Level Mean?

Low CRP levels usually mean there is little to no active inflammation. However, very low levels might not always indicate a healthy state, especially if you have a chronic condition. Always discuss results with your doctor.

How Is This Test Performed?

A blood sample is taken from a vein in your arm. The blood is then sent to a lab where it is analyzed using an immunoassay method to measure CRP levels accurately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a sensitive marker for inflammation and is widely used in clinical practice. It can help diagnose infections, monitor disease activity in autoimmune disorders, and assess the risk of cardiovascular events. While CRP is not specific to any single condition, it provides important context for further evaluation and treatment planning.

Short name

CRP (Serum/Plasma)

Frequently asked questions

What are the typical reference ranges for CRP?
CRP reference ranges vary by lab and individual health status. Typically, low CRP levels (below 1 mg/L) suggest minimal inflammation, while moderate (1–3 mg/L) or high levels (above 3 mg/L) may indicate more significant inflammation. Your doctor will interpret results in the context of your symptoms and medical history.
How long does it take to get CRP test results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing times. If you have an urgent concern, contact your healthcare provider for updates on turnaround times.
Can lifestyle changes affect CRP levels?
Yes, lifestyle factors like diet, exercise, smoking, and stress can influence CRP levels. Reducing inflammation through healthy habits—such as eating anti-inflammatory foods, staying active, and avoiding smoking—may help lower CRP levels over time. Always consult your doctor before making significant lifestyle changes.
  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