Skip to content

C-reactive protein, serum/plasma mass concentration

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 the body.

Quick summary

["CRP helps identify and monitor inflammation, often used to check for infections, autoimmune conditions, or other inflammatory diseases."]

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

Key facts at a glance

LOINC
21200-1
Short code
Cr Nail-mCnt
Synonyms
Cr Nail-mCnt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 evaluate signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or check for infections such as pneumonia or sepsis. It can also help assess the effectiveness of treatments for inflammatory diseases.

What to Expect During the Test

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch when the needle is inserted, but the process is quick. No special preparation is typically needed unless directed by your provider.

Common Uses and Conditions

CRP is commonly used to monitor conditions like heart disease, where inflammation plays a role, or to guide decisions about starting or stopping certain medications. It can also help diagnose or track conditions like kidney disease or certain infections.

When Might You Need Follow-Up?

If your CRP levels are elevated, your provider may recommend additional tests or treatments to address the underlying cause of inflammation. Regular follow-ups may be scheduled to monitor changes in your levels over time.

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 suggests your body is experiencing inflammation. This could be due to infections, autoimmune diseases, or other inflammatory conditions. Your healthcare provider will use the results along with other information to determine the best course of action.
What does a low CRP level mean?
A low CRP level generally indicates low levels of inflammation in your body. However, it doesn’t rule out all possible causes of symptoms. If you have ongoing health concerns, further evaluation may still be necessary.
How often should I get this test?
The frequency of CRP testing depends on your medical condition and your healthcare provider’s recommendations. Some people may need it regularly to monitor chronic inflammatory diseases, while others may only need it occasionally for specific situations.
  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