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C-reactive protein (CRP) by nephelometry

Published: August 9, 2026Updated: August 16, 2026

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

Quick summary

["CRP helps doctors monitor inflammation, guide treatment, and assess risk for conditions like heart disease."]

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

Key facts at a glance

LOINC
23291-8
Short code
M myc my sc Ag Spec Ql IF
Synonyms
M myc my sc Ag Spec Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 doctor may order CRP testing to evaluate symptoms like fever, joint pain, or swelling, or to monitor chronic conditions like arthritis or heart disease. It can also help determine if an infection is present or if inflammation is worsening.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or hand to draw blood. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Higher-than-normal CRP levels may indicate inflammation, infections, or autoimmune diseases. Lower levels might suggest reduced inflammation, but results depend on your overall health and symptoms.

Common Conditions Monitored

CRP is used to track conditions like rheumatoid arthritis, heart attacks, or infections (e.g., pneumonia). It’s also part of screening for cardiovascular risks.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

What causes CRP levels to change?
CRP rises with infections, injuries, or autoimmune diseases. It may also increase with stress, certain medications, or pregnancy. It can drop with treatment for inflammation or recovery from illness.
How often should I get this test?
Your doctor will determine frequency based on your health needs. Some people get it every few months to monitor chronic conditions, while others may need it only occasionally.
Can diet or exercise affect CRP levels?
Yes! Reducing inflammation through diet (e.g., Mediterranean diet), exercise, and avoiding smoking can lower CRP levels. Stress management also plays a role.
  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