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C-reactive protein (CRP) measured by nephelometry 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 or autoimmune diseases."]

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

Key facts at a glance

LOINC
105788-4
Short code
OXA58
Synonyms
Carbpnm res blaOXA58 Ct Bld +Qn NAA prb
Category
chemistry
Sample
whole-blood
Container
Positive blood culture broth bottle (aerobic or anaerobic); transfer to sterile nucleic acid transport tube if required by testing platform
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
CPT
87641
SNOMED
447916003
Specimen volume
1-2 mL aliquot from positive blood culture bottle
Stability
Ambient: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-70°C): 30 days. Process as soon as possible after blood culture flags positive.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
2–8 hours
Order
routine

Why CRP Matters in Your Health

CRP is a marker that signals when your body is fighting inflammation. High levels may indicate conditions such as infections, injuries, or certain inflammatory diseases.

Common Uses of CRP Testing

Doctors may order CRP tests to check for infections (like pneumonia or sepsis), evaluate autoimmune conditions (such as rheumatoid arthritis), or monitor chronic diseases like heart disease.

How the Test Works

Blood is drawn and sent to a lab where it is analyzed using nephelometry, a method that detects the protein’s presence and concentration in your serum or plasma.

What to Expect Before the Test

No special preparation is needed, but you may want to avoid strenuous exercise 24 hours before the test, as it could temporarily raise CRP levels.

Reference range

Negative (Ct value not detected); Cycle threshold (Ct) values are reported when positive for blaOXA-58 carbapenemase gene detection. Lower Ct values generally indicate higher bacterial load.N/A

Specimen: whole-blood

No special patient preparation required. Specimen should be collected prior to initiation of antimicrobial therapy when possible for optimal diagnostic yield. Standard aseptic blood culture collection technique must be followed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP Levels and Health

Short name

CRP (Nephelometry)

Frequently asked questions

What does a high CRP level mean?
A high CRP level often suggests inflammation or infection. However, it can also be elevated due to other factors like stress, certain medications, or obesity. Your doctor will consider your overall health and symptoms to interpret results.
Can low CRP levels indicate anything specific?
Low CRP levels generally mean there is less inflammation in your body. However, very low levels might raise concerns if you have a chronic inflammatory condition, as it could indicate poor disease control or a need for further investigation.
How often should CRP be checked?
The frequency of CRP testing depends on your medical condition. For example, people with heart disease or autoimmune disorders may have CRP checked regularly, while others may only need it if symptoms suggest inflammation.
  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