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C-reactive protein (CRP) by high-performance liquid chromatography (HPLC) or nephelometry

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

This test measures the level of C-reactive protein, a protein made by your liver that rises 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 17, 2026Editorial policy

Key facts at a glance

LOINC
111020-4
Short code
c-ANCA
Synonyms
c-ANCA Msmt Ser
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube
Units
N/A
Critical range
0.5 N/A – —
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Immunoassay (e.g., ELISA, chemiluminescent immunoassay, or indirect immunofluorescence)
CPT
83520
SNOMED
313324003
Specimen volume
1-2 mL of serum
Stability
Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
24–72 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help diagnose infections or identify risks for conditions like heart disease.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re concerned about needles, let your healthcare provider know.

What the Results Mean

Higher than expected levels may indicate inflammation, infections, or other health issues. Lower levels might suggest reduced inflammation, but they don’t always mean you’re healthy. Your doctor will interpret results in the context of your medical history.

Common Conditions Monitored

CRP is often used to track conditions like rheumatoid arthritis, lupus, or heart disease. It can also help guide decisions about treatments or infections.

Reference range

Negative (antibodies not detected); result reported as positive or negative with titer if positiveN/A

Specimen: serum

No fasting required. Patient should inform the clinician of any current immunosuppressive therapy, as it may affect antibody titers

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum)

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (like colds or flu), injuries, surgeries, or certain medical conditions (like autoimmune diseases). Stress, smoking, or certain medications may also affect results.
How soon will I get my results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss them with you.
Can I eat or drink before this test?
You can eat and drink normally. Avoiding food or fluids for this test isn’t required.
  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