C-Reactive Protein Test (standard and high sensitivity)

What is C-Reactive Protein?

C-reactive protein (CRP) is a protein produced by the liver in response to inflammation. It circulates in the blood and is an indicator of inflammation and infection.

CRP increases inflammation, which is necessary to fight infection, protect tissues, and support healing. However, an exaggerated or long-term inflammatory response can cause tissue damage, leading to chronic diseases. Accumulation of CRP in inflamed or injured tissues can accelerate tissue injury.

What is a C-Reactive Protein test?

The CRP test measures the level of CRP in the blood. There are two main types of CRP test: the standard CRP test and the high-sensitivity CRP (hsCRP) test.

The hsCRP test is more sensitive than the standard test, detecting lower concentrations of CRP than the standard test and providing greater precision at low CRP levels.

The standard CRP test is used to measure short-term (acute) sudden, severe cases of inflammation (e.g., infection, injury, surgery, and flare-ups of autoimmune diseases) and the level of inflammation in long-term (chronic) active inflammatory conditions (e.g., autoimmune diseases, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and inflammatory bowel disease (IBD)).

The hsCRP test is designed to measure chronic low-grade inflammation in the blood vessels. It is used to determine the risk of cardiovascular disease (CVD; i.e., the likelihood of heart disease or stroke) in an individual who appears to be healthy.

Can I buy a C-Reactive Protein Test online?

The Online Clinic can provide both High Sensitivity and Standard Sensitivity C-Reactive Protein tests.

Standard Sensitivity:

High Sensitivity:

How long do results take for C-Reactive Protein tests?

Results are available within 1 day of the sample arriving in the laboratory.

Why is a C-Reactive Protein test important?

Blood levels of CRP rise rapidly in response to an inflammatory stimulus. CRP levels decline quickly when the underlying inflammatory trigger resolves, either because the patient is healing on their own or the treatment is working. Long-term CRP elevation indicates ongoing inflammation from a continuing infection or a chronic inflammatory condition.

The standard CRP test is performed when a doctor wishes to:

• Confirm the presence of an infection or an acute or chronic inflammatory condition. CRP is a nonspecific marker of inflammation; it does not determine the cause or the source of the infection or inflammation.
• Monitor the progression of an infection or inflammatory condition (e.g., RA, SLE or IBD)
• Predict the likely course of a disease (e.g., an autoimmune disease, chronic kidney disease, CVD, and cancer) and identify potential complications
• Evaluate the body’s response to treatment and guide further treatment management of the condition.

The hsCRP test is performed when a doctor:

• Needs to assess the risk of CVD in a person who otherwise is seemingly healthy

Who should have their C-Reactive Protein level tested?

CRP should be evaluated in individuals with:

• Infection, injury, surgery, or flare-ups of autoimmune diseases
• A chronic active inflammatory condition (e.g., an autoimmune disease like RA and SLE)
• At high risk of cardiovascular disease

How to test for C-Reactive Protein?

A CRP test involves a blood test, where a small sample of your blood is taken either by a healthcare professional or yourself. A healthcare professional will take the sample using a small needle inserted into a vein in your arm. The test can also be sent to patients for self-collection of a blood sample from a little finger. The self-collection test kit is provided with instructions that must be carefully read and followed. In short, a lancet is used to puncture the little fingertip and blood drops are collected in the collection tube. Once blood has been collected up to the upper line on the collection tube (600 mcl), the tube is sealed and carefully inverted 5–10 times. Finally, the tube is labelled with the patient’s details, put in the packing wallet, and posted to the laboratory for analysis. Test results are sent to the doctor at The Online Clinic, who will interpret and explain the results.

What are normal C-Reactive Protein test results?

CRP levels vary between analysing laboratories. CRP levels indicate the degree of inflammation. As CRP is a nonspecific inflammatory indicator, the results should be interpreted alongside the clinical findings from other tests and investigations.

The standard test levels of CRP indicate:

• Below 0.3 mg/dL: Normal.
• 0.3–1.0 mg/dL: Normal/minor increase. Seen in: common cold, diabetes, obesity, depression, pregnancy, cigarette smoking, sedentary lifestyle, and genetic variances
• 1.0–10.0 mg/dL: Moderate elevation. Seen in: autoimmune diseases, heart attack, cancer, pancreatitis, and bronchitis
• Above 10.0 mg/dL: Marked elevation. Seen in: acute bacterial and infections, viral infections, and major trauma
• Above 50.0 mg/dL: Severe elevation. Seen in: acute bacterial infections

The hsCRP test levels of CRP indicate:

• Below 0.1 mg/dL: Low cardiovascular risk
• Between 0.1 and 0.3 mg/dL: Moderate cardiovascular risk
• Above 0.3 mg/dL: High cardiovascular risk

How to maintain normal C-Reactive Protein levels

If you have a high CRP level, your healthcare professional will consider all your clinical signs and symptoms and may arrange for further tests to determine the cause.

However, there are a few lifestyle modifications that may help to improve CRP levels, particularly if a chronic condition is suspected. These include: changes to diet to incorporate more anti-inflammatory foods (e.g., oily fish, leafy green vegetables, and turmeric) and less processed foods; regular physical exercise; reducing stress (e.g., by relaxation techniques or meditation); smoking cessation; and moderating alcohol intake.

References

MedlinePlus [Internet]. C-Reactive Protein (CRP) Test. National Library of Medicine (US) Updated Jun 11 2025. Available from: https://medlineplus.gov/lab-tests/c-reactive-protein-crp-test/

Rizo-Téllez SA, Sekheri M, Filep JG. C-reactive protein: a target for therapy to reduce inflammation. Front Immunol. 2023 Jul 26;14:1237729. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10410079/

Singh B, Goyal A, Patel BC. C-Reactive Protein: Clinical Relevance and Interpretation. 2025 May 3. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441843/