C-reactive protein (CRP): Types, Procedure and Normal Ranges

The C-reactive protein (CRP) test is an important diagnostic tool in modern medicine, frequently used to evaluate inflammation levels in the body. Research indicates that elevated CRP levels are found in more than 60% of patients with chronic inflammatory diseases, highlighting its significance for early diagnosis and treatment. This test is crucial for identifying infections, chronic inflammatory diseases, and various other medical conditions. In this article, we explore the details of the CRP test, addressing common questions and offering practical insights into its purpose, procedure, and importance.

What is the C-Reactive Protein (CRP) Test?

C-reactive protein (CRP) is a glycoprotein made by the liver, and it is typically not found in the blood. When there is acute inflammation and tissue damage in the body, its production is triggered. Consequently, a positive CRP result indicates that an inflammatory process is occurring. Once the acute inflammation subsides, CRP levels quickly decrease. CRP levels usually rise within 6 hours of the onset of inflammation, making it possible to confirm inflammation much earlier than the erythrocyte sedimentation rate (ESR), which typically takes about a week to show an increase after inflammation begins.

Types of C-Reactive Protein (CRP)

1. Standard CRP

The standard CRP is used to evaluate the activity of inflammation in chronic conditions like inflammatory bowel disease, arthritis, and autoimmune disorders; to check for new infections such as appendicitis and in postoperative situations; and to monitor how well these conditions are responding to treatment.

2. High-Sensitivity CRP (hs-CRP),

High-sensitivity CRP (hs-CRP), which serves as a marker for low-grade vascular inflammation, a significant factor in the formation and rupture of atheromatous plaque. High levels of CRP can indicate an increased risk of future coronary events, stroke, peripheral vascular disease, and type 2 diabetes mellitus. Therefore, this test is often used to evaluate cardiovascular risk alongside other tests, such as cholesterol level measurements.

The Evidence for CRP Practices

When addressing issues like rheumatoid arthritis, skin infections, and pelvic inflammatory disease, laboratory tests often include acute phase reactants (APRs), the erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). These APRs serve as reliable indicators of the inflammatory activity associated with these conditions.

Measuring serum CRP levels can be useful in deciding whether to use antibiotics for patients with cerebrospinal fluid (CSF) findings that suggest meningitis, especially when the Gram stain result is negative. This guidance is supported by data indicating that a normal CRP level has a high negative predictive value for diagnosing bacterial meningitis.

Ongoing research is exploring the role of high-sensitivity CRP (hs-CRP) in predicting cardiovascular risk, particularly among women and individuals with metabolic syndrome, as well as its potential in assessing the risk of colon cancer and monitoring lung lesion progression.

Why is a CRP Test Ordered?

Diagnosing Infections and Inflammatory Conditions A CRP test is commonly ordered to assist in diagnosing infections or inflammatory conditions.
Bacterial vs. Viral Infections: CRP Differences CRP levels can help distinguish between bacterial and viral infections, with bacterial infections typically causing a more significant increase in CRP.
Autoimmune Diseases and CRP Levels Conditions such as rheumatoid arthritis or lupus often result in elevated CRP levels due to persistent inflammation.
Monitoring Treatment Effectiveness This test aids doctors in assessing how effective treatments are.
Assessing Cardiovascular Risk CRP is also utilized to evaluate the risk of heart disease, with higher levels potentially indicating an increased likelihood of heart problems.
Post-Surgical Monitoring Following surgery, CRP levels can be useful in tracking recovery and spotting possible complications.

How is the CRP Test Performed?

Pretest
- Explain to the patient the purpose of the test and the need for a blood sample to be drawn.
- Laboratories may vary in preparation for the test: some require no preparation while others require fasting for 4 to 12 hours before the test. Water is allowed.
Procedure
- A 5-mL blood sample is drawn in a green-top collection tube
- Gloves are worn throughout the procedure
Posttest
Apply pressure at venipuncture site, periodically assessing for continued bleeding, apply dressing.
Label specimen and transport to the laboratory immediately.
Report abnormal findings to the primary care provider.

Interpretation of CRP Test Results

what are the normal ranges of C-Reactive Protein (CRP)?

Normal Values CRP
- 0–1.0 mg/dL
- <10 mg/L (SI units)
hs-CRP (assessing risk of CV disease):
- <1.0 mg/L = Lowest risk
- 1.0–3.0 mg/L = Average risk
- 3.0 mg/L = Highest risk

Possible meanings of CRP abnormal values

The patient with high hs-CRP levels should receive guidance on strategies to lower their risk of cardiovascular disease and may need further diagnostic tests to assess for early signs of cardiovascular issues.
Additionally, elevated CRP levels should be evaluated alongside other diagnostic results, like an increased white blood cell count, to help identify the potential causes of the abnormal finding.

Increased CRP	Increased hs-CRP
Acute pancreatitis Appendicitis Bacterial infection Burns Increased risk of colon cancer development Inflammatory bowel disease Lupus Lymphoma Myocardial infarction Pelvic inflammatory disease Polymyalgia rheumatica Rheumatoid arthritis Sepsis Surgery (first 3 post-op days) Tuberculosis	Increased risk of cardiovascular disease

Contributing Factors to Abnormal Values

False-negative: medications such as nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin, corticosteroids, statins, and beta blockers
False-positive: medications like hormone replacement therapy and oral contraceptives
Use of an intrauterine device (IUD)
Engaging in vigorous exercise
Being pregnant
Having obesity

How Much CRP Level Is Dangerous?

CRP levels can vary significantly based on the underlying condition that is causing inflammation. Typically, a CRP level below 0.3 mg/dL is considered normal. Levels ranging from 0.3 to 1.0 mg/dL suggest mild to moderate inflammation, while levels exceeding 10.0 mg/dL indicate severe inflammation.

It’s crucial to understand that a high CRP level doesn’t always point to a serious health issue. For instance, elevated CRP levels can occur due to minor infections or injuries. On the other hand, a normal CRP level does not completely rule out the presence of an underlying condition.

Normal

A CRP level of less than 0.3 mg/dL is regarded as the normal range for an individual.

Mild Elevation

A CRP test result between 0.3 and 1.0 mg/dL is considered normal or shows a minor elevation. This could be due to several factors, including:

Pregnancy
Depression
Diabetes
Cold
Obesity
Sedentary lifestyle
Smoking

Moderate Elevation

A CRP result between 1.0 and 10.0 mg/dL is generally seen as moderately elevated. This could indicate any of the following conditions:

Systemic inflammation from autoimmune diseases like systemic lupus erythematosus (SLE) or rheumatoid arthritis.
Heart attack (myocardial infarction).
Pancreatitis
Bronchitis

Marked Elevation

A CRP level above 10.0 mg/dL is usually classified as marked elevation. This could be associated with:

Acute bacterial infections
Viral infections
Systemic vasculitis
Major trauma or injury

Severe Elevation

A CRP level exceeding 50.0 mg/dL is typically considered serious. In fact, about 90% of cases with levels higher than 50.0 mg/L are linked to acute bacterial infections.

CRP Semi Quantitative Rapid Test Method

Lowering Your CRP Levels Naturally

Lifestyle Modifications:

Diet, Exercise, and Weight Management
- Making adjustments to your lifestyle can effectively help lower CRP levels.
Diet Recommendations for Lowering CRP: Anti-inflammatory Foods Include foods such as:
- Fatty fish (high in omega-3s)
- Leafy greens (like spinach and kale)
- Nuts and seeds
Impact of Regular Exercise on CRP Reduction
- Regular physical activity can help reduce inflammation and lower CRP levels. Aim for at least 150 minutes of moderate exercise each week.
Stress Reduction Techniques and Their Impact on Inflammation
- Managing stress is essential for lowering CRP. Techniques like meditation and yoga can be particularly beneficial.
Meditation, Yoga, and Mindfulness Practices
- These practices encourage relaxation and can contribute to lower CRP levels over time.

Conclusion: Taking Control of Your Health

Key Takeaways: CRP Testing and its Implications

C-Reactive Protein testing provides important insights into your health. Knowing your CRP levels allows you to take charge of your well-being.
When to Consult a Healthcare Professional
If your CRP levels are elevated or if you have ongoing health issues, it’s wise to consult a healthcare provider. They can help you understand your results and suggest appropriate next steps.

Proactive Health Measures for Reducing Inflammation

Adopt healthy lifestyle choices, manage stress, and stay active to lower your CRP levels and improve your overall health. Taking these actions can lead to significant enhancements in your well-being.

User Queries

What tests should I take for fatigue?

Fatigue can stem from a variety of conditions. Commonly recommended tests include a complete blood count (CBC), thyroid function tests, CRP, and iron studies. Depending on your symptoms, additional tests such as vitamin D and B12 levels, along with liver and kidney function tests, may also be necessary. Tests like the CBC, thyroid function tests, and CRP can help pinpoint underlying issues.

Can CRP tests detect early signs of disease?

Yes, CRP test can identify inflammation at an early stage, which is crucial for timely diagnosis and management of potential health issues.

How accurate are CRP laboratory test results?

Pathology tests, including the CRP test, are very accurate when performed in certified laboratories. However, it’s important for healthcare professionals to interpret the results.

What is an alarming level of CRP?