CRP Test (C-Reactive Protein)

• CRP test is done to assess presence of inflammation which results from infection, autoimmune diseases and injury which are common causes of unexplained fever, and joint pains.
• Serial measurements over days can provide useful information about the level & severity of the condition.
• The CRP test is performed to diagnose or monitor acute or chronic conditions that lead to inflammation in the body, such as rheumatoid arthritis, SLE, heart disease, IBS, sepsis, etc.

CRP test measures the level of C-reactive protein in blood.

CRP test requires a blood sample. A tourniquet (elastic) band is placed tightly on the upper arm. The patient is then asked to make a fist. This helps in the build-up of blood filling the veins. The skin is disinfected before needle insertion and the blood sample is collected in vacutainer. 

• A high CRP levels are a non-specific indicator of inflammation & injury. Results should be interpreted in light of clinical history of the patient and results of other biomarkers. 
• A low CRP result, despite inflammation, can occur in patients with liver disease.
• A moderately high CRP test could be due to the following conditions - SLE, heart attack, inflammation of the pancreas, or inflammation of the lung.
• A marked high CRP test is associated with acute bacterial infection, viral infection, systemic inflammation of the blood vessels, or trauma.
• A severely high CRP test is majorly associated with acute bacterial infection.

After having a high CRP test, you may go for a retest post-treatment to monitor your CRP levels. A decreasing value means that the treatment is working for you.

• High-sensitivity CRP levels of less than 2 mg/L mean a lower risk of heart disease.
• High-sensitivity CRP levels of more than or equal to 2 mg/L mean a higher risk of heart disease.

There is no preparation required for the CRP test. However, you may refer to your healthcare provider or laboratory for any recommendations.

CRP is usually measured in mg/L. Some laboratories measure it in mg/dL. The values are as given below:

• Normal: Less than 0.9 mg/dL
• High: 0.3 to 1.0 mg/dL
• Moderately high: 1 to 10 mg/dL
• Severely high: More than 50 mg/dL

The following factors affect a CRP test -

• Obesity
• Depression
• Lack of sleep
• Pregnancy
• Estrogen-based medications like birth control pills
• Chronic conditions like autoimmune diseases
• Common cold
• Smoking
• Gingivitis
• Recent injury
• Diabetes

Other tests that can be prescribed along with the CRP test depend upon the condition for which a CRP test has been recommended by your doctor. For example, a hs-CRP test (high-sensitivity C-reactive Protein test) may be prescribed for diagnosing the risk of heart disease. Consult your doctor for more information.

• C-reactive Protein Test
• CRP Blood Test

Your doctor may advise you to go for a CRP test if you have the following symptoms:

• Fever with chills
• Rapid breathing
• Rapid heart rate
• Nausea
• Vomiting
• Unexplained exhaustion
• Pain
• Headache
• Difficulty in sleeping
• Unexplained weight loss
• Indigestion
• Loss of appetite
• Muscular stiffness
• Muscular soreness and weakness

CRP test is usually done to diagnose or rule out certain conditions. People who have symptoms of the following conditions should go for a CRP test:

• Fungal infection
• Inflammatory Bowel Disease (IBS)
• Sepsis
• Arthritis
• Heart disease
• Risk of second heart attack
• Rheumatic fever
• SLE (Systemic lupus erythematosus)
• Rheumatoid Arthritis
• Pelvis Inflammatory Disease
• Cancer
• Organ or tissue injury
• Inflammation of the lining of the heart (Pericarditis)
• Osteomyelitis