What is CRP (C-Reactive Protein)? CRP Elevation, Low Levels, and Normal Ranges

CRP

C-reactive protein (CRP) is the body's first response to inflammation. Produced in the liver, C-reactive protein can be an indicator of certain health problems. C-reactive protein has both anti-inflammatory and pro-inflammatory properties. It has two main primary functions. These can be explained as initiating the immune response and increasing phagocytosis. CRP can form complexes by binding to compounds such as fibronectin and phosphatidylcholine. The resulting complex structure activates the immune system. In the immune system, pro-inflammatory cytokines such as IL-1β, IL-6, and TNFa stimulate the liver to increase CRP release. In addition to the liver, it can also be produced in tissues such as the kidneys, heart, arteries, and adipocytes. This indicates that CRP can be an indicator of cardiovascular diseases along with being an inflammatory marker.

C-reactive protein does not indicate the location of inflammation in clinical diagnoses, but it can provide information about inflammation during the treatment process. Significantly high levels of CRP are often associated with infection. Rarely, trauma, as well as acute and chronic health problems, can also cause high levels. Milder elevations may be due to various factors such as gum disease, sleep disorders, etc. CRP values can double in approximately 8 hours. When inflammation ends, it returns to the liver to be catabolized. The half-life of CRP in the blood can reach 19 hours.

What is CRP?

C-reactive protein, known as CRP, is an acute-phase protein released from the liver in the presence of inflammation in the body. Injury or infection occurring in the body stimulates the immune system to initiate inflammation. Inflammation, which is a vital response, triggers an increase in blood flow to the area and allows the healing process to begin. The invasion and proliferation of pathogens such as bacteria, viruses, etc., in the infection area can threaten the immune system. To support the defense of the immune system, the production of C-reactive protein begins in the liver.

CRP produced in the liver can reach levels hundreds of times higher and is released into the blood. This initial response of the body to infection is called the acute-phase response.

The acute-phase response causes redness, pain, heat, and swelling in the infected area. However, the development of some autoimmune diseases and chronic health problems can also lead to CRP production. Therefore, CRP can be an important indicator in the diagnosis and follow-up of inflammatory diseases. CRP levels in plasma become detectable approximately 4 hours after injury or infection. It reaches peak levels 24 to 72 hours after injury or infection.

How is the CRP Test Performed?

The CRP test is determined by a blood sample taken from a vein. No preparation is required before giving blood. Fasting or other special procedures are not necessary. However, the medications the person is using and other treatment methods should be checked. A small amount of blood sample taken from the inner part of the arm is sent to the laboratory for testing. Possible complications of the blood collection procedure may include tenderness, redness, swelling, bruising, and rarely, infection. Routinely performed normal CRP tests are less sensitive measurements. Based on the type of health problem, a high-sensitivity CRP test (Hs-CRP) may be applied upon a doctor's recommendation. The high-sensitivity blood test is not used for differential diagnosis of CRP. Instead, it helps to detect much lower (0.3-1.0 mg/L) C-reactive protein values. Hs-CRP is specifically associated with the risk of health problems affecting the cardiovascular system, such as heart attacks. The high-sensitivity CRP test is not applied to everyone and does not show the exact cause of inflammation.

What is CRP Elevation?

CRP elevation does not always indicate inflammation or a serious illness. However, the underlying condition can be determined by considering different classifications of CRP elevation. Mild CRP elevation can often be a normal situation for conditions that do not require medical treatment. This situation can be considered normal for some lifestyle habits and certain changes occurring in the body. Additionally, some treatment options can also lead to this situation. The listed conditions are mainly:

Smoking,

Obesity (BMI>30 kg/m2),

High triglyceride levels,

Low HDL levels,

Blood pressure changes,

Diabetes,

Hormone replacement therapies,

Tissue damage,

Use of oral contraceptives can be among the causes of mild CRP elevation.

C-reactive protein levels that follow higher values may indicate some medical problems. CRP elevation, an acute-phase reactant, can be a result of the following conditions:

Viral and bacterial infections,

Burns and trauma,

Rheumatic diseases (Rheumatoid arthritis, Behçet's disease, osteoarthritis, etc.),

Inflammatory bowel diseases,

Autoimmune diseases,

Cardiovascular diseases,

Malignancies (cancer).

After the CRP elevation and its degree in the blood are well evaluated by your doctor, an appropriate treatment plan is created. CRP elevation can be seen during pregnancy, but it needs to be followed up during routine check-ups. CRP elevation in children can often be caused by viral or bacterial infections. CRP elevation in infants can be a marker for infection and genetic disorders.

What is Low CRP?

The normal CRP value is generally 50.0 mg/dL: Severe elevation (Acute bacterial infections)

CRP values can rise to mild levels by being affected by various factors. Smoking, obesity, diabetes, insomnia, pregnancy, common cold, depression, gingivitis, and old age are among these factors. High-sensitivity CRP measurements are generally used for cardiac risk assessment. The classification of Hs-CRP levels is as follows:

3 mg/dL: High cardiac risk.

Frequently Asked Questions

It can be risky when the CRP level is above the normal range. Therefore, values above 10 mg/dL can be dangerous and the underlying cause should be investigated. CRP elevation may not always indicate a dangerous situation, but in some people, it can be an indicator of serious medical problems. CRP, which is produced as an acute-phase reactant by the liver and released into the blood, can rise due to various reasons. CRP elevation may not always indicate a serious illness. Mildly elevated protein can manifest itself during pregnancy, insomnia, lack of physical activity, high BMI, and depression. Severely elevated CRP can often indicate bacterial infections. CRP elevation can be caused by various conditions such as inflammation in the body, injury and trauma, autoimmune and genetic disorders, cancer, diabetes and obesity, infections caused by viruses and bacteria, pancreatitis, bronchitis, depression, pregnancy, smoking, and the common cold. An increase in blood CRP may indicate inflammation that activates the immune system. This situation increases blood flow to the infected area and activates the immune system. A high CRP value may indicate the presence of pathogenic (disease-causing) microorganisms in the body. In children, the CRP blood test result should be lower than 10 mg/dL. C-reactive protein above 10 mg/dL can indicate acute inflammation in children. However, the underlying cause must be investigated with additional tests. The half-life of the amount of CRP in the body corresponds to approximately 19 hours. This duration is almost the same in healthy and unhealthy individuals. Performing repeated measurements instead of one-time measurements can provide more accurate results. When C-reactive protein is released at high values, the activity of acute bacterial infections in the body is considered. Bacteria are held responsible for approximately 90% of CRP cases >50 mg/dL. Therefore, antibiotics used in the treatment of bacterial infections can be effective in eliminating the infection and lowering CRP values. CRP elevation can be a harbinger of a wide range of health problems. Rheumatoid arthritis, Lupus (Butterfly disease), Behçet's disease, osteoarthritis, systemic lupus, MS, Psoriasis, inflammatory bowel disease, pancreatitis, heart attack, systemic vasculitis, cancer, bronchitis, diabetes, depression, etc., can be the cause of CRP elevation. Blood CRP values may be high in cancer patients. However, CRP may generally remain at normal values in leukemia cases. In addition, CRP may rise slightly due to tumor destruction in cancer treatments such as chemotherapy. Blood CRP values above 10 mg/dL may indicate tissue damage associated with cancer development. Levels of 50-100 mg/dL and above can indicate extensive tissue involvement and the progression of malignancy. CRP alone may not be sufficient for a cancer diagnosis. Therefore, the use of imaging methods is also recommended.

You can make an appointment with our specialist doctors to learn whether your CRP levels are in the normal range and to investigate the underlying cause. Click for an appointment.