Inflammatory markers are substances in the blood that change in concentration in response to inflammation within the body. These markers are typically measured through blood tests and provide an indication of the body’s inflammatory state. They serve as objective measurements that clinicians use to gain insight into a person’s internal biological processes.
What Inflammatory Markers Indicate
Inflammatory markers signal the body’s protective response to various stimuli, such as infection, injury, or harmful irritants. Elevated markers mean the immune system has activated to address a perceived threat or damage. While these markers confirm the presence of inflammation, they do not pinpoint the specific cause or exact location of the inflammation.
These markers can be useful in diagnosing or monitoring various conditions, including infections, autoimmune diseases, and certain cancers. They can also help distinguish between different types of conditions, such as inflammatory bowel disease versus irritable bowel syndrome. For individuals already diagnosed with an inflammatory disease, changes in marker levels can indicate a flare-up or how well a treatment is working.
Common Inflammatory Markers and Their Roles
C-reactive protein (CRP)
C-reactive protein (CRP) is a widely measured inflammatory marker, produced by the liver in response to inflammation. Its levels can rise rapidly after injury or inflammation onset. CRP helps activate the complement system, which helps clear dead cells and pathogens. It is used to detect acute inflammation and monitor disease activity; normal values are generally below 3 mg/L, but can exceed 100 mg/L in inflammatory conditions.
Erythrocyte Sedimentation Rate (ESR)
Erythrocyte Sedimentation Rate (ESR), also known as “sed rate,” measures how quickly red blood cells settle in a test tube. During inflammation, proteins in the blood can cause red blood cells to clump, making them heavier and sink faster. A faster sedimentation rate indicates higher levels of inflammation. While ESR is a general indicator, it can be influenced by factors like age, gender, smoking, and anemia.
Fibrinogen
Fibrinogen, a protein produced in the liver, is primarily known for its role in blood clotting. However, it also functions as an acute-phase reactant, with levels increasing significantly in response to tissue inflammation and necrosis. Elevated fibrinogen levels are associated with various inflammatory conditions, including cardiovascular disease, peripheral artery disease, stroke, and active inflammatory bowel disease. Fibrinogen and its conversion into fibrin can also directly influence immune cell activity and promote local inflammation.
Ferritin
Ferritin, primarily an iron storage protein, also acts as an acute-phase reactant and inflammatory marker. Its levels can increase during infections and other inflammatory conditions, even with normal or low iron stores. While ferritin reflects iron status, its elevation in inflammatory states can mask an underlying iron deficiency, making comprehensive iron profile testing important. Ferritin levels have been linked to various inflammatory pathologies, including autoimmune diseases and certain cancers.
Factors That Influence Inflammatory Marker Levels
Inflammatory marker levels can be influenced by factors beyond inflammation. Age can affect marker levels, with older individuals often having higher ESR values. Obesity can elevate markers due to low-grade, chronic inflammation. Lifestyle choices, including diets rich in processed foods, chronic stress, and sleep disorders, can also increase markers.
Certain medical conditions can also impact inflammatory marker levels. Acute infections, whether bacterial or viral, cause a rapid increase in markers like CRP. Chronic inflammatory diseases, such as rheumatoid arthritis, systemic lupus erythematosus (SLE), and inflammatory bowel disease, consistently elevate levels. Injuries, trauma, and certain cancers can also raise these markers. Additionally, some medications, like steroids, or hormonal changes, such as those during pregnancy, can influence test results.
Interpreting Inflammatory Marker Test Results
Interpreting these results requires a healthcare professional. They consider the complete clinical picture, including the patient’s symptoms, medical history, and findings from other diagnostic tests.
Elevated levels do not automatically signify a serious condition; a mild viral infection can cause a temporary rise. Conversely, normal marker levels do not always rule out an underlying health problem, especially in early disease stages. If the cause of an elevated marker is not immediately apparent, a doctor might repeat the test or recommend further investigations to determine the inflammation’s root cause.