Laboratory Markers of Inflammation: CRP and ESR in Clinical Practice

Abstract

C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are two widely used laboratory markers for detecting inflammation in clinical practice. CRP is an acute-phase reactant produced by the liver in response to inflammatory cytokines, particularly interleukin-6 (IL-6). It rises quickly within hours of an inflammatory stimulus, making it a sensitive marker for acute inflammation, infection, and tissue injury. Elevated CRP levels can indicate various conditions, such as systemic infections, autoimmune diseases, and inflammatory disorders, guiding clinicians in diagnosing and monitoring responses to treatment. It is particularly valuable due to its rapid response to changes in the inflammatory state, providing real-time insights into a patient's condition. In contrast, the erythrocyte sedimentation rate (ESR) reflects the rate at which red blood cells settle in a vertical column of blood and is influenced by the presence of acute-phase proteins like fibrinogen that increase during inflammation. Although ESR is a useful marker for chronic inflammation, its slower response time—often taking hours to days to elevate—limits its utility in acute settings. ESF can be influenced by several factors, including age, gender, and the presence of anemia. Despite these limitations, both CRP and ESR are valuable tools in clinical practice when interpreted together with clinical findings and other diagnostic tests, enhancing the understanding of a patient’s inflammatory status.