Role of C-reactive protein in disease progression, diagnosis and management

C-reactive protein (CRP) is a ring-shaped pentameric protein synthesized in the liver via CRP gene transcription. It is an inflammatory marker, whose serum levels can be measured using traditional and high-sensitivity tests. In healthy adults, the normal CRP serum concentrations vary between 0.8 mg/L and 3.0 mg/L. These can be grouped into low-, moderate-, and high-risk categories according to CRP levels of less than 1, 1-3, and greater than 3 mg/L, respectively. Elevated levels have been observed in infections, autoimmune diseases, neurodegenerative disorders, and malignancies. However, it is not specific to any disease. Serum CRP levels have also been shown to indicate the risk of cardiovascular disease, owing to their role as inflammatory markers in atherosclerosis, coronary artery disease, and peripheral arterial disease. Furthermore, its role in autoimmune diseases, such as Systemic Lupus Erythematosus and rheumatoid arthritis, and its involvement in the development of cancers, including breast, colorectal, ovarian, prostate, and lung cancers, have also been studied. The involvement of CRP in determining the course of infection and differentiating between bacterial and viral infections has also been investigated. This review summarizes the published literature on C-reactive protein and its role in disease management and progression.