1, Overview: C-reactive protein (C-reactive protein, CRP) was discovered by Tillet and Francis in 1930 in the serum of some patients with acute diseases, is a cyclic pentaglobulin, belongs to Oligomeric calcium binding protein, is an inflammatory lymphokine interleukin-6, interleukin-1, tumor necrosis factor stimulated liver epithelial cells synthesized. It is named because of its ability to precipitate with the podococcal C polysaccharide of Streptococcus pneumoniae. Hyper-sensitivity C-reactive protein (highsensitivity C-reactive protein, hs-CRP) is used as a highly sensitive assay, i.e., the assay has the ability to detect CRP at ≤0.3 mg/L. 2, clinical application: elevated during microbial invasion, tissue damage, immune response, inflammatory process, appears quickly, short half-life, changes with the inflammatory process, the level of CRP is correlated with the appearance of inflammation and its severity. However, CRP cannot pass through the placenta, so the level in the serum of normal newborns is extremely small. Diagnosis and differentiation of infection: Since CRP starts to rise 6-8h after the onset of infection and reaches a peak in 24-48h, the peak value can be hundreds of times higher than normal, and its level drops sharply after the infection is eliminated and can return to normal within a week. In contrast, CRP is not significantly elevated in viral infections, which provides an extremely important basis for identifying the type of infection in the early stages of the disease. Determining the efficacy of antibiotics: CRP also plays a role in determining the efficacy of antibiotics. A Norwegian research group treated 11 confirmed cases of pharyngitis infected with Streptococcus haemolyticus type A with antibiotics and also recorded their CRP levels, body temperature and reduction in sore throat before and 1, 2 and 3 d after treatment. The results showed that CRP decreased by 34.1%, 60.1% and 75.3% at 1, 2 and 3 days after treatment, respectively, compared with that before treatment, and the degree of CRP reduction was significantly correlated with the reduction of symptoms and the number of days after treatment (P<0.01). Association with cardiovascular disease: hs-CRP is a predictor of future morbidity and mortality from cardiovascular disease. Secondly it is also a good prognostic indicator. Atherosclerotic injury, the degree and extent of local inflammation causing an irritant response can lead to elevated serum hs-CRP levels, and increased CRP is seen in patients with acute localized myocardial ischemia and subsequent myocardial infarction, with a peak at 36-96 h after symptom onset. CRP >15 mg/L is a strong 90-day deterioration in patients with unstable angina predictor. The European Angina Collaborative Group reported that CRP concentrations were found to be directly associated with the development of coronary lesions in angina after a 2-year follow-up.