What are the normal values and clinical significance of CRP?

CRP usually refers to C-reactive protein. Under normal circumstances, the normal reference range for C-reactive protein is 0-10mg/L. This is an acute-phase protein synthesized by the liver, whose levels rise during bodily inflammation, infection, tissue damage, or certain disease states. Detailed analysis is as follows:

I. Normal Range

The normal reference range for C-reactive protein is generally 0-10mg/L. In healthy individuals, C-reactive protein levels are typically maintained at low levels, even approaching 0mg/L. This is because when the body isn't subjected to significant stimuli such as inflammation, infection, or tissue damage, the mechanism for hepatic synthesis of C-reactive protein remains relatively suppressed. For example, in routine health checkups, healthy adults usually have C-reactive protein levels below 5mg/L; children and adolescents have a normal range similar to adults and generally do not show elevated levels.

II. Clinical Significance

The clinical significance of C-reactive protein mainly lies in its role as a sensitive marker of inflammation and infection. When the body experiences bacterial infection, C-reactive protein levels rapidly increase within hours, peaking at 24-48 hours, with the degree of elevation correlating with the severity of the infection. For example, in patients with bacterial infections such as pneumonia or pyelonephritis, C-reactive protein levels often rise above 50mg/L, even exceeding 100mg/L. In contrast, during viral infections, C-reactive protein levels typically do not increase significantly or only show mild elevation, a characteristic that can help distinguish between bacterial and viral infections. Additionally, in cases of tissue damage such as myocardial infarction and surgical trauma, CRP levels also rise. In myocardial infarction patients, CRP begins to increase 12-24 hours after onset, reaching a peak at 48-72 hours, then gradually declines, which can be used to assess disease progression and prognosis. In autoimmune diseases such as rheumatoid arthritis, elevation of C-reactive protein levels closely correlates with inflammatory activity and can serve as an indicator for monitoring treatment response and disease activity. Furthermore, chronic inflammatory conditions such as obesity and diabetes may also show mild elevations in CRP, suggesting that chronic low-grade inflammation is associated with the development of these diseases.

When test results are abnormal, timely consultation with a physician is advised to avoid self-diagnosis or indiscriminate medication use. Also, normal levels do not completely rule out disease, as in some early inflammatory conditions or localized mild infections, C-reactive protein may not yet be significantly elevated, requiring further clinical evaluation.