What is the normal value for C-reactive protein?

C-reactive protein (CRP) is a plasma protein that exhibits a rapid and marked increase in concentration during infection or tissue injury.

What Is the Normal Range for C-Reactive Protein?

The term “reactive protein” commonly refers to C-reactive protein (CRP), an acute-phase protein synthesized by hepatocytes. Its plasma concentration rises sharply in response to infection or tissue injury. In healthy individuals, baseline CRP levels are very low. The standard reference range used by most clinical laboratories is 0–5 mg/L.

CRP is synthesized primarily by hepatocytes. Upon microbial invasion or tissue damage, hepatocytes significantly upregulate CRP synthesis and secretion into the bloodstream. Serum CRP levels typically begin to rise within 6–8 hours after the onset of acute infection, with the magnitude of elevation correlating closely with disease severity.

Elevated CRP levels are commonly observed in various acute inflammatory conditions, tissue injuries, myocardial infarction, radiation-induced damage, and postoperative states. CRP contributes to host defense by activating the complement system and enhancing phagocytosis by macrophages and neutrophils—thereby facilitating clearance of invading pathogens as well as damaged, necrotic, or apoptotic cells. Clinically, CRP measurement is frequently employed to help differentiate bacterial from viral infections, since CRP levels usually remain normal or show only minimal elevation in most viral infections. Following resolution of infection or inflammation, CRP levels decline rapidly and return to baseline.

The above provides an overview of the normal reference range for C-reactive protein. We hope this information is helpful to you.