C-reactive protein 300mg/L is more serious, indicating the presence of inflammatory infection or tissue damage. C-reactive protein is a diagnostic indicator with a normal value of <10mg/L. C-reactive protein is an important acute time-phase reactive protein in humans, and it can be correspondingly elevated after the occurrence of a variety of acute inflammation, tissue injury, myocardial infarction, surgical trauma, and radiological injury, among other diseases. If C-reactive protein has reached 300mg/L, it indicates that these types of injuries or inflammation may be present. Once C-reactive protein is found to be 300mg/L, you should promptly cooperate with your physician to do the corresponding diagnostic examination, clarify the cause of the disease, and actively carry out treatment under the guidance of your physician, so that the C-reactive protein can be restored to the normal range.