Blood sedimentation is the rate at which red blood cells settle under certain conditions, referred to as hematocrit. In healthy individuals, the value of hematocrit fluctuates within a narrow range, while in many pathological conditions it increases significantly. Erythrocyte sedimentation is the result of the interaction of several factors. Physiological increases can occur in women during menstruation and in advanced age over 60 years; pathological increases can occur in various inflammatory conditions, hyperglobulinemia, malignancy, tissue damage and necrosis, anemia, and hypercholesterolemia. Which diseases will have accelerated blood sedimentation and need to be alerted? Rheumatoid immune diseases such as rheumatoid arthritis, ankylosing spondylitis, lupus erythematosus, and scleroderma are the most common. Other acute bacterial inflammatory diseases such as cold and pneumonia, tuberculosis; acute myocardial infarction and other tissue damage and necrosis (note that the blood sedimentation does not change much in angina pectoris), the blood sedimentation will increase significantly; malignant tumors; chronic nephritis and other kidney diseases blood sedimentation will also increase. It is important to note that an increased sedimentation rate does not necessarily mean that the person is ill. For example, children under 12 years of age, elderly people over 60 years of age, and women who are menstruating or more than 3 months pregnant can often have an increased sedimentation rate, which should be considered in conjunction with other conditions. C-reactive protein is an acute phase protein with the same clinical significance as hematocrit, but is not affected by factors such as red blood cells, lipids and age, and is a good indicator of response to inflammatory infection and healing. Blood sedimentation and C-reactive protein increase when there is inflammation and other conditions, and they are correlated with disease activity; these two indicators are often tested clinically to help clinicians determine the condition. However, it must be noted that patients should not rely excessively and singularly on these two indicators to judge the disease, because there are many factors affecting these two indicators, and clinicians must also judge the disease based on clinical symptoms, laboratory tests, imaging data, etc. CRP test is widely used in the diagnosis and treatment of rheumatic immune diseases, such as rheumatoid arthritis, ankylosing spondylitis and systemic lupus erythematosus, etc. CRP is often significantly elevated during the active phase of connective tissue diseases. When the disease is effectively controlled or the inflammation is eliminated, the CRP value decreases accordingly, and many patients can drop to within the normal range. Of course, if a CRP value that has fallen to normal rises again during the recovery process of inflammation, it often indicates that the disease is active again. If the CRP value increases during the course of treatment compared to the previous one, it indicates that the disease is still active and the inflammation is aggravated, which requires an overall assessment and timely adjustment of the medication.