Definition Anticoagulated blood is placed in a specially designed erythrocyte sedimentation rate tube and the distance that the erythrocytes settle over a certain period of time is observed and is called the Erythrocyte Sedimentation Rata (ESR), or hematocrit for short. There are several methods for determining sedimentation, and the WHO recommends the Westergren method. The principle of the test and the factors affecting it Anticoagulated blood is placed in a special tube for the sedimentation rate of red blood cells, which is vertically erected for 1h, and the rate of sinking of red blood cells is observed and expressed in terms of the height of the plasma segment (mm). Many factors affect ESR, the most important of which is the formation of erythrocyte coils. Because the total area of red blood cells decreases when they form coils or agglomerates, the plasma resistance is also reduced and the rate of descent is much faster than that of individual dispersed red blood cells. The main factors affecting the formation of coiled masses are: 1. The ratio of various proteins in plasma: It is generally believed that the acceleration of blood sedimentation is mainly due to the change in the ratio of various protein components in plasma, but not related to the total protein concentration. Albumin is negatively charged, globulin and fibrinogen is positively charged, under normal circumstances, the positive and negative charges of plasma proteins are in balance, and red blood cells are negatively charged due to the cell membrane surface of sialic acid, repelling each other spacing of about 25 nm. if the plasma content of fibrinogen or globulin increases or albumin content decreases, changing the balance of charges, resulting in a decrease in the negative charge on the surface of red blood cells, easy The red blood cells form a coiled money shape and the hematocrit is accelerated. On the contrary, if plasma fibrin fibrinogen is reduced or albumin is increased, hematocrit slows down. It is now recognized that fibrinogen, a positively charged asymmetric macromolecule in plasma, is the most potent substance that promotes coiled-coin aggregation, followed by gamma globulin, and then alpha and beta globulin. Cholesterol and triglycerides also have a role in promoting the formation of coiled blood cells, while albumin and lecithin have an inhibitory effect. 2, the number and shape of red blood cells: under normal circumstances, hematocrit and plasma reflux resistance to maintain a certain equilibrium, such as a decrease in the number of red blood cells, will cause a reduction in the total area, the plasma resistance to reverse also reduced, so the hematocrit accelerated. But the number is too small to affect the aggregation into a coin-like, so that the acceleration of sedimentation and the degree of red blood cell reduction is not proportional. Conversely, blood sedimentation slows down when red blood cells increase. The larger the diameter of red blood cells, the faster the sedimentation rate of red blood cells, spherical red blood cells are not easy to gather into a coin, blood sedimentation is slowed. 3, the position of the hematocrit tube: hematocrit tube tilt, red blood cells sink along one side of the tube wall, while the plasma rises along the other side, so that the hematocrit accelerated. Normal value Wei’s method: male 0~15mm/h; female 0~20mm/h Pan’s method: male 0~10mm/h; female 0~12mm/h Kirsch’s method: male 0~8mm/h; female 0~10mm/h Clinical significance of increased hematocrit ①Acute infection: such as acute bacterial inflammation, accelerated hematocrit will occur in 2~3 hours; ②Local inflammation; ③Active pulmonary tuberculosis, peritoneal tuberculosis ③ active pulmonary tuberculosis, peritoneal tuberculosis, renal tuberculosis, etc.; ④ active rheumatic immune diseases: such as rheumatoid arthritis, systemic lupus erythematosus, rheumatic fever, ankylosing spondylitis, gout, etc.; ⑤ myocardial infarction; ⑥ chronic nephritis; ⑦ severe anemia; ⑧ menstruation, pregnancy; ⑨ elderly; ⑩ malignant tumor. Clinical significance of slowed hematocrit: ① hypofibrinogenemia; ② true erythrocytosis; ③ spherocytosis; ④ allergic diseases; ⑤ low room temperature or prolonged storage after blood sampling. It should be noted that hematocrit is not a disease-specific indicator and its clinical significance is quite limited. The following points should be considered when applying hematocrit clinically: 1. A transient increase in sedimentation may be a harbinger of a hidden disease. Careful medical history and physical examination, combined with other ancillary tests such as immunology and CT of the lung, should be performed to clarify the cause of increased sedimentation; 3. 4. Blood sedimentation is only one of the diagnostic criteria for rheumatoid arthritis, ankylosing spondylitis and other rheumatic diseases, but it is not the only and necessary condition (high blood sedimentation does not necessarily mean rheumatic disease).