Blood concentration, also known as the viscosity of blood, is an indicator of blood fluidity. Normal adult male blood viscosity is 3.84-5.30, adult female blood viscosity is 3.39-4.41, blood viscosity higher than the normal range is blood viscosity increased, common diseases are various diseases caused by the increase in the number of blood cells, such as primary thrombocytosis, true erythrocytosis, blood viscosity will be significantly higher, in addition, coronary heart disease, myocardial infarction, hypertension diabetes mellitus, hyperlipidemia, pulmonary heart disease, and multiple myeloma, blood viscosity will also appear significantly higher. Decreased blood viscosity is commonly seen in severe anemia, severe fibrinogen deficiency, and other coagulation factor deficiencies where there is a significant local decrease in blood viscosity.