High hematocrit is not harmful. In clinical practice, increased hematocrit does not have a certain specific diagnostic value. However, various diseases can cause a high hematocrit, so an increased hematocrit must depend on the specific disease, i.e., the harm to the body from the primary disease. For example, various inflammatory diseases can lead to increased hematocrit, such as inflammatory lesions caused by various bacteria, viruses, chlamydia, mycoplasma, fungal infections, etc., which can cause a significant increase in hematocrit. In addition, there are some non-suppurative inflammatory diseases, such as autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and various vasculitis, etc., which can lead to an increase in hematocrit and, of course, can be life-threatening. In addition, there are some tumor diseases that can also lead to increased blood sedimentation, such as lung cancer, stomach cancer, lymphoma, leukemia, etc. Therefore, it is important to clarify the original disease, that is, to see what disease is causing the increased blood sedimentation, and then determine the danger.