The causes of high percentage of nucleated red blood cells mainly include: anemia, malignant diseases of hematopoietic system, chronic myeloproliferative diseases, etc. 1. Anemia: severe hemolytic anemia, autoimmune hemolytic anemia, megaloblastic anemia, due to massive destruction of erythrocytes, hypoxia, increased erythropoietin level, myeloproliferative erythropoiesis, reticulocytes and part of the naïve erythrocytes are released into the blood ahead of time, which need to be treated for the cause of the disease, such as being treated with prednisone for immune hemolysis. 2. Malignant diseases of hematopoietic system: all kinds of acute and chronic leukemia, due to the bone marrow filled with a large number of leukemia cells, so that the early release of young red blood cells, can be seen in the middle and late young red blood cells, or even earlier stage of naïve red blood cells, accompanied by cell morphology abnormality, the need to use chemotherapeutic drugs, including cytarabine, erythromycin, and so on. 3. Chronic myeloproliferative diseases: such as myelofibrosis, blood smear can be seen nucleated erythrocytes, mostly from extramedullary hematopoiesis and fibrotic bone marrow, generally need to use hydroxyurea and other drugs for treatment. Nucleated erythrocytes generally only exist in the bone marrow, adult peripheral blood does not contain nucleated erythrocytes, if the patient found in the peripheral blood with an increased proportion of nucleated erythrocytes, it is recommended to actively improve the cause of further examination, under the guidance of a physician to receive treatment.