A month ago, he began to experience dizziness and swelling, with occasional headaches and purple hands. The doctor found that the red blood cells and hemoglobin were elevated and that the blood viscosity was increased. The doctor highly suspected that Mr. Wang was suffering from true erythrocytosis and recommended that he be hospitalized. Polycythemic Vera (PV) is a clonal disorder of hematopoietic stem cells of unknown origin, which belongs to the category of myeloproliferative disorders. It is characterized clinically by a significant increase in the number and volume of red blood cells and is often accompanied by an increase in myelocytes and platelets. The current population prevalence of true red is 1.9-2.6 per 100,000, with a prevalence in middle-aged and elderly people. What are the manifestations of Erythroblastosis? True erythrocytosis starts insidiously, progresses slowly, and often goes undetected. Patients are occasionally detected by routine blood tests, and commonly present with a reddish-purple color on the face, palms, lips, etc., dilated and congested conjunctival vessels, splenomegaly, and hypertension are also more common. Some patients may directly present with thrombosis (due to increased blood viscosity caused by excessive red blood cell proliferation, resulting in slow blood flow and thus vascular embolism) or bleeding symptoms (due to vasodilation, vascular endothelial damage and abnormal platelet function), such as nosebleeds, gum bleeds or petechiae or petechiae on the skin mucosa, or some patients may present with vascular nervous system symptoms, such as dizziness, headache, limb numbness, tinnitus, blurred vision, amnesia, etc. How is true erythrocytosis diagnosed? In addition to the typical symptoms and signs mentioned above, the diagnosis of true erythrocytosis also relies on laboratory tests. Routine blood tests show increased red blood cell count, mostly in the range of (6-10) × 1012/L, hemoglobin in the range of 165-240 g/L, and hematocrit of 48%-80%. The red blood cell morphology was normal, with occasional mild size variation and occasional infantile red blood cells. The white blood cell count and platelet count are mostly elevated, with half of the patients having a white blood cell count of (10.0-30.0)×109/L and half of the patients having a platelet count of (450-1000)×109/L. The bone marrow examination shows that the red lineage, granulocytes and megakaryocytes are actively or significantly proliferating, especially the young red blood cells. Blood viscosity is increased and JAK2v617F gene mutation can be detected in most patients. Currently, hematocrit >52%, JAK2v617F mutation, endogenous erythroid colony formation, and reduced plasma erythropoietin (EPO) levels are the more specific diagnostic criteria for early and morbid stages of true redness. It is also necessary to exclude external secondary erythrocytosis, especially due to cardiopulmonary insufficiency, renal, hepatic, cerebellar and gynecologic tumors. How to treat true erythrocytosis? The treatment of true erythrocytosis should be different depending on the amount of hemoglobin in the patient and the presence of hyperviscosity syndrome. If the presence of hyperviscosity syndrome live hemoglobin is higher than 200g/L, intravenous bloodletting should be done once every 1-3 days, 200-400ml each time, with caution in elderly patients or patients with cardiovascular disease. The hemoglobin can also be reduced more quickly by using a hemocyte separator to remove the red blood cells. Myelosuppressive therapy is required after bleeding or erythrocyte debridement. Myelosuppressive drugs include hydroxyurea, hypertrigonelline, and also alpha-interferon for myelosuppression. Hydroxyurea, a ribonucleic acid reductase, has a good inhibitory effect on true erythrocytosis at a daily dose of 15-20 mg/kg. hydroxyurea should be given as a maintenance dose after hemoglobin and hematocrit are at normal levels, and the dose varies among individuals and should be individualized for maintenance therapy. Interferon has an inhibitory effect on cell proliferation and can be given as 300 U daily or every other day subcutaneously. Attention should be paid to the side effects of interferon, which can be treated with antipyretic and analgesic drugs as appropriate. The doctor reminded Mr. Wang that he still needs to continue his medication after he is discharged from the hospital to maintain his treatment and to be reviewed regularly. Because true erythrocytosis is a benign disease, but a very small number of patients will transform into myelofibrosis or leukemia, it is important to pay full attention and monitor the condition regularly.