Pancytopenia is commonly associated with hematopoietic disorders, but non-hematopoietic disorders such as infections, liver diseases, and immune system diseases may also cause Pancytopenia. 1. Hematopoietic system diseases (1) Aplastic anemia: it is the most important cause of pancytopenia. (2) Myelodysplastic syndrome: abnormal bone marrow hematopoiesis, manifested as pathological hematopoiesis and ineffective hematopoiesis, may lead to PBC. (3) Acute leukemia: a malignant clonal disease of hematopoietic stem cells, in which abnormal primitive and naïve cells in the bone marrow proliferate, affecting the normal differentiation of hematopoietic stem cells. (4) Anemia: such as megaloblastic anemia, when the condition is serious, it can also be manifested as a decrease in the number of whole blood cells. (5) Primary immune thrombocytopenic purpura: immune-mediated thrombocytopenic disease, severe bleeding can cause pancytopenia. (2) Infectious diseases: such as typhoid fever, tuberculosis, sepsis, etc. Pathogenic microorganisms release toxins throughout the body and inhibit hematopoietic function, which may result in pancytopenia. 3. Acute and chronic liver diseases: such as liver inflammation, liver fibrosis, liver cirrhosis, etc. 4. Autoimmune diseases: such as systemic lupus erythematosus, rheumatoid arthritis and so on. Patients with PBC are often accompanied by other diseases, so once you notice symptoms such as frequent skin bruises, frequent nosebleeds, pale skin, weakness, etc., you should consult a doctor as soon as possible to find out the cause under the guidance of a physician.