The causes of low red blood cells after kidney transplantation may be the effect of drugs, abnormal erythropoietin and infectious diseases. 1. Drug effects: after kidney transplantation, patients often need to take immunosuppressants for a long time to control the rejection reaction after transplantation, such as azathioprine, cyclosporine A, etc. One of the common adverse reactions of these drugs is myelosuppressive reaction, which can cause hematopoietic dysfunction and anemia, which is manifested as low red blood cell value and decreased hemoglobin. 2. Erythropoietin abnormality: the kidneys can produce erythropoietin. Patients with kidney-related diseases, who have received kidney transplants due to the disease, some of them still cannot restore the normal level of erythropoietin production after the operation, resulting in a reduction of erythropoietin, leading to anemia and a decrease in red blood cells. 3. Infectious diseases: After kidney transplantation, due to taking immunosuppressant, the immunity of the body decreases, and it is easy to be complicated by infectious diseases, and infectious diseases may lead to chronic depletion of nutrients in the body, which leads to anemia, erythropoiesis and so on. Kidney transplant patients are advised to actively cooperate with doctors for examination, and go to the hospital in time when they find abnormal indicators or uncomfortable symptoms, identify the cause of the disease, and then follow the doctor’s instructions for treatment.