The main causes of low large platelet ratio are bone marrow suppression and insufficient platelet production. Low large platelet ratio indicates that the proportion of large platelets to the total platelet ratio is low, indicating that the overall platelets show high maturity, the cause of this state may be bone marrow inhibition, insufficient platelet production. Insufficient platelet production: such as aplastic anemia, thrombocytopenia, taking drugs that cause bone marrow suppression, etc., will cause bone marrow hematopoietic failure, making it difficult for platelets to be produced, resulting in a low large platelet ratio. Therefore, when a patient has a low macroplatelet ratio, he/she should seek professional medical consultation and treatment in time to make a clear diagnosis, so as to avoid delaying his/her condition.