Platelets 7 generally refers to the platelet count of 7 × 10^9 / L, this situation is an anomaly, indicating that the platelet count value is seriously low, causing serious low platelet causes acute leukemia, systemic lupus erythematosus, hypersplenism and so on. 1. Acute leukemia: it is a group of malignant clonal diseases originated from hematopoietic stem cells. When immature hematopoietic cells proliferate, normal hematopoiesis will be inhibited, which will lead to anemia, and platelet count of 7×10^9/L can be seen in the blood test, and the patient will have pale face, purpura of the skin, fever, and bleeding that is difficult to be stopped, and other phenomena. 2. Systemic lupus erythematosus (SLE): the cause of the disease is not yet confirmed, and it is related to genetic, endocrine, drug, immune abnormalities, etc. This disease will cause the involvement of many organs in the whole body, and it will also cause hematological system pathology, which will lead to thrombocytopenia, and the platelet count can be found to be 7×10^9/L, and the patient will have annular erythema, accompanied with prolonged low-grade fever and other phenomena. 3. Hypersplenism: mostly related to blood system diseases, infections, immune diseases, etc. Hypersplenism will reduce one or more kinds of blood cells in the body, so that the platelet count is found to be 7×10^9/L in the examination, and the patient will have abdominal distension, spontaneous bleeding of the gums and other phenomena. In addition, platelet aplasia, immune thrombocytopenia, etc. can cause platelet count of 7×10^9/L. It is recommended that the patient immediately seek medical attention to clarify the cause of the disease and then follow the doctor’s instructions for treatment.