Low platelets can not be found the cause of the disease need to be blood smear test, bone marrow aspiration test, antinuclear antibody test, etc., to exclude accidental, secondary, other blood diseases influence and other factors. 1. Low platelets may be pseudo-thrombocytopenia, a blood smear can be done to verify whether there is any abnormality of platelets and white blood cells in the blood smear. 2. To rule out thrombocytopenia caused by other blood diseases, such as aplastic anemia, chronic granulocytic leukemia, etc., bone marrow aspiration is needed to check the quantity and quality of megakaryocytes in the bone marrow to rule out other blood diseases. 3. If the body’s immune system is attacked, resulting in immune disorders, which can also cause thrombocytopenia, such as lupus erythematosus, dry syndrome, etc., can be supplemented with antinuclear antibody test. Low platelets can not be found the cause of the disease, may be due to the examination is not in place, it is recommended to repeat several times under the guidance of the doctor, in order to exclude the possibility of misdiagnosis.