Before donating blood, blood samples will be tested, and those who pass the test will be excluded from most hematologic diseases and various infectious diseases. 1. Most hematologic diseases: including leukocytosis or thrombocytopenia. 2. Various infectious diseases: including AIDS, Hepatitis B virus, Hepatitis C virus and other blood-borne diseases. Failure to donate blood does not necessarily mean that you will suffer from any of the above diseases, because the results of the pre-donation test are only used as a criterion for judging whether to donate blood or not, and cannot be used as a basis for judging whether you are healthy or not. If you feel unwell and other symptoms, you should seek medical advice in time and under the guidance of a doctor, undergo a systematic examination to rule out related diseases, rather than relying on blood donation to rule out diseases.