Characteristics of hematologic disorders include: lack of specificity of symptoms and signs, mostly systemic, and secondary more common than primary. 1. Lack of specificity of symptoms and signs: diseases of the blood system usually have blood cell involvement or changes in plasma composition, resulting in dysfunction, with similar symptoms, such as bleeding, anemia, infection, fever and other symptoms, lack of specificity, and need differential diagnosis. 2. Mostly systemic: the state of existence of blood in the body is in liquid form, which can be spread all over the body, therefore, blood diseases mostly have systemic manifestations, and can involve all organs and systems of the body. 3. Secondary diseases are more common than primary diseases: Almost all organ and system diseases in the whole body will involve the blood system, leading to changes in blood norms and other indexes, and some of them will cause serious and long-lasting abnormalities in blood norms. Diseases of the blood system have different characteristics from other diseases, which are determined by the characteristics of the hematopoietic system itself. In case of hematologic diseases, it is recommended to go to the hospital in time for diagnosis and treatment under the guidance of a physician.