The blood includes red blood cells, white blood cells, platelets and clotting factors. The main functions of the blood are to carry oxygen, provide immunity and maintain good blood clotting. Most diseases of the blood system are refractory. You should see a hematologist when the following signs and symptoms occur 1.Anemia symptoms: fatigue and weakness, palpitation and shortness of breath, aggravation after activity, dullness, dizziness, loss of appetite, insomnia and dreaminess, weakness, sweating, hair loss, etc. 2, bleeding tendency: such as nosebleeding, gum bleeding, vomiting blood, black stool, hematuria, excessive menstruation, skin bleeding spots, purpura and bruises, as well as bleeding from the eyes and oral mucosa, should be highly alert to the possibility of blood disorders. 3. Fever: low fever, high fever or fever of unknown origin. Repeated infections and easy to catch a cold. 4.Jaundice: yellow body, yellow eyes, yellow urine or soy sauce-colored or wine-colored urine, etc. 5.Liver and spleen enlargement: enlargement of liver and spleen, especially significant and significant, should all be considered as a possibility of hematological disease. 6.Lymph node enlargement: It is one of the common signs of hematological diseases, especially malignant tumors of the hematopoietic system such as leukemia and lymphoma. 7.Bone, joint and related signs and symptoms: especially pressure pain in the sternum and long-term back pain need to be highly alert to the possibility of blood diseases. 8.Other symptoms and signs that may be related to hematological diseases: itchy skin, recurrent oral ulcers, blood hyperviscosity syndrome, etc. 9.Recurrent proteinuria: such as multiple myeloma.