Blood tests include a variety of tests, including routine blood tests, biochemical tests and serological tests, so many diseases can be detected through blood tests. For example, routine blood tests can detect many anemic diseases. If the hemoglobin concentration is lower than normal, and the average red blood cell volume, average red blood cell hemoglobin volume and average red blood cell hemoglobin concentration in peripheral blood are low, then the diagnosis of iron deficiency anemia is basically confirmed. If routine blood tests show normal white blood cell and red blood cell counts, but severely reduced platelet counts, there is also a possibility of immune thrombocytopenic purpura in this case. Blood biochemistry tests can diagnose diabetes if abnormally high blood glucose is found. If the blood lipids are abnormally increased, hyperlipidemia can be diagnosed. If the serological examination reveals a positive HIV antibody, the diagnosis of HIV carriers can be made.