Red blood cell be used for blood transfusions. Several blood tests involve red blood cells. These include a "RBC count" (the number of red blood cells per volume of blood), calculation of the hematocrit (percentage of blood volume occupied by red blood cells), and the erythrocyte sedimentation rate. The blood type needs to be determined to prepare for a blood transfusion or an organ transplantation. Many diseases involving red blood cells are diagnosed with a blood film (or peripheral blood smear), where a thin layer of blood is smeared on a microscope slide. This may reveal abnormalities of red blood cell shape and
White blood cell underlying cause, though the cause may not always be found. The complete blood cell count is a blood panel that includes the overall WBC count and various subsets such as the absolute neutrophil count. Reference ranges for blood tests specify the typical counts in healthy people. TLC- (Total leucocyte count): Normal TLC in an adult person is 6000-8000WBC/mm^3 of blood. DLC- (Differential leucocyte count): Number/ (%) of different type of leucocyte in per cubic mm. of blood. White blood cell White blood cells (also called leukocytes or leucocytes and abbreviated as WBCs) are the cells of the immune system that