Depending on our state of health, the numbers of molecules and cells in our blood will vary. When doctors request a particular blood test, specific molecules and cells are counted within our blood sample. In the lab, a test tube blood sample is spun in a centrifuge that separates it into three layers. Red cells, white cells and platelets are located in the first two layers and the numbers of each type of cell is counted and reported in a lab report. The third layer, plasma, can also be tested in many ways to provide information.
Lab reports give information on hematology, blood cells, and data about plasma.
It is important to remember that these are approximate numbers and tests can be influenced by many things. Measures immune cells. If low, indicates suppressed immunity, viral infection. If high, can indicate bacterial infection. Shows the percentage of blood occupied with red cells.