What is EO in a blood test


Eosinophil granulocyte in the blood smear © Dr. Gerhard Weigl

The eosinophils are involved in the defense against parasites (e.g. worms and lice) as well as in allergies and autoimmune reactions.

The determination of the eosinophils in the blood is carried out by examining the differential blood count.

  • The differential blood count is either made automatically by the blood count analyzer: automatic differential blood count.
  • Or the blood is smeared, colored and counted by hand in the laboratory: manual differential blood count.

The values ​​of the differential blood count consist of two numbers for each cell group (neutrophils, basophils, eosinophils, lymphocytes and monocytes):

  • Relative value in percent (%):
    • This always relates to the proportion of the corresponding cell group of white blood cells in relation to the total leukocyte count.
    • Consequently, the sum of the percentages of the cell groups of the white blood cells must always add up to 100 percent.
  • Absolute value in giga per liter:
    • The sum of the absolute numbers of the cell groups of the white blood cells must result in the total white blood cell count.