Erythrocyte counting techniques – evaluation of Red Blood Cell Count (RBC) with
Bürker or Thoma hemacytometer counting grid (chamber).
Elements:
1. Bürker or Thoma hemacytometer (chamber) contains a net, which forms squares (dimension
of the side 1/20 mm and the surface of the square is 1/400mm2). The height of the chamber
after covering with a cover glass is 0.1 mm. It means that the volume of the single cuboid is
1/20mm x 1/20mm x 1/10 mm = 1/4000 mm;. Cover glass should be stuck to the
hemacytometer to form color Newtonian rings.
2. Hayem's solution (0.25g HgCl2, 0.5g NaCl, 2.5g Na2SO4 and distilled water up to 100mL) or
2-3% saline. The solution should be used to dilute blood (ratio l vol. of blood per 99 or 199
vol. of Hayem's solution).
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Procedure:
Dilute blood with Hayem's solution.
Put a cover glass on the hemacytometer to form a chamber which volume is 1/4000 mm 3.
Inject some prepared blood into the chamber.
Count RBC in 80 small cuboids.
Count the average value of erythrocytes per one small cuboid.
Estimate RBC count by multiplication of average value of erythrocytes per cuboid, rate of
dilution in Hayem's solution and inverse of the cuboid volume to obtain the number of
erythrocytes per volume of 1mm3 (µL).
RBC count (per I µL) = Number per cuboid x rate of dilution x 4000
Reference values of RBC (million/ µL):
Adult female - 3.6 ÷ 5.0,
Adult male - 4.2 ÷ 5.4.
1/5 mm
1/5 mm
1/20 mm