[New method of thrombocyte counting. Technic of electronic counting of low thrombocyte concentrations in peripheral...

Starting from recent studies of Balleisen (1972) and Schmidt et al. (1973) about automated counting of platelets an automated method has been developed for accurate platelet counting at very low platelet concentration of peripheral blood. The method can be summarized as follows: 0,1 ml anticoagulated venous blood (Na-EDTA or polystyrol tubes containing EDTA powder) or capillary blood from finger tips was diluted with 20 ml of a mixture of Isoton-Periston-(Bayer-)Na2-EDTA (22:2:1 vol.) in polystyrol tubes. After 5 min centrifugation at 85 g, using an angle head and decantation into a polystyrol tube, second centrifugation. Decantation in a Coulter glass and counting at aperture 8, attenuation 0.500 and theshold 6 respectively 70 using at 70 mikron capillary. Counts at threshold 70 (erythrocyte counts) were subtracted from counts at threshold 6 (platelets and erythrocytes); to calculate platelet counts/mm3 multiplication by factor 2 at undiluted venous or capillary blood. The mean variation coefficient of our method being 4,1%, counting of platelets is possible with the accuracy of other automated methods at normal platelet concentration. At very low platelet counts our method seems to be the most accurate laboratory method for platelet counting.