Platelet counting with a laser nephelometer.

A method for platelet counting is described, based on the Laser nephelometric principle. Experimental results are reported, together with the practical considerations for the standardisation and correlation of the method, and for application of the method in the routine biochemical laboratory. Venous blood, taken with EDTA-NaCL solution according to Schulz et al (1071, Z. Klin. Chem. Klin. Biochem. 9, 329-333) is used. The blood is centrifuged at 100 g for 10 min and 10 microliter of the supernatant is added to 3000 microliter of a suspending medium (dilution 1:80); 300 microliter platelet suspension are read in a nephelometer cuvet or tube against blank. The number of platelets per liter blood are determined with the aid of a standard curve. The sensitivity and reproducibility of the method, and the correlation with the "electronic coulter counting" method are satisfactory.