title: Accuracy of low electronic platelet counts using platelet distribution curves.
abstract: At low platelet levels electronic counts are inaccurate because background counts are an increasingly important contribution to the total count. In this study the background contribution was selectively eliminated by coupling a multichannel particle size analyzer (Coulter Channelyzer II) to an electronic counter (Coulter ZBI). Platelet counts below 50 x 10(9)/l required an adjustment of the lower threshold in 11 of 15 specimens. Non-platelet counts averaged 18 percent of the platelet particle count with a maximum value of 50 percent. In contrast, platelet counts between 50 to 100 x 10(9)/l required only a minimum adjustment of the lower threshold and extraneous counts averaged only 2.7 percent of the platelet particle count. Phase platelet counts ranging from 4.0 x 10(9)/l to 115 x 10(9)/l were compared in ZBI-Channelyzer counts in 30 patients. The electronic counts showed good agreement with the reference method. Results were statistically analyzed using linear regression analysis and paired t tests. Technical errors involved in electronic and visual platelet counts are discussed.
mesh_terms: D001792:Blood Platelets; D002469:Cell Separation; D004583:Electrons; D006801:Humans; D010976:Platelet Count; D013921:Thrombocytopenia / Q000097:blood