Analytical Comparison of Impedance and Optical Platelet Counting in the Presence of Platelet Mimickers in Hematology Analysers

Accurate and precise platelet counting is essential in disease monitoring and treatment, and it is a vital research tool for standardizing counts within whole blood, platelet rich plasma or purified platelet preparation. It is said that with development of two-dimensional analysis using light scatter or fluorescence, limitations with one-dimensional analysis like impedance method, are reduced. This study is about evaluating significance of effects on platelet counting in presence of common platelet confounders by comparing two methods, impedance and optical, in the same analyzer. OBJECTIVE: To compare the two methods of platelet counting, impedance and optical, in automated hematology analyzer, in presence of platelet confounders. MATERIAL AND METHODS: A retrospective analytical study was conducted over a period of two months. Platelet count of patients with microcytosis, and thrombocytopenia were compared against the platelet count of the controls with normal blood picture and results were analyzed. RESULTS: One hundred and forty patients with microcytosis and one fifty-seven with thrombocytopenia were compared with controls. Platelet count was higher in 48% of patients by optical method and only 2% by impedance method in control subjects. Presence of microcytosis resulted in higher platelet count by impedance method 18%. Thrombocytopenia resulted in exaggeration of this phenomenon with 31% of platelet count showing higher values. There was no correlation between platelet count (optical method) and difference between platelet count by two methods. CONCLUSION: Presence of microcytosis and thrombocytopenia results in significant increase in platelet count by impedance method.