The impact of platelet indices in the evaluation of different causes of platelet count disorder

BACKGROUND: Some of the platelet count disorders have no single clinical or laboratory diagnostic finding and bone marrow examination may be required which is invasive, time consuming. Platelet indices are readily available parameters by recent hematology autoanalyzers and could provide some important information and can differentiate between several mechanisms of platelet disorders. AIM OF STUDY: To evaluate and interpret different platelet indices (plateletcrit, mean platelet volume [MPV], platelet distribution width [PDW], platelet-large cell ratio [P-LCR]) in patients with quantitative platelet disorders. PATIENTS AND METHODS: A prospective cross-sectional study was carried out from November 2019 to September 2020 in different Iraqi hematology centers and conducted on 160 adult patients from 3 hematology centers, from November 2019 to September 2020, 80 patients have thrombocytopenia, and 80 patients with thrombocytosis. Platelet count and indices (MPV, P-LCR, PDW) were determined using automated analyzers. For each hematological parameter, two measurements were taken at different time interval and the mean value of these two records was relied on. RESULTS: A significant increase in all platelet indices (MPV, PDW, P-LCR) with cutoff values of 7.9 femtoliters (fl), 15.3%, and 12.6%, respectively, P = 0.000 was observed in primary thrombocytosis, with 90% sensitivity for MPV and 50% specificity for PDW. In immune thrombocytopenia (ITP), all platelet indices (MPV, PDW, and P-LCR) were significantly higher than in hypoproductive thrombocytopenia with cutoff values of 7.9fl, 15.3%, and 12.9%, respectively. MPV has a sensitivity of 97% and specificity of 50%, P-LCR had a sensitivity of 100%, and PDW had a sensitivity and specificity of 77% and 70%, respectively. CONCLUSIONS: These abnormalities in platelet indices are of value for differentiation of platelet quantitative disorders, higher value in ITP in comparison with other causes of thrombocytopenia, and for primary thrombocytosis, the value is higher than reactive thrombocytosis.