Clinical Usefulness of Measurement of Reticulated Platelets by Thiazole Orange in Idiopathic Thrombocytopenic Purpura / 대한임상병리학회지

ABSTRACT

BACKGROUND: Reticulated platelets (RP) are young platelets with a high mRNA that are newly produced from the bone marrow. Thiazole orange (TO) has been a RNA staining fluorescent dye for reticulocyte, and used for RP recently. The increased percentage of RP (RP%) reflects immaturity and hematopoietic activity of platelets, therefore it may be useful for the diagnosis of idiopathic thrombocytopenic purpura (ITP). METHODS: To assess the usefulness of RP in diagnosing ITP, we compared with RP%s of 50 ITP patients, 35 thrombocytopenic patients due to impaired production and 87 heathly normal controls. Platelets were stained with TO dye, followed by flowcytometric analysis. Platelet associated IgG (PAIgG) was also measured with the same samples. The standard gate was used as a reference with the unstained sample from a normal subject and the RP% was expressed as the percentage of TO positive cells of platelets. RESULTS: The RP% of patients with ITP was significantly higher than those of thrombocytopenia due to impaired platelet production and healthy controls (24.4+/-14.3% vs 8.6+/-5.2% and 8.0+/-5.1%, respectively). There was negative correlation between the platelet count and RP%, and positive correlation between MPV and RP%. In diagnosing for ITP, the sensistivity and specificity of RP% were 81% and 92%, respectively, and more valuable than those of PAIgG test. Using RP% and PAIgG at the same time, the diagnostic efficiency for ITP was not improved. The RP% of an ITP patient was changed to correspond with the disease progression, and that of an AML patient following chemotherapy was increased to precede the rising of the platelet count. CONCLUSION: It suggest that the measurement of reticulated platelets is a very useful test for diagnosis of ITP, furthermore it can be used to estimate the thrombopoietic activity before bone marrow examination.