112 - Thrombocytopenia: the role of clinical laboratory
Autor(s): P. Doretto, P. Cappelletti
Issue: RIMeL - IJLaM, Vol. 3, N. 3-S1, 2007 (MAF Servizi srl ed.)
Page(s): 112-119
The laboratory workup of thrombocytopenia (PLT <150.000/L) should start with an automatic precise and accurate count, supported by instrumental information as well as additional parameters. In spite of instrumental improvement, based on the integration of the impedance principle along with the light-scatter and cytofluorimetric methods, bidimensional optic measurements and new computation algorithms, still the accuracy of platelets count represent a real challenge. The introduction of a new method based on immunologic-cytofluorometric reference, presented by ICSH in 2001, is considered to be a great step towards a more precise platelets count. However, the instrumental performance in low platelets count does not satisfy the clinical necessities, if that the prophylactic platelets transfusion threshold is <10.000/L. Besides confirming thrombocytopenia, the examination of the peripheral blood smear allows the diagnosis of platelets morphologic abnormalities that could lead to congenital thrombocytopenias or thrombocytopathies. If the clinical picture and the absence of morphologic abnormalities should lead to autoimmune thrombocytopenia, then autoimmune screening tests and viral tests are warranted. The antiplatelets antibodies assays present specificity limitations and more sensitivity problems, and should be reserved only for atypical or complicate forms. In this specific case, in order to differentiate between thrombocytopenias due to increased destruction vs those due to decreased production, cytofluorimetric count of reticulated forms, as well as glycocalicin and thrombopoietin determination could be performed. Whenever leukocyte and erythrocyte morphologic abnormalities are detected, along with clinical pictures suggestive for other hematologic pathologies, a bone marrow biopsy coupled to other specific tests should be taken into account.