An overview of platelet indices and methods for evaluating platelet function in thrombocytopenic patients

Abstract

Thrombocytopenia is associated with bleeding risk. However, in thrombocytopenic patients, platelet count does not correlate with bleeding risk and other factors are thus likely to contribute to this risk. This review presents currently available platelet-related markers available on automated haematology analysers and commonly used methods for testing platelet function. The test principles, advantages and disadvantages of each test are described. We also evaluate the current literature regarding the clinical utility of the test for prediction of bleeding in thrombocytopenia in haematological and oncological diseases. We find that several platelet-related markers are available, but information about the clinical utility in thrombocytopenia is limited. Studies support that mean platelet volume (MPV) can aid diagnosing the cause of thrombocytopenia and low MPV may be associated with bleeding in thrombocytopenia. Flow cytometry, platelet aggregometry and platelet secretion tests are used to diagnose specific platelet function defects. The flow cytometric activation marker P-selectin and surface coverage by the Cone-and-Plate [let] analyser predict bleeding in selected thrombocytopenic populations. To fully uncover the clinical utility of platelet-related tests, information about the prevalence of platelet function defects in thrombocytopenic conditions is required. Finally, knowledge of the performance in thrombocytopenic samples from patients is essential. Platelets are essential in primary haemostasis, and it is evident that a low platelet count is a significant risk factor for bleeding (1). Thus, bleeding is a frequently occurring complication and may be the cause of death in thrombocytopenic patients (2, 3), but not all patients with thrombocytopenia experience bleeding. In a study of almost 30 000 platelet counts obtained from haematological and oncological patients, clinically significant bleeding (WHO grade ≥2) was experienced on only 25% of days where platelet count was ≤5 9 10 9 /L (3). When platelet count was between 6 and 80 9 10 9 /L, the risk of bleeding was 17% and did not seem to correlate with platelet count (3). Likewise, there was no clear association between platelet count and bleeding found in other studies among haematological or oncological patients (4,5). In other thrombocytopenic conditions such as liver cirrhosis or sepsis, the relation between platelet count and bleeding has only been sparsely investigated (6, 7).Thus, other factors obviously contribute to the risk of bleeding in thrombocytopenia. In this regard, the haemostatic capacity of platelets depends on both number and function.The aim of this review was therefore to describe the evidence for using platelet-related markers and methods for testing platelet function in assessment of spontaneous bleeding risk in thrombocytopenic patients. Automated haematology analysers PrinciplePlatelet count obtained by automated analysers deviates due to differences in the applied methodology and detection algorithms (8-10). The commonly us...

Platelet indices in Philadelphia-negative chronic myeloproliferative neoplasms / Indicii plachetari de volum în neoplasmele mieloproliferative cronice Philadelphia-negative

“…In our study we did not find an inverse correlation between MPV values and platelet count that Lance et al found [23]. The other platelet volume indices, PDW and P-LCR have been less studied in comparison to MPV [11,24]. In our study MPV and the others PVI, assessed through the impedance method, did not reveal a significant difference between values of patients and healthy controls.…”

Platelet parameters and expression of platelet membrane glycoprotein in childhood acute lymphoblastic leukemia

“…Research has shown that reduced myeloproliferative function leads to a decrease in PLT, while MPV is reduced or remains unchanged (Chandra et al, 2010). Vinholt et al (2014) suggested that the bleeding symptoms in thrombocytopenia patients may be related to a decrease in MPV. The results of this study indicated that childhood ALL incorporates thrombocytopenia and platelet dysfunction.…”

“…The extent of reduction in the number of platelets is a determinant to assess the risk of bleeding. Patients with a low platelet count diagnosed and treated for a long period of time presented a very small amount of bleeding; however, patients with high platelet counts faced serious bleeding; therefore, bleeding was said to be associated with platelet function (Vinholt et al, 2014). Platelets have a short life span, and are not easily preserved; this hinders the clinical detection of platelet function.…”

Coagulopathy in liver disease: Lack of an assessment tool

“…It remains the gold standard method for assessing platelet reactivity in both clinical and research settings. However, abnormal platelet aggregation studies (demonstrating hypofunction or hyperfunction) often lack correlation with clinical complications (bleeding or thrombosis) [14,15] . This method is useful for detecting platelet function defects that are congenital or secondary to medication.…”