No 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...

Background The course of coronavirus disease 2019 (COVID-19) seems to be aggravated by air pollution, and some industrial chemicals, such as the perfluorinated alkylate substances (PFASs), are immunotoxic and may contribute to an association with disease severity. Methods From Danish biobanks, we obtained plasma samples from 323 subjects aged 30–70 years with known SARS-CoV-2 infection. The PFAS concentrations measured at the background exposures included five PFASs known to be immunotoxic. Register data was obtained to classify disease status, other health information, and demographic variables. We used ordered logistic regression analyses to determine associations between PFAS concentrations and disease outcome. Results Plasma-PFAS concentrations were higher in males, in subjects with Western European background, and tended to increase with age, but were not associated with the presence of chronic disease. Of the study population, 108 (33%) had not been hospitalized, and of those hospitalized, 53 (16%) had been in intensive care or were deceased. Among the five PFASs considered, perfluorobutanoic acid (PFBA) showed an unadjusted odds ratio (OR) of 2.19 (95% confidence interval, CI, 1.39–3.46) for increasing severities of the disease. Among those hospitalized, the fully adjusted OR for getting into intensive care or expiring was 5.18 (1.29, 20.72) when based on plasma samples obtained at the time of diagnosis or up to one week before. Conclusions Measures of individual exposures to immunotoxic PFASs included short-chain PFBA known to accumulate in the lungs. Elevated plasma-PFBA concentrations were associated with an increased risk of a more severe course of COVID-19. Given the low background exposure levels in this study, the role of exposure to PFASs in COVID-19 needs to be ascertained in populations with elevated exposures.

Much of the underlying disease mechanisms of COVID-19 infection is yet to be learned. It has become clear, that COVID-19 has profound impact on the haematological system, including white blood cell morphology, but systematic reports are lacking. In the present Morphological changes in COVID-19 study, we evaluated haematological and morphological parameters for patients with COVID-19 and patients with suspected COVID-19 infection but negative real-time polymerase chain reaction (RT-PCR) admitted to Kolding Hospital and Odense University hospital between the 10 th of March and the 16 th of April 2020. COVID-19 positive patients were matched for age and gender with non-COVID-19 patients. We found COVID-19 patients to have lower white blood cell, neutrophil, lymphocyte, monocyte, and platelet count compared to non-COVID-19 patients. Mean platelet volume, platelet distribution width, and platelet large cell ratio was conversely higher in COVID-19 patients. In terms of red blood cell indices, only minor differences were found when comparing COVID-19 to non-COVID-19 patients. Patients with severe COVID-19 disease had higher immature granulocyte count and lower neutrophil and platelet count than patients with non-severe disease courses. The majority of non-COVID-19 patients had a normal morphological examination (83.3%), compared to 14.8% of COVID-19 patients. Hypogranulated neutrophils were more frequent in COVID-19 patients, but no significant differences were found for neutrophil hypergranulation, neutrophil vacuolation, plasmatoid cells, plasma cells, giant platelets, band neutrophils, or hypersegmented neutrophils. In conclusion, several haematological morphological abnormalities are more frequent in patients with COVID-19 disease, there are indications of platelets playing a fundamental role in the pathophysiology of the disease.