Letter to the Editor 853 This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

The prothrombin time (PT) represents the most commonly used coagulation test in clinical laboratories. The PT is mathematically converted to the international normalized ratio (INR) for use in monitoring anticoagulant therapy with vitamin K antagonists such as warfarin in order to provide test results that are adjusted for thromboplastin and instrument used. The INR is created using two major PT ‘correction factors’, namely the mean normal PT (MNPT) and the international sensitivity index (ISI). Manufacturers of reagents and coagulometers have made some efforts to harmonizing INRs, for example, by tailoring reagents to specific coagulometers and provide associated ISI values. Thus, two types of ISIs may be generated, with one being a ‘general’ or ‘generic’ ISI and others being reagent/coagulometer‐specific ISI values. Although these play a crucial role in improving INR results between laboratories, these laboratories reported INR values are known to still differ, even when laboratories use the same thromboplastin reagent and coagulometer. Moreover, ISI values for a specific thromboplastin can vary among different models of coagulometers from a manufacturer using the same method for clot identification. All these factors can be sources of error for INR reporting, which in turn can significantly affect patient management. In this narrative review, we provide some guidance to appropriate ISI verification/validation, which may help decrease the variability in cross laboratory reporting of INRs.

The cardinal pathology of coronavirus disease 2019 (COVID-19) is a primary infection of pulmonary tract cells by severe acute respiratory syndrome coronavirus 2, provoking a local inflammatory response, often accompanied by cytokine storm and acute respiratory distress syndrome, especially in patients with severe disease. Systemic propagation of the disease may associate with thrombotic events, including deep vein thrombosis, pulmonary embolism, and thrombotic microangiopathy, which are important causes of morbidity and mortality in patients with COVID-19. This narrative review describes current knowledge of the pathophysiological mechanisms of COVID-19-associated coagulopathy, with focus on prothrombotic changes in hemostatic mediators, including plasma levels of clotting factors, natural anticoagulants, components of fibrinolytic system, and platelets. It will also highlight the central role of endothelial cells in COVID-19-associated coagulopathy. This narrative review discusses also potential therapeutic strategies for managing thrombotic complications. Awareness by medical experts of contributors to the pathogenesis of thrombotic events in COVID-19 is imperative to develop therapeutics not limited to regular anticoagulants. Instituting cooperation among medical personnel and researchers may lessen this novel virus' impact now, and in the event of recurrence.

No abstract

No abstract

Coronavirus disease 2019 (COVID-19) is a new medical challenge for all individuals, especially for those with underlying disorders, such as congenital bleeding disorders (CBDs). Therefore, the pandemic might significantly change the behaviour of patients with CBDs and results in some challenges. In the present study, we assessed the main challenges of COVID-19 infection to patients with CBDs. Data were collected from medical files and interviews of patients with CBDs who had COVID-19 infection. Follow-ups were performed on patients who had active severe acute respiratory syndrome coronavirus 2 infection between April and October 2020. All patients were interviewed by an expert in order to collect the pertinent data. Some questions were about patients’ preventive behaviors and feelings prior to infection, and some were about the consequences of infection on patients’ replacement therapy and bleeding management. Among 25 patients, infection and death of loved ones (n: 7, 28%), and their own (n: 5, 20%) or family members’ (n: 1, 4%) infection, and the resulting economic burden (n: 2, 8%) were main concerns. Six patients experienced depression during the pandemic. The pandemic caused all severely affected patients but one (n: 11, 92%) to abandon replacement therapy. However, two received on-demand therapy after exacerbation of their bleeding. Only one (25%) of four patients on prophylaxis received in-home therapy, whereas the others (75%) abandoned prophylaxis. It seems that COVID-19 infection has great consequences on the lives of patients with CBDs, causing some to take dangerous actions, such as abandonment of their treatment. Healthcare systems, and healthcare providers, should have an appropriate strategy for management of patients with CBDs that prevents infection and provides timely replacement therapy.

Congenital factor X (FX) deficiency is an extremely rare, bleeding disorder with an estimated incidence of one per 1 million. Patients with severe FX deficiency (FX:C < 1%) demonstrate a wide spectrum of serious clinical presentations, including hemarthrosis, hematoma, gastrointestinal (GI) bleeding, intracranial hemorrhage (ICH), and umbilical cord bleeding. 1 In fact, severe FX deficiency, with a high rate of life-threatening bleeding, is the second-most severe, rare coagulation factor deficiency (RCFD) after FXIII deficiency. 1,2 Although homozygotes are at risk of severe bleeding, heterozygotes usually are asymptomatic, but postsurgical bleeding or bleeding after childbirth may occur. 1,2 Other risk factors can increase the risk of bleeding in FX deficiency, and coronavirus disease 2019 (COVID-19), a new medical challenge, could affect the patient's bleeding or thrombotic tendency. 3 COVID-19, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents an enormous challenge for everyone, especially for those with underlying risk factors such as cardiovascular disease, diabetes, obesity, and renal failure. Age and male sex are other risk factors. 4 Limited data are available regarding the effect of COVID-19 on patients with congenital bleeding disorders (CBDs), particularly RCFDs. 5 It has been shown that hypercoagulability-related adverse consequences are less common among patients with CBDs, at least in those with moderate-to-severe deficiency, but further studies, including our ongoing work on a large number of patients, are required. 5 Although there are several

No abstract