Complete hemostasis achieved by factor XIII concentrate administration in a patient with bleeding after teeth extraction as a complication of aplastic anemia and chronic disseminated intravascular coagulation

How We Interpret Thrombosis with Thrombocytopenia Syndrome?

Platelets play an important role in hemostasis, and a low platelet count usually increases the risk of bleeding. Conditions in which thrombosis occurs despite low platelet counts are referred to as thrombosis with thrombocytopenia syndrome, including heparin-induced thrombocytopenia, vaccine-induced immune thrombotic thrombocytopenia, paroxysmal nocturnal hemoglobinuria, antiphospholipid syndrome, thrombotic microangiopathy (TMA), and disseminated intravascular coagulation. TMA includes thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (HUS), and atypical HUS. Patients with these pathologies present with thrombosis and consumptive thrombocytopenia associated with the activation of platelets and the coagulation system. Treatment varies from disease to disease, and many diseases have direct impacts on mortality and organ prognosis if therapeutic interventions are not promptly implemented. Underlying diseases and the results of physical examinations and general laboratory tests as part of a thorough workup for patients should promptly lead to therapeutic intervention before definitive diagnosis. For some diseases, the diagnosis and initial treatment must proceed in parallel. Utilization of not only laboratory tests but also various scoring systems is important for validating therapeutic interventions based on clinical information.

Distinguishing immune-mediated thrombotic thrombocytopenic purpura from septic disseminated intravascular coagulation using plasma levels of haptoglobin and factor XIII activity

Background

Both immune-mediated thrombotic thrombocytopenic purpura (iTTP) and septic disseminated intravascular coagulation (DIC) are life-threatening disorders developed by platelet-consuming microvascular thrombi and necessitate immediate therapeutic interventions. Although severe deficiencies of plasma haptoglobin in iTTP and factor XIII (FXIII) activity in septic DIC have been reported, few studies have focused on the possibility of using these markers to distinguish between iTTP and septic DIC.

Objectives

We investigated whether the plasma levels of haptoglobin and FXIII activity could be helpful for differential diagnosis.

Methods

Thirty-five patients with iTTP and 30 with septic DIC were enrolled in the study. Patient characteristics, coagulation, and fibrinolytic markers were collected from the clinical data. Plasma haptoglobin and FXIII activities were measured using chromogenic Enzyme-Linked Immuno Sorbent Assay and an automated instrument, respectively.

Results

The median plasma haptoglobin level was 0.39 mg/dL and 54.20 mg/dL in the iTTP and septic DIC groups, respectively. The median plasma FXIII activities were 91.3% and 36.3% in the iTTP and septic DIC groups, respectively. In the receiver operating characteristic curve analysis, the cutoff level of plasma haptoglobin was 2.868 mg/dL and the area under the curve was 0.832. The cutoff level for plasma FXIII activity and the area under the curve were 76.0% and 0.931, respectively. The thrombotic thrombocytopenic purpura (TTP)/DIC index was defined by FXIII activity (percentage) and haptoglobin (milligrams per decilitre). Laboratory TTP was defined as an index ≥60 and laboratory DIC <60. The sensitivity and specificity of the TTP/DIC index were 94.3% and 86.7%, respectively.

Conclusion

The TTP/DIC index, composed of plasma levels of haptoglobin and FXIII activity, is useful in differentiating iTTP from septic DIC.

Coagulopathy and Fibrinolytic Pathophysiology in COVID-19 and SARS-CoV-2 Vaccination

Coronavirus Disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is frequently complicated by thrombosis. In some cases of severe COVID-19, fibrinolysis may be markedly enhanced within a few days, resulting in fatal bleeding. In the treatment of COVID-19, attention should be paid to both coagulation activation and fibrinolytic activation. Various thromboses are known to occur after vaccination with SARS-CoV-2 vaccines. Vaccine-induced immune thrombotic thrombocytopenia (VITT) can occur after adenovirus-vectored vaccination, and is characterized by the detection of anti-platelet factor 4 antibodies by enzyme-linked immunosorbent assay and thrombosis in unusual locations such as cerebral venous sinuses and visceral veins. Treatment comprises high-dose immunoglobulin, argatroban, and fondaparinux. Some VITT cases show marked decreases in fibrinogen and platelets and marked increases in D-dimer, suggesting the presence of enhanced-fibrinolytic-type disseminated intravascular coagulation with a high risk of bleeding. In the treatment of VITT, evaluation of both coagulation activation and fibrinolytic activation is important, adjusting treatments accordingly to improve outcomes.

Therapeutic Strategies for Disseminated Intravascular Coagulation Associated with Aortic Aneurysm

Aortic aneurysms are sometimes associated with enhanced-fibrinolytic-type disseminated intravascular coagulation (DIC). In enhanced-fibrinolytic-type DIC, both coagulation and fibrinolysis are markedly activated. Typical cases show decreased platelet counts and fibrinogen levels, increased concentrations of fibrin/fibrinogen degradation products (FDP) and D-dimer, and increased FDP/D-dimer ratios. Thrombin-antithrombin complex or prothrombin fragment 1 + 2, as markers of coagulation activation, and plasmin-α₂ plasmin inhibitor complex, a marker of fibrinolytic activation, are all markedly increased. Prolongation of prothrombin time (PT) is not so obvious, and the activated partial thromboplastin time (APTT) is rather shortened in some cases. As a result, DIC can be neither diagnosed nor excluded based on PT and APTT alone. Many of the factors involved in coagulation and fibrinolysis activation are serine proteases. Treatment of enhanced-fibrinolytic-type DIC requires consideration of how to control the function of these serine proteases. The cornerstone of DIC treatment is treatment of the underlying pathology. However, in some cases surgery is either not possible or exacerbates the DIC associated with aortic aneurysm. In such cases, pharmacotherapy becomes even more important. Unfractionated heparin, other heparins, synthetic protease inhibitors, recombinant thrombomodulin, and direct oral anticoagulants (DOACs) are agents that inhibit serine proteases, and all are effective against DIC. Inhibition of activated coagulation factors by anticoagulants is key to the treatment of DIC. Among them, DOACs can be taken orally and is useful for outpatient treatment. Combination therapy of heparin and nafamostat allows fine-adjustment of anticoagulant and antifibrinolytic effects. While warfarin is an anticoagulant, this agent is ineffective in the treatment of DIC because it inhibits the production of coagulation factors as substrates without inhibiting activated coagulation factors. In addition, monotherapy using tranexamic acid in cases of enhanced-fibrinolytic-type DIC may induce fatal thrombosis. If tranexamic acid is needed for DIC, combination with anticoagulant therapy is of critical importance.

Management of disseminated intravascular coagulation associated with aortic aneurysm and vascular malformations

Aortic aneurysms and vascular malformations are sometimes associated with disseminated intravascular coagulation (DIC). A typical blood coagulation test shows decrease in platelet count and fibrinogen, and increases in fibrin/fibrinogen degradation products (FDP) and D-dimer. The coagulation activation marker thrombin-antithrombin complex (TAT) and the fibrinolysis activation marker plasmin-α₂ plasmin inhibitor (PIC) are significantly increased. α₂ plasmin inhibitor (α₂PI) is significantly reduced. Since no prolongation of prothrombin time (PT) is noticeable and activated partial thromboplastin time (APTT) is shortened in some cases, DIC cannot be diagnosed or ruled out by PT and APTT alone. The cornerstone of treatment for DIC is to treat the underlying disease. However, surgery is not possible in some cases. Follow-up may be appropriate in patients with abnormal results from coagulation tests and no bleeding. However, pharmacotherapy is often required in cases with bleeding. Unfractionated heparin, low molecular weight heparin, protease inhibitors, recombinant thrombomodulin, direct oral anticoagulants, and factor XIII preparations are effective. If PIC is significantly increased and α₂PI is significantly decreased, or if the bleeding is severe, tranexamic acid is used as an antifibrinolytic therapy with anticoagulant therapy. In such cases, attention should be paid not only to TAT but also changes in PIC.