Acquired disorders of platelet function

Chemotherapy-Associated Thrombotic Microangiopathy

Thrombotic microangiopathy (TMA) is a syndrome of microangiopathic hemolytic anemia and thrombocytopenia with end-organ dysfunction. Although the advent of plasma exchange, immunosuppression, and complement inhibition has improved morbidity and mortality for primary TMAs, the management of secondary TMAs, particularly drug-induced TMA, remains less clear. TMA related to cancer drugs disrupts the antineoplastic treatment course, increasing the risk of cancer progression. Chemotherapeutic agents such as mitomycin-C, gemcitabine, and platinum-based drugs as well as targeted therapies such as antiangiogenesis agents and proteasome inhibitors have been implicated in oncotherapy-associated TMA. Among TMA subtypes, drug-induced TMA is less well-understood. Treatment generally involves withdrawal of the offending agent and supportive care targeting blood pressure and proteinuria reduction. Immunosuppression and therapeutic plasma exchange have not shown clear benefit. The terminal complement inhibitor, eculizumab, has shown promising results in some cases of chemotherapy-associated TMA including in re-exposure. However, the data are limited, and unlike in primary atypical hemolytic uremic syndrome, the role of complement in the pathogenesis of drug-induced TMA is unclear. Larger multicenter studies and unified definitions are needed to elucidate the extent of the problem and potential treatment strategies.

The utility of therapeutic plasma exchange in Hyperviscosity syndrome associated with juvenile rheumatoid arthritis: A case report

Hyperviscosity syndrome (HVS) is a life-threatening syndrome caused by high concentrations of large plasma proteins like IgM, rheumatoid factor, and other immune complexes, leading to increased blood viscosity and symptoms such as visual abnormalities, neurological impairment, bleeding diathesis, and thrombosis. While Waldenström's macroglobulinemia accounts for 80% to 90% of cases, HVS may develop in other clinical settings characterized by elevations in plasma proteins. Limited evidence currently exists describing the safety and efficacy of therapeutic plasma exchange (TPE) for the management of HVS secondary to non-neoplastic conditions. We report a case of recurrent HVS associated with juvenile rheumatoid arthritis and Felty syndrome that demonstrated improvement in clinical symptoms following initiation of TPE. These findings suggest that TPE may be utilized as an adjunct treatment option in patients with HVS secondary to autoimmune disorders.

Clinical Implications of Thrombocytopenia for the Cirrhotic Patient

Thrombocytopenia is a frequent complication in patients with cirrhosis. As many as 84% of patients with cirrhosis have thrombocytopenia, and it is an independent variable indicative of advanced disease and poor prognosis. Although there is great concern that it may aggravate bleeding during surgical procedures, there is limited evidence to inform decisions regarding the treatment of cirrhotic patients with thrombocytopenia undergoing invasive procedures. Finally, there is evidence that platelets play a significant role in liver regeneration. In this report, the clinical implications of thrombocytopenia in cirrhotic patients are reviewed. The utility of platelet counts in the prognosis of cirrhosis and relationship to complications of advanced liver disease, including portal hypertension, esophageal varices, and hepatocellular carcinoma. The impact of low platelet counts on bleeding complications during invasive procedures is outlined. Finally, the role of platelets and potential adverse impact in liver regeneration is reviewed.

Early time course of major bleeding on antiplatelet therapy after TIA or ischemic stroke

Objective

To study the early time course of major bleeding and its subtypes in patients with cerebral ischemia on dual and single antiplatelet therapy.

Methods

We performed a post hoc analysis on individual patient data from 6 randomized clinical trials (Clopidogrel Versus Aspirin in Patients at Risk of Ischaemic Events [CAPRIE], Second European Stroke Prevention Study [ESPS-2], Management of Atherothrombosis With Clopidogrel in High-Risk Patients [MATCH], Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management, and Avoidance [CHARISMA], European/Australasian Stroke Prevention in Reversible Ischaemia Trial [ESPRIT], and Prevention Regimen for Effectively Avoiding Second Strokes [PRoFESS]) including 45,195 patients with a TIA or noncardioembolic ischemic stroke. We studied incidence rates of bleeding per antiplatelet regimen stratified by time from randomization (≤30, 31–90, 91–180, 181–365, >365 days). We calculated incidence rates per trial and pooled estimates with random-effects meta-analysis. We performed Poisson regression to assess differences between time periods with adjustment for age and sex.

Results

The incidence of major bleeding on aspirin plus clopidogrel and aspirin plus -dipyridamole was highest in the first 30 days, 5.8 and 4.9 per 100 person-years, respectively, and was significantly higher than at 31 to 90 days (rate ratio 1.98, 95% confidence interval 1.16–3.40 for aspirin plus clopidogrel; rate ratio 1.94, 95% confidence interval 1.24–3.03 for aspirin plus dipyridamole). Incidence rates on aspirin and clopidogrel monotherapy were 2.8 and 2.5 per 100 person-years, respectively, in the first 30 days, with no significant change over time. The time course was similar for gastrointestinal bleeds. There was no early excess of intracranial hemorrhage in patients on either dual or single antiplatelet therapy.

Conclusion

Dual antiplatelet therapy is associated with high early risks of major and gastrointestinal bleeding that decline after the first month in trial cohorts.

Acquired platelet disorders

In contrast to congenital platelet disorders, which are rare, acquired platelet dysfunctions are more common in clinical practice. Their main causes are medications and systemic/hematologic diseases. Typical clinical manifestations are mucosal bleeding, epistaxis, or superficial epidermal bleeding normally of modest entity. In most cases, the molecular mechanisms underlying impaired platelet function are not fully established, making it difficult to optimize patient care. We here provide a short overview of the various forms of acquired platelet disorders, with a particular focus on recent mechanistic studies on platelet dysfunction in von Willebrand disease.

Non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women with bleeding disorders

BACKGROUND

Heavy menstrual bleeding without an organic lesion is mainly due to an imbalance of the various hormones which have a regulatory effect on the menstrual cycle. Another cause of heavy menstrual bleeding with no pelvic pathology, is the presence of an acquired or inherited bleeding disorder. The haemostatic system has a central role in controlling the amount and the duration of menstrual bleeding, thus abnormally prolonged or profuse bleeding does occur in most women affected by bleeding disorders. Whereas irregular, pre-menarchal or post-menopausal uterine bleeding is unusual in inherited or acquired haemorrhagic disorders, severe acute bleeding and heavy menstrual bleeding at menarche and chronic heavy menstrual bleeding during the entire reproductive life are common. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine the efficacy and safety of non-surgical interventions versus each other, placebo or no treatment for reducing menstrual blood loss in women with bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Haemoglobinopathies Trials Register (25 August 2016), Embase (May 2013), LILACS (February 2013) and the WHO International Clinical Trial registry (February 2013).

SELECTION CRITERIA

Randomised controlled studies of non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women of reproductive age suffering from a congenital or acquired bleeding disorder.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion, extracted data and assessed the risk of bias.

MAIN RESULTS

Three cross-over studies, with 175 women were included in the review. All three studies had an unclear risk of bias with regards to trial design and overall, the quality of evidence generated was judged to be poor.Two of the studies (n = 59) compared desmopressin (1-deamino-8-D-arginine vasopressin) with placebo. Menstrual blood loss was the primary outcome for both of these studies. Neither study found clear evidence of a difference between groups. The first of these reported a mean difference in menstrual blood loss in the desmopressin versus placebo group of 21.20 mL (95% confidence interval -19.00 to 61.50)The second study reported that even though there was an improvement of pictorial bleeding assessment chart scores with desmopressin and placebo when compared to pretreatment assessment, there was no clear evidence of difference in these scores when the two were compared to each other (results presented graphically, P = 0.51). The data from these studies could not be combined.The third study (n = 116) compared desmopressin with tranexamic acid (n = 116). This study found a decrease in pictorial bleeding assessment chart scores after both treatments as compared to baseline. The decrease in these scores was greater for tranexamic acid than for desmopressin, with a mean difference of 41.6 mL (95% confidence interval 19.6 to 63) (P < 0.0002).In relation to adverse events, across two studies, there was no clear evidence of a difference when placebo was compared to desmopressin, risk ratio 1.17 (95% confidence interval 0.41 to 3.34) . The same was also true when desmopressin was compared to tranexamic acid, risk ratio 1.17 (95% confidence interval 0.41 to 3.34).Only the study that compared desmopressin to tranexamic acid assessed quality of life. However, we are unable to present any data from this study, since no differences in this outcome between the two intervention groups were reported.

AUTHORS' CONCLUSIONS

Evidence from randomised controlled studies on the effect of desmopressin when compared to placebo in reducing menstrual blood loss is very limited and inconclusive. Two studies, each with a very limited number of participants, have shown uncertain effects in menstrual blood loss and adverse effects. A non-randomised comparison in one of the studies points to the value of combining desmopressin and tranexamic acid, which needs to be tested in a formal randomised controlled study comparison.When tranexamic acid was compared to desmopressin, a single study showed a reduction in menstrual blood loss with tranexamic acid use compared to desmopressin.There is a need to evaluate non-surgical methods for treating of menorrhagia in women with bleeding disorders through randomised controlled studies. Such methods would be more acceptable than surgery for women wishing to retain their fertility. Given that women may need to use these treatments throughout their entire reproductive life, long-term side-effects should be evaluated.

Non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women with bleeding disorders

BACKGROUND

Heavy menstrual bleeding without an organic lesion is mainly due to an imbalance of the various hormones which have a regulatory effect on the menstrual cycle. Another cause of heavy menstrual bleeding with no pelvic pathology, is the presence of an acquired or inherited bleeding disorder. The haemostatic system has a central role in controlling the amount and the duration of menstrual bleeding, thus abnormally prolonged or profuse bleeding does occur in most women affected by bleeding disorders. Whereas irregular, pre-menarchal or post-menopausal uterine bleeding is unusual in inherited or acquired haemorrhagic disorders, severe acute bleeding and heavy menstrual bleeding at menarche and chronic heavy menstrual bleeding during the entire reproductive life are common.

OBJECTIVES

To determine the efficacy and safety of non-surgical interventions versus each other, placebo or no treatment for reducing menstrual blood loss in women with bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Haemoglobinopathies Trials Register (13 March 2014), Embase (May 2013), LILACS (February 2013) and the WHO International Clinical Trial registry (February 2013).

SELECTION CRITERIA

Randomised controlled studies of non-surgical interventions for treating heavy menstrual bleeding (menorrhagia) in women of reproductive age suffering from a congenital or acquired bleeding disorder.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion, extracted data and assessed the risk of bias.

MAIN RESULTS

Three cross-over studies, with 175 participants were included in the review. All three studies had an unclear risk of bias with regards to trial design and overall, the quality of evidence generated was judged to be poor.Two of the studies (n = 59) compared desmopressin (1-deamino-8-D-arginine vasopressin) with placebo. Menstrual blood loss was the primary outcome for both of these studies. Neither study found clear evidence of a difference between groups. The first of these reported a mean difference in menstrual blood loss in the desmopressin versus placebo group of 21.20 mL (95% confidence interval -19.00 to 61.50)The second study reported that even though there was an improvement of pictorial bleeding assessment chart scores with desmopressin and placebo when compared to pretreatment assessment, there was no clear evidence of difference in these scores when the two were compared to each other (results presented graphically, P = 0.51). The data from these studies could not be combined.The third study (n = 116) compared desmopressin with tranexamic acid (n = 116). This study found a decrease in pictorial bleeding assessment chart scores after both treatments as compared to baseline. The decrease in these scores was greater for tranexamic acid than for desmopressin, with a mean difference of 41.6 mL (95% confidence interval 19.6 to 63) (P < 0.0002).In relation to adverse events, across two studies, there was no clear evidence of a difference when placebo was compared to desmopressin, risk ratio 1.17 (95% confidence interval 0.41 to 3.34) . The same was also true when desmopressin was compared to tranexamic acid, risk ratio 1.17 (95% confidence interval 0.41 to 3.34).Only the study that compared desmopressin to tranexamic acid assessed quality of life. However, we are unable to present any data from this study, since no differences in this outcome between the two intervention groups were reported.

AUTHORS' CONCLUSIONS

Evidence from randomised controlled studies on the effect of desmopressin when compared to placebo in reducing menstrual blood loss is very limited and inconclusive. Two studies, each with a very limited number of participants, have shown uncertain effects in menstrual blood loss and adverse effects. A non-randomised comparison in one of the studies points to the value of combining desmopressin and tranexamic acid, which needs to be tested in a formal randomised controlled study comparison.When tranexamic acid was compared to desmopressin, a single study showed a reduction in menstrual blood loss with tranexamic acid use compared to desmopressin.There is a need to evaluate non-surgical methods for treating of menorrhagia in women with bleeding disorders through randomised controlled studies. Such methods would be more acceptable than surgery for women wishing to retain their fertility. Given that women may need to use these treatments throughout their entire reproductive life, long-term side-effects should be evaluated.

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

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.

Why is my patient bleeding or bruising?

The evaluation of a patient presenting with bleeding symptoms is challenging. Bleeding symptoms are frequently reported by a normal population, and overlap significantly with bleeding disorders, such as type 1 Von Willebrand disease. The history is subjective; bleeding assessment tools significantly facilitate an accurate quantification of bleeding severity. The differential diagnosis is broad, ranging from defects in primary hemostasis, coagulation deficiencies, to connective tissue disorders. Finally, despite significant clinical evidence of abnormal bleeding, many patients will have not an identifiable disorder. Clinical management of bleeding disorders is highly individualized and focuses on the particular symptoms experienced by the patient.

Acquired hemophilia: a rare but life-threatening potential cause of bleeding in the intensive care unit

OBJECTIVE

There are a number of potential etiologies of severe bleeding encountered in the intensive care unit. Although rare, acquired hemophilia is one such etiology that often presents with major bleeding requiring intensive care. Despite the introduction of effective treatments, the reported mortality rate of patients with acquired hemophilia ranges from 6 to 8% and is in part attributable to sequential delays in diagnosis and appropriate treatment. The purpose of this review is to familiarize the intensive care specialist with this underrecognized cause of bleeding, with an emphasis on diagnosis and treatment.

METHODS

As the objective of this article was to provide a concise overview of the diagnosis and management of acquired hemophilia, a directed search of English-language literature was undertaken using the PubMed database, targeting such topics as the differential diagnosis of bleeding in the intensive care unit and the epidemiology, diagnosis, and treatment of acquired hemophilia. Clinical study findings pertaining to the efficacy of specific treatments for acquired hemophilia were summarized.

RESULTS AND CONCLUSION

Recognition of acquired hemophilia presents a clinical challenge, given the rarity of this condition, a general lack of familiarity with acquired hemophilia, and the potential for confusion with other more common causes of bleeding in the intensive care unit. Nevertheless, there are sentinel clinical and laboratory findings that should raise suspicion of this diagnosis. The treatment of acquired hemophilia is a multi-step, physiologically focused process aimed at controlling both active and recurrent bleeding. Therefore, prompt diagnosis is central to prognosis. Consultation with a hematologist may facilitate efficient diagnosis and management.

Acquired Platelet Dysfunction in 109 Patients From a Tertiary Care Referral Hospital

Background: Acquired platelet function defects (PFDs) remain poorly characterized, underrecognized, and therefore understudied. Patients/Methods: Clinical and laboratory records of 109 patients with acquired PFDs diagnosed over 5 years were analyzed. Screening studies (platelet count, prothrombin time, activated partial thromboplastin time, and thrombin time), template bleeding time, platelet factor 3 (PF-3) availability test, light-transmission aggregometry, and further testing as indicated were performed. Results: 64 patients had mild and 26 had major bleeding. In all, 15 were referred for preoperative testing, whereas 4 had thrombotic events. Causes and associations of PFDs were drug-induced (34), idiopathic (34), hematopoietic neoplasms (15; myeloma 4, Waldenstrom macroglobulinemia 2, chronic myeloid leukemia 4, essential thrombocythaemia 3, and primary myelofibrosis and chronic lymphocytic leukemia 1 each), chronic liver disease (4), postcardiac surgery (2), uremia (2), and thalassemia major (7). Miscellaneous disorders comprised the rest. Conclusions: Acquired PFDs span a wide range of disease settings. Systematic, sequential laboratory testing identifies patterns of dysfunction, excludes inherited disorders, and streamlines management.

Leptospirosis-associated disturbances of blood vessels, lungs and hemostasis

The frequency of massive pulmonary hemorrhages seems to be increasing in different geographic areas; however, there is no clear explanation for this trend. Although data on the pathogenesis of such complications are scarce, recent research indicates a potential role of autoimmunity and/or multifactorial mechanisms. However, much information is already available on the disturbance of hemostasis and blood vessels in leptospirosis-related literature, even if some contradictory concepts coexist. The purpose of this review is to integrate both new and classical information from human and animal studies on severe pulmonary forms of leptospirosis and disorders of hemostasis and blood vessels. We propose that the involvement of blood vessels in leptospirosis must be understood as a sepsis-like, diffuse process of endothelial activation/damage rather than as a classical systemic vasculitis. Pulmonary hemorrhages are most likely multifactorial and there has recently been evidence against the role of autoimmunity; however, further investigation of strain variations, exposure to hydrocarbons and association with renal dysfunction is required. Thrombocytopenia is a consistent feature of leptospirosis but it is not clear whether it is attributable to sepsis-related mechanisms. In addition, further investigation is required to define whether platelet function is activated or inhibited during severe leptospirosis.

Gastrointestinal plasmacytoma presenting as gastrointestinal bleeding

Clinical manifestations of gastrointestinal (GI) involvement in multiple myeloma (MM) are uncommon. We report a case of plasmacytoma presenting as upper GI bleeding in a patient with a known diagnosis of MM. Gastrointestinal bleeding persists despite aggressive medical and endoscopic treatment. The aim of our report is to heighten the awareness of plasmacytoma as an etiology of GI bleeding in patients with MM. Abnormal hemostasis, specifically the imbalance in function of all major components of the coagulation cascade, increasing bleeding risk in patients with MM, is also discussed.

Use of Recombinant Factor VIIa in Inherited and Acquired von Willebrand Disease

Recombinant factor VIIa (rFVIIa) is increasingly used outside the labeled indications for the treatment of life-threatening bleeding episodes after failure of respective standard therapy. In this article, the authors focus on the use of the agent in patients with inherited or acquired von Willebrand disease (vWD). Although the current experience is sparse, published cases indicate the high efficacy of rFVIIa for the treatment of patients refractory to conventional treatment. The agent may be used in patients with congenital vWD complicated by alloantibodies directed against substituted von Willebrand factor or in the presence of concomitant hemostatic defects as well as acquired vWD with hitherto limited therapeutic options. Controlled clinical studies are necessary to define the use of rFVIIa in this clinical setting.

Inherited platelet function disorders versus other inherited bleeding disorders: an Indian overview

Inherited deficiencies of plasma proteins involved in blood coagulation generally lead to lifelong bleeding disorders, whose severity is directly proportional to the degree of factor deficiency. Platelet and other coagulation factors play an important role in the haemostasis mechanism. We attempted to study the prevalence of inherited platelet function disorders (PFDs) and correlate with other coagulation factor disorders in the Indian population. Patients with PFDs and other coagulation factor disorders who presented at our hospital during the 5 year period (from January, 2001 to December, 2005) were the subjects of the study. A total of 1576 patients were diagnosed to have congenital bleeding disorders including PFDs, von Willebrand disease, haemophilia A and B and rare coagulation disorder cases. Haemophilia A (HA) was the most common and was seen in 52.31% of the patients followed by total PFDs seen in 27.77% of the patients. Based on severity of the disease, the results of PFDs were highly significant when compared to haemophilia and von Willebrand disease (VWD) (p=0.000). Severity was found higher in HA (77.8%) followed by HB (69.6%) and was found lower for PF3 availability defect (9.0%). It has been concluded that the prevalence of PFDs is relatively low as compared to coagulation factors related disorder and also it has been established that type-1 VWD is relatively less frequent in India as compared to the West.

Perioperative fluid management in renal transplantation: a narrative review of the literature

Adequate volume maintenance is essential to prevent acute renal failure during major surgery or to ensure graft function after renal transplantation. The various recommendations on the optimum fluid therapy are based, at best, on sparse evidence only from observational studies. This article reviews the literature on perioperative fluid management in renal transplantation. Crystalloid solutions not exerting any specific side-effects are the first choice for volume replacement in kidney transplantation. The use of colloids should be restricted to patients with severe intravascular volume deficits necessitating high volume restoration. The routine application of albumin, dopamine, and high dose diuretics is no longer warranted. Mannitol given immediately before removal of the vessel clamps reduces the requirement of post-transplant dialysis, but has no effects on graft function in the long term. There is insufficient evidence on the best use of dialysis, but it seems peritoneal dialysis pretransplant is associated with less delayed graft function, whereas the preference of dialysis post-transplant is not yet well-founded. This review article should provide better guidance for fluid management in kidney transplantation until best-evidence guidelines can be established based upon more research.

Conformational stability and domain unfolding of the Von Willebrand factor A domains

Von Willebrand factor (VWF), a multimeric multidomain glycoprotein secreted into the blood from vascular endothelial cells, initiates platelet adhesion at sites of vascular injury. This process requires the binding of platelet glycoprotein Ib-IX-V to the A1 domain of VWF monomeric subunits under fluid shear stress. The A2 domain of VWF monomers contains a proteolytic site specific for a circulating plasma VWF metalloprotease, A Disintegrin and Metalloprotease with Thrombospondin motifs, member #13 of the ADAMTS enzyme family (ADAMTS-13), that functions to reduce adhesiveness of newly released, unusually large (UL), hyperactive forms of VWF. Shear stress assists ADAMTS-13 proteolysis of ULVWF multimers allowing ADAMTS-13 cleavage of an exposed peptide bond in the A2 domain. Shear stress may induce conformational changes in VWF, and even unfold regions of VWF monomeric subunits. We used urea as a surrogate for shear to study denaturation of the individual VWF recombinant A domains, A1, A2, and A3, and the domain triplet, A1-A2-A3. Denaturation was evaluated as a function of the urea concentration, and the intrinsic thermodynamic stability of the domains against unfolding was determined. The A1 domain unfolded in a 3-state manner through a stable intermediate. Domains A2 and A3 unfolded in a 2-state manner from native to denatured. The A1-A2-A3 triple domain unfolded in a 6-state manner through four partially folded intermediates between the native and denatured states. Urea denaturation of A1-A2-A3 was characterized by two major unfolding transitions: the first corresponding to the simultaneous complete unfolding of A2 and partial unfolding of A1 to the intermediate state; and the second corresponding to the complete unfolding of A3 followed by gradual unfolding of the intermediate state of A1 at high urea concentration. The A2 domain containing the cleavage site for ADAMTS-13 was the least stable of the three domains and was the most susceptible to unfolding. The low stability of the A2 domain is likely to be important in regulating the exposure of the A2 domain cleavage site in response to shear stress, ULVWF platelet adherence, and the attachment of ADAMTS-13 to ULVWF.