Beyond the platelet count: immature platelet fraction and thromboelastometry correlate with bleeding in patients with immune thrombocytopenia

Early Goal-Directed Hemostatic Therapy for Severe Acute Bleeding Management in the Intensive Care Unit: A Narrative Review

This is a narrative review of the published evidence for bleeding management in critically ill patients in different clinical settings in the intensive care unit (ICU). We aimed to describe "The Ten Steps" approach to early goal-directed hemostatic therapy (EGDHT) using point-of-care testing (POCT), coagulation factor concentrates, and hemostatic drugs, according to the individual needs of each patient. We searched National Library of Medicine, MEDLINE for publications relevant to management of critical ill bleeding patients in different settings in the ICU. Bibliographies of included articles were also searched to identify additional relevant studies. English-language systematic reviews, meta-analyses, randomized trials, observational studies, and case reports were reviewed. Data related to study methodology, patient population, bleeding management strategy, and clinical outcomes were qualitatively evaluated. According to systematic reviews and meta-analyses, EGDHT guided by viscoelastic testing (VET) has been associated with a reduction in transfusion utilization, improved morbidity and outcome in patients with active bleeding. Furthermore, literature data showed an increased risk of severe adverse events and poor clinical outcomes with inappropriate prophylactic uses of blood components to correct altered conventional coagulation tests (CCTs). Finally, prospective, randomized, controlled trials point to the role of goal-directed fibrinogen substitution to reduce bleeding and the amount of red blood cell (RBC) transfusion with the potential to decrease mortality. In conclusion, severe acute bleeding management in the ICU is still a major challenge for intensive care physicians. The organized and sequential approach to the bleeding patient, guided by POCT allows for rapid and effective bleeding control, through the rational use of blood components and hemostatic drugs, since VET can identify specific coagulation disorders in real time, guiding hemostatic therapy with coagulation factor concentrates and hemostatic drugs with individual goals.

Addressing thrombosis concerns in immune thrombocytopenia: the role of fostamatinib in immune thrombocytopenia management

INTRODUCTION

Immune thrombocytopenia (ITP), a disease that commonly presents with an increased risk of bleeding, can also paradoxically produce an increased risk of thromboembolic events. The risk of thromboembolism can be associated with patient-related factors (e.g. co-morbidities, age and history of thrombosis), disease-related factors (e.g. a greater proportion of younger, more reactive platelets, and the presence of microparticles and pro-inflammatory cytokines) and treatment-related factors (e.g. splenectomy, thrombopoietin receptor agonists, and IVIg).

AREAS COVERED

Aspects of the pathophysiology of ITP and the effects of treatment are discussed with emphasis on individualizing treatment based on the patient's thromboembolic risk, treatment options and preferences.

EXPERT OPINION

An increased understanding of the pathophysiology of ITP has led to the development of new agents such as fostamatinib, a spleen tyrosine kinase inhibitor. Further research into the factors contributing to the risks for bleeding and thromboembolic events can contribute to the development of more specific therapies for ITP and allow greater individualization of therapy based on each patient's medical history and clinical status.

A bibliometric analysis of primary immune thrombocytopenia from 2011 to 2021

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia. This bibliometric analysis was applied to identify the characteristics of global scientific output, the hotspots, and frontiers of ITP over the past 10 years. We retrieved publications from 2011 to 2021 from the Web of Science Core Collection (WoSCC). Bibliometrix package, VOSviewer, and Citespace were used to analyse and visualize the trend, distribution, and hotspots of research on ITP. Altogether, there were 2084 papers, written by 9080 authors from 410 organizations in 70 countries/regions, published in 456 journals with 37 160 co-cited references. In the last decades, the most productive journal was British Journal of Haematology, China was the most productive country. and the most cited journal was Blood. Shandong University was the most productive institution in the field of ITP. NEUNERT C, 2011, BLOOD, CHENG G, 2011, LANCET, and PATEL VL, 2012, BLOOD were the top three most cited documents. "Thrombopoietin receptor agonist", "regulatory T cell" and "sialic acid" were three hotspots of the last decade. And "immature platelet fraction", "Th17", and "fostamatinib" would be research frontiers in the feature. The present study provided a novel insight for future research directions and scientific decision-making.

Anticoagulation in thrombocytopenic patients - Time to rethink?

One of the difficult clinical situations in the anticoagulation era is how to give these medications to patients with significantly reduced platelet counts. The concern is the heightened bleeding risk, and the current practice is to apply a certain platelet count threshold below which the use of anticoagulant is deemed unsafe. However, this is not an evidence-based approach especially because the thresholds arose from studies in patients with acute leukemia. In this forum article, we discuss the bleeding risk estimation in thrombocytopenic patients when the decreased counts may not be related to marrow underproduction and aim to identify possible markers which can help in this risk estimation beyond platelet counts. We exhort future studies to include a combination of these markers, which may then guide us to administer safe anticoagulation in patients with severe thrombocytopenia.

Flow cytometry for evaluating platelet immunophenotyping and function in patients with thrombocytopenia

Platelets play an essential role in primary hemostasis through bleeding and thromboembolism. Thus, the diagnosis or evaluation of impaired hereditary, acquired, and drug-related platelet dysfunction has become imperative. The assessment of the platelet function is too complex for routine platelet function study. The major methods involved in platelet function study include platelet function analyzer testing, thromboelastography, thromboelastometry, light transmission aggregometry, and flow cytometry. The current review article focuses on the methods with flow cytometry for immunophenotyping of platelet and evaluating platelet function for platelet disorders, especially in patients with thrombocytopenia. According to the consensus published by the International Society on Thrombosis and Haemostasis, for inherited and acquired platelet disorders, the two major measures by which flow cytometry determines platelet function are glycoprotein IIb/IIIa/P-selectin (CD62p) expression and percentage of leukocyte-platelet aggregates. Using flow cytometry to determine platelet function has several advantages, including good sensitivity to low platelet counts, small blood volume required, and the nonnecessity of centrifugation. However, flow cytometry has still many limitations and challenges, with standardization for routine laboratory testing also proving difficult. Although flow cytometry is available for multipurpose and sensitive study of platelet functions at the same time, the challenging analysis gradually increases and needs to be addressed before reality.

Viscoelastic testing in benign hematologic disorders: Clinical perspectives and future implications of point-of-care testing to assess hemostatic competence

Viscoelastic tests (VETs) have been used routinely for liver transplantation, cardiac surgery, and trauma, but only recently have found clinical utility in benign hematologic disorders. Therefore, guidelines for diagnosis and treatment of these disorders based on viscoelastic variables have been adapted from the existing transplant, cardiothoracic surgery, and trauma resuscitation literature. As a result, diagnostic and therapeutic strategies for benign hematologic disorders utilizing VETs are not uniform. Accordingly, even though there has been a recent increase in the utilization of VET for the diagnosis and treatment of such disorders, the literature is still in its early stages. Analysis of point-of-care viscoelastic tracings from benign hematologic disorders has the potential to allow prompt recognition of disease and to guide patient-specific intervention. Here we present a review describing the application of VETs to benign hematologic disorders.

Immature platelet levels correlate with disease activity and predict treatment response of thrombocytopenia in lupus patients

OBJECTIVE

The immature platelet fraction (IPF) represents recently produced platelets in bone marrow and this parameter is increased in patient with primary immune thrombocytopenia (ITP). We investigated the associations between IPF and absolute immature platelet count (AIPC), and clinical parameters in systemic lupus erythematosus (SLE), which has more complex pathological mechanisms than in primary ITP.

METHODS

Patients with SLE were retrospectively reviewed at the University of Tokyo Hospital from May, 2012 to January, 2021. The correlations between clinical parameters and the number of immature platelets were assessed with Spearman's rank correlation coefficients. A multiple logistic regression model was used to identify the independent clinical parameters for IPF and AIPC. The difference in the distribution of time for a complete response (CR) after prednisolone (PSL) administration was also evaluated by log-rank test.

RESULTS

A total of 282 SLE patients were enrolled, and 12.41% of those patients showed thrombocytopenia. IPF correlated with clinical parameters such as platelet count (r = -0.58), AIPC (r = 0.64) and systemic lupus erythematosus disease activity index 2000 (SLEDAI-2K) (r = 0.24). SLEDAI-2K [odds ratio (OR) (per unit increase), 1.07; 95% CI, 1.013 - 1.13] and thrombocytopenia (OR, 32.23; 95% CI, 11.072 - 93.80) were independent clinical parameters to account for IPF increase. IPF correlated with the number of bone marrow megakaryocytes (n = 19, r = 0.57). Notably, the probability of CR in response to PSL in AIPC-high patients was higher than in AIPC-low patients (hazard ratio, 4.62; 95% CI, 1.07 - 20.02).

CONCLUSION

IPF correlated with disease activity of SLE and represented platelet production in the bone marrow, whereas AIPC predicted a rapid response to steroids in thrombocytopenic patients with SLE.

Platelet number and function in response to a single intravenous dose of vincristine

Background

Vincristine might increase circulating platelet numbers but the functional capacity of these newly released platelets is unknown.

Objective

To evaluate and compare the functionality of mature and immature (reticulated) platelets after a single intravenous dose of vincristine in dogs.

Animals

Ten healthy purpose‐bred dogs.

Methods

Dogs prospectively received a single IV injection of 0.02 mg/kg vincristine or 0.9% saline. Before and after treatment on days 3, 5, and 7, platelets (resting and after thrombin stimulation) were assessed by flow cytometric determination of P‐selectin (CD62P) expression. Reticulated platelets were distinguished using thiazole orange (TO) staining.

Results

Relative to saline, vincristine administration increased platelet count from day 0 to day 7 (225 ± 58 to 273 ± 65 × 10³/μL, vs 299 ± 76.4 to 214 ± 20 × 10³/μL, P = .01) and increased percentage of reticulated platelets from day 0 to day 5 (3.9 ± 1.5% to 6.1 ± 1.6%, P = .02). On all days, reticulated platelets had greater resting expression of CD62P than did mature platelets (49.6 ± 4% vs 10.2 ± 1%, P ≤ .001). Across all days, CD62P expression by reticulated platelets in the vincristine and saline‐treated groups was not different when unstimulated (P = .7) or after thrombin stimulation (P = .33).

Conclusions and Clinical Importance

Reticulated platelets released in response to vincristine administration function similarly to mature platelets.

Platelet function and bleeding at different phases of childhood immune thrombocytopenia

Immune thrombocytopenia (ITP) is believed to be associated with platelet function defects. However, their mechanisms are poorly understood, in particular with regard to differences between ITP phases, patient age, and therapy. We investigated platelet function and bleeding in children with either persistent or chronic ITP, with or without romiplostim therapy. The study included 151 children with ITP, of whom 56 had disease duration less than 12 months (grouped together as acute/persistent) and 95 were chronic. Samples of 57 healthy children were used as controls, while 5 patients with leukemia, 5 with aplastic anemia, 4 with MYH9-associated thrombocytopenia, and 7 with Wiskott-Aldrich syndrome were used as non-ITP thrombocytopenia controls. Whole blood flow cytometry revealed that platelets in both acute/persistent and chronic ITP were increased in size compared with healthy donors. They were also pre-activated as assessed by PAC1, CD62p, cytosolic calcium, and procoagulant platelet levels. This pattern was not observed in other childhood thrombocytopenias. Pre-activation by CD62p was higher in the bleeding group in the chronic ITP cohort only. Romiplostim treatment decreased size and pre-activation of the patient platelets, but not calcium. Our data suggest that increased size, pre-activation, and cytosolic calcium are common for all ITP platelets, but their association with bleeding could depend on the disease phase.

Thrombosis in immune thrombocytopenia - current status and future perspectives

Immune thrombocytopenia (ITP) is an autoimmune disorder in which a combination of defective platelet production and enhanced clearance leads to thrombocytopenia. The primary aim for therapy in patients with this condition is the prevention of bleeding. However, more recently, increased rates of venous and arterial thrombotic events have been reported in ITP, even in the context of marked thrombocytopenia. In this review we discuss the epidemiology, aetiology and management of thrombotic events in these patients. We consider the impact of ITP therapies on the increased thrombotic risk, in particular the use of thrombopoietin-receptor agonists (TPO-RAs), as well as factors inherent to ITP itself. We also discuss the limited evidence available to guide clinicians in the treatment of these complex cases.

Platelet Phenotyping and Function Testing in Thrombocytopenia

Patients who suffer from inherited or acquired thrombocytopenia can be also affected by platelet function defects, which potentially increase the risk of severe and life-threatening bleeding complications. A plethora of tests and assays for platelet phenotyping and function analysis are available, which are, in part, feasible in clinical practice due to adequate point-of-care qualities. However, most of them are time-consuming, require experienced and skilled personnel for platelet handling and processing, and are therefore well-established only in specialized laboratories. This review summarizes major indications, methods/assays for platelet phenotyping, and in vitro function testing in blood samples with reduced platelet count in relation to their clinical practicability. In addition, the diagnostic significance, difficulties, and challenges of selected tests to evaluate the hemostatic capacity and specific defects of platelets with reduced number are addressed.

Thromboelastometry-guided neuraxial anesthesia in a parturient with severe thrombocytopenia due to large granular lymphocytic leukemia

Severe thrombocytopenia (platelet count <50 000/μl) in pregnancy is uncommon and is generally considered a contraindication to neuraxial anesthesia. We present a case of a parturient who presented with severe thrombocytopenia secondary to bone marrow failure. After receiving platelet and cryoprecipitate transfusions to correct coagulopathy as verified by thromboelastometry, neuraxial anesthesia was safely utilized.

Immature Platelet Dynamics in Immune-Mediated Thrombocytopenic States

A major challenge encountered by clinicians is differentiating presentations characterized by significant thrombocytopenia due to overlapping clinical symptoms and signs in the setting of ambiguous laboratory results. Immature platelets represent the youngest platelets that can be measured in peripheral blood by current hematology analyzers. These young platelets are larger, with higher RNA content recently released from the bone marrow. Thrombocytopenic presentations caused directly or indirectly by immune responses can lead to compensatory bone marrow responses seeking to normalize the platelet count; thus obtaining absolute immature platelet counts may be informative while triaging patients. Over the last decade, their use has expanded beyond being an early biomarker of bone marrow reconstitution post-hematopoietic stem cell transplantation to being used to establish bone marrow responses to infection and thrombocytopenias due to immune etiologies. Its accessibility as part of more detailed platelet indices obtained with routine laboratories makes it a promising option to understand the bone marrow's real-time response to disease states characterized by thrombocytopenia. This review will look at the immature platelet count as a biomarker, while presenting current attempts trying to understand how it could be used in thrombocytopenias occurring secondary to a given immune etiology.

Immature platelet dynamics correlate with ADAMTS13 deficiency and predict therapy response in immune-mediated thrombotic thrombocytopenic purpura

INTRODUCTION

Thrombotic thrombocytopenic purpura (TTP) requires prompt initiation of therapeutic plasma exchange (TPE) to avoid significant morbidity and mortality. ADAMTS13 activity testing defines TTP, however, at most institutions this is a send-out test and therapy is often initiated prior to measurement availability. We describe our experience looking at absolute immature platelet counts (A-IPC) in patients suspected with TTP at presentation and in response to therapy.

MATERIALS AND METHODS

Forty-eight patients treated for suspected TTP with A-IPC measure on admission and during hospitalization met inclusion criteria. Of these patients, sixteen had new-onset TTP (ADAMTS13 < 10%), ten were relapsing patients (first diagnosis prior to study period), and 22 were classified as non-TTP (ADAMTS13 ≥ 10%).

RESULTS

Patients with ADAMTS13 deficiency (TTP) had A-IPC different from those without deficiency. A-IPC of 1-2 × 10⁹/L at presentation had high sensitivity and specificity with a negative predictive value of 95.5 to 100%. Two-to-three-fold increases in A-IPC from count prior to TPE initiation was limited to ADAMTS13 deficient patients who was the group responding to therapy. Increases were higher in patients with new disease onset compared to relapsing patients (p = 0.018). Likewise, relapsing patients' A-IPC appeared dependent upon platelet count at time of relapse. A-IPC predicted and correlated with ADAMTS13 deficiency in new-onset TTP (p = 0.0002).

CONCLUSIONS

Only patients with A-IPC-fold increases responded to TPE with platelet count normalization. Our results represent a proof of concept that A-IPC measurements can supplement ADAMTS13 testing and determine response to TPE. Future studies are needed to establish ways to apply these findings in the setting of suspected TTP.

Absolute Immature Platelet Counts Suggest Platelet Production Suppression during Complicated Relapsing Thrombotic Thrombocytopenic Purpura

Absolute immature platelet counts (A-IPC) aid in diagnosis and treatment follow-up in thrombotic thrombocytopenic purpura (TTP). A-IPC was used to follow a patient on mycophenolate mofetil (MMF) maintenance therapy treated with a prolonged therapeutic plasma exchange (TPE) regimen for relapsing TTP. On admission, the platelet (PLT) count was 95 × 109/L declining to 14 × 109/L in 5 days. Daily TPE was initiated for suspected TTP, and MMF was discontinued. A-IPC and PLT count were 1 × 109/L and 14 × 109/L, respectively, prior to first TPE. A-IPC improved to 3.2 × 109/L with 1 TPE, and on day 5, A-IPC and PLT count were 7.5 × 109/L and 218 × 109/L, respectively. On day 6, A-IPC and PLT count decreased to 4.8 × 109/L and 132 × 109/L further worsening to 0.4 × 109/L and 13 × 109/L, respectively. ADAMTS13 activity remained <5% with an inhibitor; counts did not recover. Initial improvement followed by rapidly declining A-IPC despite therapy suggested production suppression. In TTP, A-IPC may aid in establishing early therapy effects over PLT production.

The role of ROTEM variables based on clot elasticity and platelet component in predicting bleeding risk in thrombocytopenic critically ill neonates

BACKGROUND

Our aim was to investigate the role of thromboelastometry (ROTEM) parameters, including maximum clot elasticity (MCE) and platelet component (PLTEM MCE and PLTEM MCF), in early prediction of bleeding events in thrombocytopenic critically ill neonates.

MATERIAL AND METHODS

This single-center, prospective cohort study included 110 consecutive thrombocytopenic neonates with sepsis, suspected sepsis, or hypoxia. On the first day of disease onset, ROTEM EXTEM and FIBTEM assays were performed and the neonatal bleeding assessment tool was used for the evaluation of bleeding events.

RESULTS

Most EXTEM and FIBTEM ROTEM parameters significantly differed between neonates with (n = 77) and without bleeding events (n = 33). Neonates with bleeding events had significantly lower PLTEM MCE and PLTEM MCF values compared to those without bleeding events (P < .001). Platelet count was found to be strongly positively correlated with EXTEM A5 (Spearman's rho = 0.61, P < .001) and A10 (rho = 0.64, P < .001). EXTEM A10 demonstrated the best prognostic performance (AUC = 0.853) with an optimal cutoff value (≤37 mm) (sensitivity = 91%, specificity = 76%) for prediction of bleeding events in thrombocytopenic neonates.

CONCLUSIONS

EXTEM A5 and EXTEM A10 were found to be strong predictors of hemorrhage, compared to most ROTEM variables quantifying clot elasticity and platelet component in thrombocytopenic critically ill neonates.

The role of platelets in bleeding in patients with thrombocytopenia and hematological disease

This review evaluates the role of platelets in bleeding risk among patients with hematological disease and thrombocytopenia. Platelets are pivotal in primary hemostasis, and possess non-hemostatic properties involved in angiogenesis, tissue repair, inflammation and metastatis. Also, platelets safeguard vascular integrity in inflamed vessels. Overall, bleeding risk depends on the underlying disease, and patients with cancer and platelet count <6-10 × 109/L have a markedly increased bleeding risk, while the platelet count does not correlate with bleeding risk at higher platelet counts. Other factors might affect platelet properties and thus bleeding risk, for example, drugs, low hematocrit, coagulation system impairments or transfusion of dysfunctional donor platelets. For patients with leukemia and immune thrombocytopenia, reduced platelet activation, platelet aggregation, or thrombopoiesis, reflected by the reduced presence of reticulated platelets, are associated with bleeding phenotype. However, mechanistic insight into the cause of reduced platelet function in different thrombocytopenic conditions is sparse, except for some inherited platelet disorders. Promising tools for platelet function studies in thrombocytopenia are flow cytometry and biomarker studies on platelet constituents. An important message from this current paper is that bleeding risk assessment must be tailored to specific patient populations and cannot be applied broadly to all patients with thrombocytopenia.

Systematic review of viscoelastic testing (TEG/ROTEM) in obstetrics and recommendations from the women's SSC of the ISTH

Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are point-of-care viscoelastic devices that use whole blood samples to assess coagulation and fibrinolysis. These devices have been studied extensively in cardiac surgery, but there is limited robust evidence supporting its use in obstetrics. The hesitancy toward its routine use in obstetrics may be due to the current lack of randomized controlled trials and large observational studies. The study aims to systematically review studies that investigated TEG/ROTEM use in pregnancy or peripartum, and to provide recommendations for future studies to fill current research gaps. We performed a systematic review of studies on viscoelastic testing in obstetrics. Included studies were original research, used TEG or ROTEM during pregnancy or peripartum, and published in English. Ninety-three studies, spanning 31 years from 1989 to 2020 and with a total of 32,817 participants, were included. Sixty-two (66.7%) of the studies used TEG and 31 (33.3%) used ROTEM. To date, there are a total of two randomized controlled trials on TEG/ROTEM use in obstetrics. ROTEM may be used to guide transfusion therapy for postpartum hemorrhage. TEG and ROTEM can detect the hypercoagulable changes associated with pregnancy. Variability between study protocols and results suggests the need for future large prospective high-quality studies with standardized protocols to investigate the utility of TEG/ROTEM in assessing risk for thrombosis and hemorrhage as well as in guiding prophylaxis and treatment in obstetric patients. This review identifies the gaps and provides concrete recommendations for future studies to fill those gaps.

Immature platelets: a review of the available evidence

Immature platelets or reticulated platelets are newly released thrombocytes. They can be identified by their large size and high RNA cytoplasm concentration. Immature platelet fraction (IPF) represents the percentage of immature circulative platelets to the total number of platelets. The development of analytical standardization of this hematological parameter by new automated devices allowed a better exploration of its contribution in a context of thrombocytopenia. In fact, several studies had confirmed its clinical utility to differentiate immune thrombocytopenia from other causes of thrombocytopenia. IPF can also predict platelets recovery after chemotherapy and successful engraftment. In addition, immature platelets have shown utility in other diseases such as coronary artery diseases, bacterial infections and liver diseases. Despite all these advantages, immature platelet fraction can be increased in some cases of thrombocytopenia characterized by platelets hypoproduction. The aim of this review is to present the immature platelet fraction contribution in clinical practice.

Rotational thromboelastometry parameters as predicting factors for bleeding in immune thrombocytopenic purpura

OBJECTIVE/BACKGROUND

Patients with immune thrombocytopenic purpura (ITP) often present with a severe reduction in platelet counts and suffer from an increased risk of bleeding. However, platelet counts do not accurately predict bleeding risk in these patients.

METHODS

We thereby conducted a case series prospective study to compare the ability to predict hemorrhage in ITP patients between platelet counts and various rotational thromboelastometry (ROTEM) parameters.

RESULTS

The inclusion criteria for patients diagnosed with acute, persistent, and chronic ITP were platelet counts of <30 × 10⁹/L and no clinically significant bleeding (grade ≥ 2 according to the WHO Bleeding Scale) at the beginning of the study. After 24 hours of follow-up, of the 45 enrolled patients, 14 (31.1%) experienced clinically significant bleeding. The mean platelet counts of patients with and without clinically significant bleeding were not statistically different (p = .09). However, the mean EXTEM maximum clot firmness (MCF), EXTEM A10, EXTEM area under the curve (AUC), and platelet maximum clot elasticity (MCE) values of the two groups were statistically different (p < .05). There was also a significant difference in IPF values between these two groups (p < .05.) CONCLUSION: Results obtained from this preliminary study demonstrate that ROTEM parameters might be useful in predicting factors for hemorrhage in ITP patients. Future studies with a larger sample size is warranted to confirm our findings, which will allow prompt and effective bleeding management in ITP patients.

Platelet Counting: Ugly Traps and Good Advice. Proposals from the French-Speaking Cellular Hematology Group (GFHC)

Despite the ongoing development of automated hematology analyzers to optimize complete blood count results, platelet count still suffers from pre-analytical or analytical pitfalls, including EDTA-induced pseudothrombocytopenia. Although most of these interferences are widely known, laboratory practices remain highly heterogeneous. In order to harmonize and standardize cellular hematology practices, the French-speaking Cellular Hematology Group (GFHC) wants to focus on interferences that could affect the platelet count and to detail the verification steps with minimal recommendations, taking into account the different technologies employed nowadays. The conclusions of the GFHC presented here met with a "strong professional agreement" and are explained with their rationale to define the course of actions, in case thrombocytopenia or thrombocytosis is detected. They are proposed as minimum recommendations to be used by each specialist in laboratory medicine who remains free to use more restrictive guidelines based on the patient’s condition.

Novel scientific approaches and future research directions in understanding ITP

Diagnosis of immune thrombocytopenia (ITP) and prediction of response to therapy remain significant and constant challenges in hematology. In patients who present with ITP, the platelet count is frequently used as a surrogate marker for disease severity, and so often determines the need for therapy. Although there is a clear link between thrombocytopenia and hemostasis, a direct correlation between the extent of thrombocytopenia and bleeding symptoms, especially at lower platelet counts is lacking. Thus, bleeding in ITP is heterogeneous, unpredictable, and nearly always based on a multitude of risk factors, beyond the platelet count. The development of an evidence-based, validated risk stratification model for ITP treatment is a major goal in the ITP community and this review discusses new laboratory approaches to evaluate the various pathobiologies of ITP that may inform such a model.

Immature platelet fraction: A useful marker for identifying the cause of thrombocytopenia and predicting platelet recovery

INTRODUCTION

The assessment of bone marrow thrombopoietic activity in patients with thrombocytopenia is necessary to achieve an accurate diagnosis and administer effective treatment. We evaluated the discriminatory power of the immature platelet fraction (IPF) in differentiating hyperdestructive/consumptive thrombocytopenia from hypoproductive thrombocytopenia and its potential use as a predictive marker for platelet recovery.

METHODS

In this observational study, platelet indices, including IPF, were measured in 105 healthy individuals, 27 patients with hyperdestructive/consumptive thrombocytopenia (all with immune thrombocytopenic purpura [ITP]), and 35 patients with hypoproductive thrombocytopenia (5 with aplastic anemia and 30 with cancer who were undergoing chemotherapy) using a Sysmex XN-3000 hematology analyzer.

RESULTS

The platelet distribution width, mean platelet volume, platelet large cell ratio, IPF, and absolute immature platelet count (AIPC) were significantly higher in the hyperdestructive/consumptive thrombocytopenia group than in the hypoproductive thrombocytopenia group (P < .001). The IPF showed the highest difference between the two patient groups (200%). Receiver operating characteristics analysis that showed the IPF had the largest area under the curve among all the platelet indices analyzed; its cut-off value was 2.3%. The IPF decreased 3 to 4 days in advance of platelet count elevation in patients with ITP, whereas the delta AIPC increased 3 days in advance. Furthermore, the IPF and delta AIPC increased 5.5 days and 8.5 days, respectively, before platelet counts increased up to 130.0 × 10/L in cancer patients receiving chemotherapy.

CONCLUSION

These data demonstrated that the IPF and delta AIPC are both excellent indicators of the etiology of thrombocytopenia and predictive markers for platelet recovery.

Immune thrombocytopenia (ITP): Pathophysiology update and diagnostic dilemmas

Immune thrombocytopenia (ITP) is a common autoimmune bleeding disorder. The understanding of ITP pathogenesis is rapidly evolving. We now recognize ITP as a complex and heterogeneous syndrome that results from a combination of humoral and cell-mediated attacks on platelets peripherally and megakaryocytes in the bone marrow. Autoantibody-mediated ITP also varies in the pathway used to clear platelets, which depends on the platelet glycoprotein being targeted. Moreover, ITP patients present with variable bleeding severities and treatment responses that do not closely correlate with platelet count. A gold standard diagnostic test for ITP is lacking, and biomarkers to assess disease severity are in their infancy. This review provides an update on the immunopathogenesis of ITP and summarizes currently available tests for ITP diagnosis, prediction of disease severity, and treatment responses. Given the heterogeneous pathogenesis and clinical presentation of ITP, we highlight the need for the development of diagnostic and prognostic tests that would allow for the individualized management of a complex disease.

Correlation of rotational thromboelastometry (ROTEM) parameters with platelet count and their ability to predict thrombocytopenia in dogs

The study objectivs were to evaluate the correlation between platelet count (PLT) and rotational thromboelastometry (ROTEM) parameters and to determine ROTEM cut-off values for identification of thrombocytopenia in dogs. Medical records of 113 dogs with concurrent EXTEM (ROTEM activated by proprietary tissue factor), FIBTEM (EXTEM with added cytochalasin D) analysis and PLT were retrospectively reviewed. Signalment, treatment prior to analysis, hematocrit (HCT), EXTEM/FIBTEM maximum clot firmness (MCF_EXTEM, MCF_FIBTEM), EXTEM/FIBTEM maximum clot elasticity (MCE_EXTEM, MCE_FIBTEM) and EXTEM maximum lysis (ML_EXTEM) were extracted from patient records and ROTEM database. Delta (Δ) MCF was calculated as MCF_EXTEM-MCF_FIBTEM and ΔMCE as MCE_EXTEM-MCE_FIBTEM. The PLT was correlated to MCF_EXTEM, MCE_EXTEM, ΔMCF and ΔMCE using Spearman-Rho analysis. Correlations were further analyzed in thrombocytopenic dogs. The ability to predict thrombocytopenia was evaluated with receiver operating characteristics (ROC). Thirty-seven samples (32.7%) showed thrombocytopenia (<130 × 10⁹/L) and 19 samples (17%) severe thrombocytopenia (<60* x 10⁹/L). The PLT significantly correlated with MCF_EXTEM (r = 0.545, P < .001), MCE_EXTEM (r = 0.547, P < .001), ΔMCF (r = 0.441, P < .001) and ΔMCE (r = 0.559, P < .001). MCF_EXTEM < 49 mm, MCE_EXTEM < 93, ΔMCF <42 mm and ΔMCE <90 predicted thrombocytopenia <60 × 10⁹/L with a sensitivity of 90% and a specificity of 78% with a negative predictive value >97% for all 4 parameters. In conclusion, PLT in dogs correlated moderately but significantly with all evaluated ROTEM parameters. All parameters were able to rule out thrombocytopenia <60 × 10⁹/L with a high negative predictive value, while the sensitivity to predict thrombocytopenia was only moderate and the positive predictive value was low.

Initial management of immune thrombocytopaenia in adults based on risk stratification

Patients with immune thrombocytopaenia (ITP) have a wide spectrum of disease severity and bleeding risk even at similar platelet counts. Hence, additional clinical and laboratory factors may be considered in the evaluation of bleeding risk in ITP. Risk stratification based on predicted bleeding risk may help to identify high-risk patients and guide the initial management of ITP in adults requiring treatment. Recent evidence supports the use of high-dose dexamethasone therapy over prednisone in the initial management of ITP because of improved initial response rates, shorter median time to response and better safety profile. A risk-stratified approach to management of ITP is hoped to reduce bleeding complications in high-risk patients; however, the outcomes of such management approach need to be studied prospectively. Additionally, whether therapy intensification or combination of dual therapy such as intravenous immunoglobulin or rituximab in combination with dexamethasone can reduce bleeding complications in high-risk ITP should be studied in the future.

Risk Factors for Transfusion after Orthotopic Liver Transplantation

Background

Transfusion of blood products during orthotopic liver transplantation (OLT) is associated with increased morbidity and mortality. Although risk factors associated with intraoperative transfusion requirements have been widely assessed, published data on the prediction of postoperative transfusion requirements are sparse.

Objectives

The aim of this study was to evaluate risk factors for postoperative allogeneic transfusion requirements in OLT.

Methods

Clinical characteristics and intraoperative parameters of 645 consecutive adult patients undergoing OLT were retrospectively reviewed. Multivariate logistic regression was used to determine the main determinants for postoperative transfusion requirements.

Results

Determinants of postoperative transfusion requirements of any blood product in the postoperative period were the number of blood products transfused in the intraoperative period (OR 1.17, 95% CI 1.08-1.28), warm ischemia time (OR 1.05, 95% CI 1.02-1.08), MELD score (OR 1.05, 95% CI 1.01-1.08) and hepatocellular carcinoma (OR 0.45, 95% CI 0.28-0.72). A dose-dependent effect between the number of units transfused in the intraoperative period and transfusion requirements in the postoperative period was also observed. The relative risk of postoperative allogeneic transfusion of any blood component was 5.9 (95% CI 3.4-10.4) for patients who received 1-2 units in the intraoperative period, 7.3 (95% CI 3.6-14.7) for those who received 3-5 units in the intraoperative period, and 11.1 (95% CI 4.7-26.4) for those who received 6 or more units, when compared to no intraoperative blood transfusion.

Conclusion

Our study demonstrated an association between intraoperative transfusion and warm ischemia time with postoperative transfusion requirements. The identification of risk factors for transfusion in the postoperative period may improve management of these patients by increasing awareness to bleeding complications in this high-risk population and by expanding hemostasis monitoring to the postoperative period.

Compensatory effect of fibrinogen in a patient with bone marrow aplasia, septic shock, and severe thrombocytopenia guided by thromboelastometry: a case report

Platelet transfusion is a common practice to prevent spontaneous bleeding or bleeding due to invasive procedures. Transfusion of allogeneic blood components is associated with increased mortality and a worse clinical outcome. The clot strength is assessed by thromboelastometry and determined by the interaction between platelets and fibrinogen. The compensatory effect of high levels of fibrinogen on clot strength in patients with thrombocytopenia has been demonstrated in different clinical settings including sepsis. We report the case of a patient with severe thrombocytopenia whose thromboelastometry showed clot strength that was compensated for by the increase in plasma fibrinogen levels as an acute phase reactant of septic patients. Here, we report a case of a 62-year-old female diagnosed with bone marrow aplasia admitted in the intensive care unit with septic shock and severe thrombocytopenia. During the first 24 hours in the intensive care unit, she presented acute respiratory insufficiency and circulatory shock. The use of invasive mechanical ventilation and norepinephrine was required. Her chest X-ray showed bilateral lung injury. Thus, bronchoscopy with bronchoalveolar lavage was requested. Thromboelastometry was performed and resulted in a normal coagulable profile. Despite severe thrombocytopenia (1,000/mm³⁾, fibrinogen levels were increased (1,050mg/dL) due to septic shock. Bronchoscopy was performed without any active or further bleeding. Here, we report the use of thromboelastometry in the diagnosis of coagulation disorders, preventing unnecessary prophylactic platelet transfusion.

Fibrinogen supplementation ex vivo increasesclot firmness comparable to platelet transfusion in thrombocytopenia

BACKGROUND

Fibrinogen concentrate can improve clot firmness and offers a better safety profile than platelet concentrates. Reduction or avoidance of blood transfusions represents a strategy to reduce associated risks. We investigated whether supplementation of fibrinogen concentrate ex vivo can compensate for clot strength as compared with platelet transfusion in vivo METHODS: One hundred patients in need of platelet transfusion (PT) were enrolled. Blood samples were collected immediately before PT and at 1 h and 24 h after PT. Fibrinogen concentrate was added to these citrated whole blood samples at concentrations of 50, 100, 200 and 400 mg kg^-1 and the maximum clot firmness (MCF) was analysed using ROTEM thromboelastometry.

RESULTS

Fibrinogen supplementation increased MCF significantly and dose-dependently before and after PT. The effect of fibrinogen concentrate (equivalent to doses of 100 and 200 mg kg^-1) ex vivo was comparable to that of PT in vivo, whereas 400 mg kg^-1 fibrinogen significantly improved MCF compared with PT (P < 0.001).

CONCLUSIONS

Fibrinogen concentrate can match the effect of PT on MCF in thrombocytopenia. This potential alternative haemostatic intervention should be evaluated in clinical trials.

Benefits of Thromboelastography and Thrombin Generation Assay for Bleeding Prediction in Patients With Thrombocytopenia or Hematologic Malignancies

Background

Thromboelastography (TEG) provides comprehensive information on the whole blood clot formation phases, whereas thrombin generation assay (TGA) reveals the endogenous thrombin levels in plasma. We investigated the potential significance of TEG and TGA parameters for prediction of clinical bleeding in hematologic patients on the basis of the patient's platelet levels.

Methods

TEG and TGA were performed in 126 patients with thrombocytopenia or hematologic malignancies. The bleeding tendencies were stratified on the basis of the World Health Organization bleeding grade.

Results

Maximum amplitude (MA) and clot formation in TEG and endogenous thrombin potential (ETP) in TGA showed significant associations with high bleeding grades (P=0.001 and P=0.011, respectively). In patients with platelet counts ≤10×10⁹/L, low MA values were strongly associated with a high bleeding risk. For bleeding prediction, the area under the curve (AUC) of MA (0.857) and ETP (0.809) in patients with severe thrombocytopenia tended to be higher than that of platelets (0.740) in all patients. Patients with platelet counts ≤10×10⁹/L displayed the highest AUC of the combined MA and ETP (0.929).

Conclusions

Both TEG and TGA were considered to be good predictors of clinical bleeding in patients with severe thrombocytopenia. Combination of the ETP and MA values resulted in a more sensitive bleeding risk prediction in those with severe thrombocytopenia.

Emerging Concepts in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease defined by low platelet counts which presents with an increased bleeding risk. Several genetic risk factors (e.g., polymorphisms in immunity-related genes) predispose to ITP. Autoantibodies and cytotoxic CD8⁺ T cells (Tc) mediate the anti-platelet response leading to thrombocytopenia. Both effector arms enhance platelet clearance through phagocytosis by splenic macrophages or dendritic cells and by induction of apoptosis. Meanwhile, platelet production is inhibited by CD8⁺ Tc targeting megakaryocytes in the bone marrow. CD4⁺ T helper cells are important for B cell differentiation into autoantibody secreting plasma cells. Regulatory Tc are essential to secure immune tolerance, and reduced levels have been implicated in the development of ITP. Both Fcγ-receptor-dependent and -independent pathways are involved in the etiology of ITP. In this review, we present a simplified model for the pathogenesis of ITP, in which exposure of platelet surface antigens and a loss of tolerance are required for development of chronic anti-platelet responses. We also suggest that infections may comprise an important trigger for the development of auto-immunity against platelets in ITP. Post-translational modification of autoantigens has been firmly implicated in the development of autoimmune disorders like rheumatoid arthritis and type 1 diabetes. Based on these findings, we propose that post-translational modifications of platelet antigens may also contribute to the pathogenesis of ITP.

Development and implementation of a novel immune thrombocytopenia bleeding score for dogs

Background

A method of quantifying clinical bleeding in dogs with immune thrombocytopenia (ITP) is needed because ITP patients have variable bleeding tendencies that inconsistently correlate with platelet count. A scoring system will facilitate patient comparisons and allow stratification based on bleeding severity in clinical trials.

Hypothesis/Objectives

To develop and evaluate a bleeding assessment tool for dogs, and a training course for improving its consistent implementation.

Animals

Client‐owned dogs (n = 61) with platelet counts <50,000/μL; 34 classified as primary ITP, 17 as secondary ITP, and 10 as non‐ITP.

Methods

A novel bleeding assessment tool, DOGiBAT, comprising bleeding grades from 0 (none) to 2 (severe) at 9 anatomic sites, was developed. Clinicians and technicians completed a training course and quiz before scoring thrombocytopenic patients. The training course was assessed by randomizing student volunteers to take the quiz with or without prior training. A logistic regression model assessed the association between training and quiz performance. The correlation of DOGiBAT score with platelet count and outcome measures was assessed in the thrombocytopenic dogs.

Results

Clinicians and technicians consistently applied the DOGiBAT, correctly scoring all quiz cases. The odds of trained students answering correctly were higher than those of untrained students (P < .0001). In clinical cases, DOGiBAT score and platelet count were inversely correlated (r_s = −0.527, P < .0001), and DOGiBAT directly correlated with transfusion requirements (r_s = 0.512, P < .0001) and hospitalization duration (r_s = 0.35, P = .006).

Conclusions and Clinical Importance

The DOGiBAT and assessment quiz are simple tools to standardize evaluation of bleeding severity. With further validation, the DOGiBAT may provide a clinically relevant metric to characterize ITP severity and monitor response in treatment trials.

A characteristic flow cytometric pattern with broad forward scatter and narrowed side scatter helps diagnose immune thrombocytopenia (ITP)

Various disorders cause severe thrombocytopenia, which can lead to critical hemorrhage. Procedures that rapidly support the diagnosis and risk factors for serious bleeding were explored, with a focus on immune thrombocytopenia (ITP). Twenty-five patients with thrombocytopenia, including 13 with newly diagnosed ITP, 3 with chronic ITP, 6 with aplastic anemia (AA), and 3 with other thrombocytopenia (one acute myeloid leukemia, one acute lymphoblastic leukemia, and one hemophagocytic lymphohistiocytosis), were reviewed. In addition to platelet-related parameters obtained by an automated hematology analyzer, flow cytometric analysis of platelets was performed. A characteristic flow cytometric pattern with broad forward scatter and narrowed side scatter, which is specific to ITP, but not other types of thrombocytopenia, was found. CD62P-positive platelets were increased in newly diagnosed ITP cases compared to control (P < 0.0001), AA (P = 0.0032). Moreover, detection of dramatic changes in these parameters on sequential monitoring may suggest internal hemorrhage, even absent skin or visible mucosal bleeding. The bleeding score for visible mucosae had a negative correlation with platelet count and a positive correlation with immature platelet fraction (%), forward scatter, and CD62P. This characteristic flow cytometric pattern makes it possible to distinguish ITP from other thrombocytopenic disorders.

Utility of the immature platelet fraction in pediatric immune thrombocytopenia: Differentiating from bone marrow failure and predicting bleeding risk

BACKGROUND

Differentiating childhood immune thrombocytopenia (ITP) from other cause of thrombocytopenia remains a diagnosis of exclusion. Additionally factors that predict bleeding risk for those patients with ITP are currently not well understood. Previous small studies have suggested that immature platelet fraction (IPF) may differentiate ITP from other causes of thrombocytopenia and in combination with other factors may predict bleeding risk.

METHODS

We performed a retrospective chart review of thrombocytopenic patients with an IPF measured between November 1, 2013 and July 1, 2015. Patients were between 2 months and 21 years of age with a platelet count <50 × 10⁹ /l. Each patient chart was reviewed for final diagnosis and bleeding symptoms. A bleeding severity score was retrospectively assigned.

RESULTS

Two hundred seventy two patients met inclusion criteria, 97 with ITP, 11 with bone marrow failure (BMF), 126 with malignancy, and 38 with other causes of thrombocytopenia. An IPF > 5.2% differentiated ITP from BMF with 93% sensitivity and 91% specificity. Absolute immature platelet number (AIPN) was significantly lower in ITP patients with severe to life-threatening hemorrhage than those without, despite similar platelet counts. On multivariate analysis, an IPF < 10.4% was confirmed as an independent predictor of bleeding risk at platelet counts <10 × 10⁹ /l in patients with ITP.

CONCLUSIONS

IPF measurement alone has utility in both the diagnosis of ITP and identifying patients at increased risk of hemorrhage. Further study is required to understand the pathophysiological differences of ITP patients with lower IPF/AIPN.

Targeted Coagulation Management in Severe Trauma: The Controversies and the Evidence

Hemorrhage in the setting of severe trauma is a leading cause of death worldwide. The pathophysiology of hemorrhage and coagulopathy in severe trauma is complex and remains poorly understood. Most clinicians currently treating trauma patients acknowledge the presence of a coagulopathy unique to trauma patients-trauma-induced coagulopathy (TIC)-independently associated with increased mortality. The complexity and incomplete understanding of TIC has resulted in significant controversy regarding optimum management. Although the majority of trauma centers utilize fixed-ratio massive transfusion protocols in severe traumatic hemorrhage, a widely accepted "ideal" transfusion ratio of blood to blood products remains elusive. The recent use of viscoelastic hemostatic assays (VHAs) to guide blood product replacement has further provoked debate as to the optimum transfusion strategy. The use of VHA to quantify the functional contributions of individual components of the coagulation system may permit targeted treatment of TIC but remains controversial and is unlikely to demonstrate a mortality benefit in light of the heterogeneity of the trauma population. Thus, VHA-guided algorithms as an alternative to fixed product ratios in trauma are not universally accepted, and a hybrid strategy starting with fixed-ratio transfusion and incorporating VHA data as they become available is favored by some institutions. We review the current evidence for the management of coagulopathy in trauma, the rationale behind the use of targeted and fixed-ratio approaches and explore future directions.

Predictive Value of Mean Platelet Volume in Variceal Bleeding due to Cirrhotic Portal Hypertension

Aim:

To investigate whether mean platelet volume (MPV) is a predictor of variceal bleeding in patients with cirrhotic portal hypertension.

Materials and methods:

This prospective cohort was performed in the internal medicine department of our tertiary care center. Cirrhotic patients were allocated into two groups: Group I consisted of 31 cases without a history of variceal bleeding, whereas group II was made up of 31 patients with a history of variceal bleeding. Data derived from medical history, physical examination, ultrasonography, gastrointestinal system endoscopy, complete blood count, hepatic, and renal function tests were recorded and compared between two groups. On physical examination, encephalopathy and ascites were evaluated and graded with respect to Child-Pugh-Turcotte classification.

Results:

There was no significant difference between the two groups in terms of age, duration of the disease, and gender of the patient. The only remarkable difference was that hemoglobin (p = 0.02) and hematocrit (p = 0.02) values were lower in group II. Neither the etiology of bleeding was different between groups nor did MPV seem to have a noteworthy impact on bleeding. Interestingly, risk of variceal bleeding increased in parallel to the higher grade of varices.

Conclusion:

Our results imply that there is a correlation between the grade of varices and esophageal vari-ceal bleeding in cirrhotic patients. However, association between MPV and variceal bleeding could not be demonstrated. Utilization of noninvasive tests as predictors in these patients necessitates further controlled trials on larger series.

How to cite this article: Erdogan MA, Benli AR, Acmali SB, Koroglu M, Atayan Y, Danalioglu A, Kayhan B. Predictive Value of Mean Platelet Volume in Variceal Bleeding due to Cirrhotic Portal Hypertension. Euroasian J Hepato-Gastroenterol 2017;7(1):6-10.

Evaluation of platelet function in thrombocytopenia

Whole blood aggregometry is a functional assay for determination of platelet function. Until now, whole blood aggregometry has not been considered feasible at low platelet counts. Hence, the objectives of the present study were to explore platelet function in thrombocytopenia using a novel index of impedance aggregometry adjusted for platelet count and evaluate the association to platelet function assessed by flow cytometry. Hirudin anticoagulated blood was collected from 20 healthy volunteers, 20 patients with primary immune thrombocytopenia (ITP), and 17 hematological cancer patients. Platelet function was analyzed by impedance aggregometry and by flow cytometry. Collagen, adenosine diphosphate, thrombin receptor agonist peptide-6, and ristocetin were used as agonists for both analyses. Thrombocytopenia in healthy whole blood was induced in vitro employing a recently published method. Platelet aggregation of thrombocytopenic patients was evaluated relative to the aggregation of healthy volunteers at the same platelet count. In flow cytometry, platelet function was described as expression of the platelet surface glycoproteins: bound fibrinogen, CD63, and P-selectin. Similar platelet counts were obtained in the patient groups (p = 0.69) (range: 13-129 × 10⁹/l). Aggregation adjusted for platelet count was significantly increased in ITP patients compared to healthy platelets across all agonists. The platelet aggregation was high in the 95% prediction interval, with 18 ITP patients above the prediction interval in at least two agonists. In contrast, the platelet aggregation was low in the prediction interval in cancer patients, and three cancer patients with platelet aggregation below the prediction interval in at least one agonist. ITP patients displayed increased expression of bound fibrinogen and CD63 following activation, compared with particularly cancer patients, but also compared with healthy platelets. This study demonstrated the feasibility of a novel approach to perform platelet function analyses in thrombocytopenia using impedance aggregometry adjusted for platelet count.