How to approach thrombocytopenia

Incidence, Risk Factors, and Outcomes of Thrombocytopenia in Older Medical Inpatients: A Prospective Cohort Study

BACKGROUND

Thrombocytopenia, defined as a platelet count of less than 150 × 109/L, is a frequent condition among hospitalized patients and presents unique challenges in diagnosis and management. Despite its commonality, data on incidence and related risk factors in medical inpatients remain limited, especially in older people.

METHODS

A 2-year prospective cohort study with a 3-year follow-up was conducted on inpatients aged ≥65 years admitted to a medical ward. Clinical data were collected, including demographics, comorbidities, laboratory results, and outcomes. Multivariate logistic regression analysis assessed risk factors associated with non-resolution of thrombocytopenia and mortality.

RESULTS

The study included 961 older inpatients with a mean age of 82 years. Thrombocytopenia occurred in 22.6% of the study population. The most common causes were infections (57.4%) and drug-induced thrombocytopenia (25.3%). The non-resolution of thrombocytopenia was noted in 59% of patients. In-hospital and 3-year mortality was significantly higher in this subgroup compared to the rest (24.5% vs. 12.7%, p = 0.015) and (72.4% vs. 59.8%, p = 0.04, respectively). In multivariate analysis, nadir platelet count and hematologic disease were independent factors associated with the non-resolution of thrombocytopenia. Furthermore, in individuals with thrombocytopenia, the administration of norepinephrine (p < 0.001) and a higher clinical frailty score (p < 0.001) were observed as independent mortality predictors.

CONCLUSIONS

Thrombocytopenia in older medical inpatients is associated with poor prognosis, particularly in those with non-resolution thrombocytopenia. Early identification and targeted management may improve outcomes.

Increased risk of haematological malignancy in adults over age 60 with thrombocytopenia compared with matched controls: Time for an upfront bone marrow evaluation?

International societies have conflicting recommendations on whether bone marrow aspirate/biopsy (BMB) is needed during workup for isolated thrombocytopenia. Our objective was to determine if thrombocytopenia in patients aged ≥60 years is associated with an increased incidence of haematological malignancy. We performed a retrospective population-based cohort study in patients aged ≥60 years between January 1, 2009 to December 31, 2019. Exposed patients had specialist consultation for thrombocytopenia, with platelet count <100 × 109/L, but normal haemoglobin and white blood cell count. Unexposed patients were those who never had specialist consultation for thrombocytopenia and whose platelets were ≥100 × 109/L. The primary outcome was the diagnosis of haematological malignancy using a competing risk of death model. During 4.0 years (IQR 2.2-6.7) of follow-up, 378/4930 exposed (19.1/1000PY, 95% CI 17.1-21.0), and 204/17556 unexposed patients (2.5/1000PY, 95% CI 2.2-2.8) were diagnosed with haematological malignancy (HR 15.5 (95% CI 11.3-21.4, p < 0.0001) in year 1, and 5.3 (95% CI 4.4-6.6, p < 0.0001) in years 2+). This finding persisted in analyses stratified by sex, age, severity, or duration of thrombocytopenia, and treatment with corticosteroids within 2 weeks of consultation. This study found a strong association between isolated thrombocytopenia and haematological malignancy in patients ≥60 years, supporting consideration of diagnostic testing including BMB during outpatient specialist consultation.

Plasma lipids paediatric reference intervals: Indirect estimation using a large 14-year database

OBJECTIVES

Establishing direct reference intervals (RIs) for paediatric patients is a very challenging endeavour. Indirect RIs can address this problem, using existing clinical laboratory databases from real-world data research. Compared to the traditional direct method, the indirect approach is highly practical, widely applicable, and low-cost. Considering the relevance of dyslipidemia in the paediatric age, to provide better laboratory services to the local paediatric population, we established population-specific lipid RIs via data mining.

METHODS

Our laboratory information system was searched for cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) of patients aged less than 18 years, performed from January 2009 until December 2022. RIs were estimated using RefineR algorithm.

RESULTS

Values from 215,594 patients were initially collected. After refining data on the basis of specific exclusion criteria that left 17,933 patients, we determined the RIs for each analyte, including corresponding 95% confidence interval (95% CI). Age and sex partitions were required for proper stratification of the heterogenous subpopulations. Age-related variations in TC and TG values were observed mainly in children until 5 years. RIs were defined for children less than 3 years and for those of 3-18 years. In our population, the obtained RIs were comparable with those of the literature, but the upper TG limit in subjects under the age of 3 (2.03 mmol/L with 95% CI: 1.45-2.86) was lower than that previously reported.

CONCLUSIONS

Our RIs, necessary for paediatric lipid monitoring, are tailored to the serviced patient population as should be done whenever possible.

An Introduction to the Complete Blood Count for Clinical Chemists: Platelets

BACKGROUND

The most ordered laboratory test worldwide is the complete blood count (CBC).

CONTENT

In this primer, an introduction to platelet testing in the context of the CBC is provided with a discussion of the laboratory evaluation of platelet abnormalities including thrombocytopenia and thrombocytosis.

SUMMARY

As clinical chemists continue to be tasked to direct laboratories outside of the traditional clinical chemistry sections such as hematology, expertise must be developed. This primer is dedicated to that effort.

An acoustofluidic device for the automated separation of platelet-reduced plasma from whole blood

Separating plasma from whole blood is an important sample processing technique required for fundamental biomedical research, medical diagnostics, and therapeutic applications. Traditional protocols for plasma isolation require multiple centrifugation steps or multiunit microfluidic processing to sequentially remove large red blood cells (RBCs) and white blood cells (WBCs), followed by the removal of small platelets. Here, we present an acoustofluidic platform capable of efficiently removing RBCs, WBCs, and platelets from whole blood in a single step. By leveraging differences in the acoustic impedances of fluids, our device generates significantly greater forces on suspended particles than conventional microfluidic approaches, enabling the removal of both large blood cells and smaller platelets in a single unit. As a result, undiluted human whole blood can be processed by our device to remove both blood cells and platelets (>90%) at low voltages (25 Vpp). The ability to successfully remove blood cells and platelets from plasma without altering the properties of the proteins and antibodies present creates numerous potential applications for our platform in biomedical research, as well as plasma-based diagnostics and therapeutics. Furthermore, the microfluidic nature of our device offers advantages such as portability, cost efficiency, and the ability to process small-volume samples.

Hemostasis Testing in the Emergency Department: A Narrative Review

Routine laboratory screening is typically performed at initial evaluation of the vast majority of presentations to the emergency department (ED). These laboratory results are crucial to the diagnostic process, as they may influence up to 70% of clinical decisions. However, despite the usefulness of biological assessments, many tests performed are inappropriate or of doubtful clinical relevance. This overutilization rate of laboratory testing in hospitals, which represents a significant medical-economic burden, ranges from 20 to 67%, with coagulation tests at the top of the list. While reviews frequently focus on nonintensive care units, there are few published assessments of emergency-specific interventions or guidelines/guidance to date. The aim of this review is to highlight current recommendations for hemostasis evaluation in the emergency setting with a specific analysis of common situations leading to ED admissions, such as suspected venous thrombosis or severe bleeding. We revisit the evidence related to the assessment of patient's hemostatic capacity based on comprehensive history taking and physical examination as well as best practice recommendations for blood sample collection to ensure the reliability of results. This review also includes an examination of various currently available point of care tests and a comprehensive discussion on indications, limitations, and interpretation of these tests.

Risk and adverse clinical outcomes of thrombocytopenia among patients with solid tumors-a Danish population-based cohort study

BACKGROUND

Knowledge about thrombocytopenia among patients with solid tumors is scarce. We examined the risk of thrombocytopenia among patients with solid tumors and its association with adverse outcomes.

METHODS

Using Danish health registries, we identified all patients with incident solid tumors from 2015-2018 (n = 52,380) and a platelet count measurement within 2 weeks prior to or on their cancer diagnosis date. The risk of thrombocytopenia was categorized as grades 0 (any platelet count × 109/L): <150; 1: <100; 2: <75; 3: <50; 4: <25, and 5: <10. To study the outcomes, each patient with thrombocytopenia was matched with up to five cancer patients without thrombocytopenia by age, sex, cancer type, and stage. Cox regression was used to compute hazard ratios (HRs) of bleeding, transfusion, or death, adjusting for confounding factors.

RESULTS

The 1-year risk of thrombocytopenia was 23%, increasing to 30% at 4 years. This risk was higher in patients receiving chemotherapy (43% at 1 year and 49% at 4 years). Overall, patients with thrombocytopenia had higher 30-days rates of bleeding (HR = 1.72 [95% confidence interval, CI: 1.41-2.11]). Thrombocytopenia was also associated with an increased rate of transfusion, and death, but some of the risk estimates were imprecise.

CONCLUSIONS

The risk of thrombocytopenia was substantial among patients with solid tumors and associated with adverse outcomes.

The Challenge for a Correct Diagnosis of Refractory Thrombocytopenia: ITP or MDS with Isolated Thrombocytopenia?

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by isolated thrombocytopenia. It is diagnosed in patients with a platelet count below 100,000 per cubic millimeter in whom other causes of thrombocytopenia have been ruled out, and its diagnosis is generally one of exclusion. Clinical manifestations of patients may vary from asymptomatic disease to mild mucocutaneous or life-threatening bleeding. Glucocorticoids are used as first-line treatment for ITP, while other second-line medications, mainly thrombopoietin-receptor agonists (TPO-RA) and rituximab, are given to patients in whom ITP does not remit, or relapses soon after glucocorticoid treatment. Refractoriness of ITP strongly questions its diagnosis and necessitates a thorough clinical and laboratory work-up to decide whether that is the case of refractory ITP or a misdiagnosis. The aim of this review is to summarize the conditions associated with isolated thrombocytopenia and highlight the characteristics of confusing cases. Even though the case of a myelodysplastic syndrome presented with isolated thrombocytopenia (MDS-IT) is relatively rare and not well-established in the literature, it constitutes one of the most predominant misdiagnoses of refractory ITP. MDS-IT patients are thought to present with multilineage dysplasia, normal karyotype and low risk prognostic score, based on IPSS-R. It has been shown that a significant proportion of MDS-IT patients are misdiagnosed as having the more common ITP. Therefore, it is crucial that in confusing cases of persistent thrombocytopenia a detailed diagnostic work-up is applied-including evaluation of peripheral-blood smear, bone marrow examination and cytogenetic testing-to avoid unnecessary therapy delay.

Egyptian Pediatric Guidelines for the Management of Children with Isolated Thrombocytopenia Using the Adapted ADAPTE Methodology-A Limited-Resource Country Perspective

BACKGROUND

Thrombocytopenia is a prevalent presentation in childhood with a broad spectrum of etiologies, associated findings, and clinical outcomes. Establishing the cause of thrombocytopenia and its proper management have obvious clinical repercussions but may be challenging. This article provides an adaptation of the high-quality Clinical Practice Guidelines (CPGs) of pediatric thrombocytopenia management to suit Egypt's health care context.

METHODS

The Adapted ADAPTE methodology was used to identify the high-quality CPGs published between 2010 and 2020. An expert panel screened, assessed and reviewed the CPGs and formulated the adapted consensus recommendations based on the best available evidence.

DISCUSSION

The final CPG document provides consensus recommendations and implementation tools on the management of isolated thrombocytopenia in children and adolescents in Egypt. There is a scarcity of evidence to support recommendations for various management protocols. In general, complete clinical assessment, full blood count, and expert analysis of the peripheral blood smear are indicated at initial diagnosis to confirm a bleeding disorder, exclude secondary causes of thrombocytopenia and choose the type of work up required. The International Society of Hemostasis and thrombosis-Bleeding assessment tool (ISTH-SCC BAT) could be used for initial screening of bleeding manifestations. The diagnosis of immune thrombocytopenic purpura (ITP) is based principally on the exclusion of other causes of isolated thrombocytopenia. Future research should report the outcome of this adapted guideline and include cost-analysis evaluations.

Thrombocytopenia Following Perceval Sutureless Aortic Valve Replacement in Asian Patients

BACKGROUND

This study analyzed the safety and performance of the Perceval valve for aortic valve replacement (AVR) in patients at 1 year after undergoing aortic stenosis (AS) treatment, and its effect on significant declines in the platelet count during the immediate postoperative period.

METHODS AND RESULTS

Data were collected retrospectively for the initial 121 patients (median age 77 years; 47.1% females) who underwent Perceval sutureless AVR between May 2019 and July 2022. Implantation was successful in all (100%), with median cross-clamp and CPB times of 59 and 100 min, respectively. Postoperative thrombocytopenia (platelet count <50×103/μL) was noted in 80 (66.1%) patients. Multivariate analysis showed advanced age (>80 years), preoperative low platelet count (<200×103/μL), and a sternotomy approach as significant risk factors for postoperative thrombocytopenia. One (0.8%) patient died within 30 days after the procedure. The 2-year site-reported event rate was 14% (n=17) for all-cause mortality, 0.8% (n=1) for cardiac mortality, 4.1% (n=5) for stroke, and 1.7% (n=2) for endocarditis and valve-related reoperation; there were no instances of paravalvular leakage or structural valve deterioration.

CONCLUSIONS

Thrombocytopenia was common after Perceval sutureless AVR, although its impact was not significant. Although Perceval sutureless AVR was found to be a safe and effective option, preoperative assessment of potential bleeding should be performed and the Perceval valve should not be used for patients with a high bleeding risk.

How I diagnose and treat thrombocytopenia in geriatric patients

ABSTRACT

Thrombocytopenia in older individuals is a common but diagnostically challenging condition that has variable clinical impact to those who are affected. Diagnostic approach requires evaluation of the preexisting clinical conditions, detailed review of medications, and assessment for disorders that warrant urgent treatment. In this article, we describe a systematic approach to diagnosis of thrombocytopenia and present a schematic review for management strategies. Three clinical scenarios are presented that are relevant for their prevalence and management challenges in an older adult population. The first scenario addresses primary immune thrombocytopenia (ITP) and reviews different treatment options. The second one addresses complications of thrombocytopenia in management of the myelodysplastic syndrome. The last one reviews diagnostic challenges of drug-induced ITP.

A Comparative Analysis of Effectiveness of Recombinant Interleukin-11 Versus Papaya Leaf Extract for Treatment of Thrombocytopenia: A Review

Platelets or thrombocytes play an important role in thrombosis and maintaining hemostasis. Thrombocytes help in forming blood clots at the site of the wound. When the level of platelets decreases, uncontrolled bleeding occurs which can result in mortality. A decrease in the blood platelet level is known as thrombocytopenia which can be caused due to various reasons. A variety of treatment options are available for thrombocytopenia like platelet transfusion, splenectomy, platelet management with various types of corticosteroids, and recombinant interleukin-11 (rhIL-11). The use of rhIL-11 is approved by FDA for the treatment of thrombocytopenia. rhIL-11 is a recombinant cytokine that is administered to patients suffering from chemotherapy-induced thrombocytopenia as it enhances megakaryocytic proliferation which aids in platelet production. But this treatment has various side effects and is costly. Hence, there is a crucial need to identify cost-effective alternative strategies that present no side effects. The majority of the population in low-income countries requires a functional and cost-effective treatment for low thrombocyte count. Carica papaya is a tropical herbaceous plant that has been reported in recovering low platelet count during dengue virus infection. Even though multiple benefits of the Carica papaya leaf extract (CPLE) are popular, the active compound present in it, which mediates these benefits, remains to be identified. This review aims to highlight the different aspects of rhIL-11 and CPLE-induced platelet counts and their limitations and benefits in the treatment of thrombocytopenia. The literature related to the treatment of thrombocytopenia using rhIL-11 and CPLE from 1970 to 2022 was searched using PubMed and Google Scholar databases with the keywords Recombinant Interleukin-11, Papaya Leaf Extract, Thrombocytopenia, and Platelets.

Routine clinical parameters and laboratory testing predict therapy-related myeloid neoplasms after treatment for breast cancer

We aim to identify predictors of therapy-related myeloid neoplasms (t-MN) in patients with breast cancer (BC) and cytopenias to determine the timing of bone marrow biopsy (BMBx). Patients with BC and cytopenias who were referred for BMBx between 2002-2018 were identified using the Memorial Sloan Kettering Cancer Center institutional database. Characteristics associated with the risk of t-MN were evaluated by multivariable logistic regression and included in a predictive model. The average area under the receiver operating characteristic curve (AUC) was estimated by 5-fold cross-validation. Of the 206 BC patients who underwent BMBx included in our study, 107 had t-MN. By multivariable analysis, white blood cell count 4-11 K/mcL, absolute neutrophil count (ANC) ≥1.5 K/mcL, hemoglobin ≥12.2 g/dL, red cell distribution width 11.5-14.5%, the presence of bone metastasis and a time from BC diagnosis to BMBx <15 months significantly decreased the likelihood of t-MN. The average AUC was 0.88. We stratified our cohort by bone metastasis and by findings on peripheral smear. In both the subset without bone metastasis (n=159) and in the cohort with no blasts or dysplastic cells on peripheral smear (n=96) our variables had similar effects on the risk of t-MN. Among the 47 patients with bone metastasis, an ANC ≥1.5 K/mcL was the only variable associated with a decreased risk of t-MN. Our findings show that in patients with BC and unexplained cytopenias, clinical and laboratory parameters can predict t-MN and assist clinicians in determining the timing of a BMBx.

Renal Klotho safeguards platelet lifespan in advanced chronic kidney disease through restraining Bcl-xL ubiquitination and degradation

BACKGROUND

Thrombosis and hemorrhage as two opposite pathologies are prevalent within the chronic kidney disease (CKD) population. Platelet homeostasis, which positions centrally in their pathogenesis, varies among the CKD population, while the underlying mechanism is poorly understood.

OBJECTIVE

To investigate the change character and mechanism of platelet homeostasis in CKD and its association with renal Klotho deficiency.

METHODS

The change character of platelet homeostasis and its association with renal Klotho deficiency were determined based on a cohort study as well as CKD mice and Klotho-deficient mice with CKD. The effects on thrombopoiesis and platelet lifespan were examined by flow cytometry and platelet transfer. The underlying mechanism was explored by proteomics, flow cytometry, western blot, and immunoprecipitation.

RESULTS

We show that platelet count declines both in patient and mouse models with advanced CKD (Adv-CKD) and is positively associated with circulating Klotho levels. Mechanistically, we identify that ubiquitin ligase UBE2O governs Bcl-xL ubiquitination and degradation in platelets, whereas Adv-CKD-induced oxidative stress in platelets stimulates p38MAPK to promote Bcl-xL phosphorylation, which facilitates UBE2O binding to Bcl-xL and subsequent Bcl-xL degradation. Consequently, platelet lifespan is shortened in Adv-CKD, culminating in platelet count decline. However, kidney-secreted soluble Klotho protein restricts oxidative stress in platelets, thereby preserving Bcl-xL expression and platelet lifespan.

CONCLUSIONS

Our findings uncover the mechanism of platelet count decline in Adv-CKD and identify renal Klotho as a long-range regulator of platelet lifespan, which not only provide a molecular mechanism underlying CKD-associated thrombocytopenia and hemorrhage but also offer a promising therapy choice.

Resolved Hypereosinophilic Syndrome and Immune Thrombocytopenic Purpura in Ulcerative Colitis Patients Post Colectomy: A Case Series and Literature Review

Introduction

Hypereosinophilic syndrome (HES) and immune thrombocytopenic purpura (ITP) have been reported to co-occur with ulcerative colitis (UC). However, the exact pathogenic mechanisms of their occurrence remain elusive. In this article, we aim to describe two cases of UC patients who developed refractory HES and ITP and elaborate on their potential pathogenesis.

Case Study

We report two middle-aged patients diagnosed with UC. The first patient developed HES that was refractory to conventional medical therapy of idiopathic HES, and the second developed refractory ITP that failed steroid and immunosuppressive therapy. Both conditions improved considerably following colectomy, suggesting they are of a reactive rather than idiopathic nature.

Conclusion

In patients with UC and refractory comorbid HES or ITP, the reactive nature of these comorbidities should be taken into consideration, and colectomy, therefore, should be considered if clinically indicated.

Pantoprazole-Associated Thrombocytopenia: A Literature Review and Case Report

Proton-pump inhibitors (PPIs) are commonly utilized in the treatment of upper gastrointestinal bleeds (UGIBs) due to their ability to stabilize blood clot formation. PPIs have been shown to reduce rebleeding after endoscopic hemostasis and reduce signs of bleeding at index endoscopy. While PPIs are well-tolerated and commonly administered to patients suffering from acute UGIBs, significant adverse effects may occur. Patients have reported various mild systemic symptoms during short-term PPI use, including headache, rash, dizziness, nausea, abdominal pain, flatulence, constipation, and diarrhea. In general, serious side effects of PPIs tend to be mild during treatment periods under two weeks; however, as the treatment duration increases, side effects have been observed to increase in frequency and severity. PPI-induced thrombocytopenia is an exceedingly rarely reported adverse reaction that remains largely unstudied due to the dearth of patient cases. This adverse effect continues to be a diagnosis of exclusion, and there are no current evidence-based recommendations to approach this complication. Thrombocytopenia increases the risk of rebleeding and hemodynamic instability, which may be devastating to patients suffering from UGIBs. Here, we present a case of thrombocytopenia that began after the introduction of pantoprazole in the setting of a UGIB. The thrombocytopenia resolved promptly after cessation of the medication. We highlight this case to increase awareness of this rare finding given the lack of recommendations for short-term PPI-induced thrombocytopenia.

Primary care coverage and individual health: evidence from a likelihood model using biomarkers in Brazil

Background

Although the use of biomarkers to assess health outcomes has recently gained momentum, literature is still scarce for low- to middle-income countries. This paper explores the relationship between primary care coverage and individual health in Brazil using a dataset of blood-based biomarkers collected by the Brazilian National Health Survey. Both survey data and laboratory results were crossed with coverage data from the Family Health Strategy (ESF) program, the most important primary care program in Brazil; the coverage measures aim to capture both direct (household) and indirect (spill-over) effects.

Methods

The empirical strategy used a probit model to estimate the relationship between ESF program coverage and the likelihood of abnormal biomarker levels while controlling for a rich set of individual and household characteristics based on data from the national survey.

Results

Household ESF coverage was associated with a lower likelihood of abnormal results for biomarkers related to anemia (marginal effect between − 2.16 and − 2.18 percentage points), kidney failure (between − 1.01 and − 1.19 p.p.), and arterial hypertension (between − 1.48 and − 1.64 p.p). The likelihood of abnormal levels of white blood cells and thrombocytes was negatively related to primary care coverage (marginal effect between − 1.8 and − 2 p.p.). The spillover effects were relevant for kidney failure and arterial hypertension, depending on the regional level. Although not sensitive to household coverage, diabetes mellitus was negatively associated with the state supply of primary care, and abnormal cholesterol levels did not present any relationship with ESF program coverage.

Conclusions

The presence of spillover effects of ESF program coverage regarding these conditions reveals that the strengthening of primary care by increasing the household registration and the regional density of ESF teams is an efficient strategy to address important comorbidities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-07329-9.

Thrombocytopenia and clear corneal incision cataract surgery

PURPOSE

To investigate complications and outcomes of clear corneal incision cataract surgery in patients with thrombocytopenia.

SETTING

1 veterans hospital and 2 academic medical centers.

DESIGN

Multicenter retrospective chart review.

METHODS

All eyes of thrombocytopenic patients that underwent clear corneal incision cataract surgery with a platelet count of 100 × 103/μL or less measured within 30 days prior to surgery were included. Subject demographics, intraoperative complications, use of pupillary expansion devices, use of local anesthetic injections, and change in corrected distance visual acuity were recorded.

RESULTS

3 sites recorded 40 113 clear corneal incision cataract surgeries, of which 196 eyes (0.49%) of 150 thrombocytopenic patients were recorded. The mean platelet count in the study subjects was 73.0 ± 20.5 × 103/μL. Two cases of intraoperative iris hemorrhage that were readily and controlled occurred in conjunction with pupillary expansion. There were no bleeding complications associated with retrobulbar, peribulbar, or sub-Tenon anesthetic injections. There was a statistically significant improvement (P < .0001) in visual acuity post-operatively.

CONCLUSIONS

Clear corneal incision cataract surgery with pupillary expansion devices and local anesthetic injections can be safely performed in patients with thrombocytopenia.

Coagulopathy and sepsis: Pathophysiology, clinical manifestations and treatment

Sepsis is a complex syndrome with a high incidence, increasing by 8.7% annually over the last 20 years. Coagulopathy is a leading factor associated with mortality in patients with sepsis and range from slight thrombocytopenia to fatal disorders, such as disseminated intravascular coagulation (DIC). Platelet reactivity increases during sepsis but prospective trials of antiplatelet therapy during sepsis have been disappointing. Thrombocytopenia is a known predictor of worse prognosis during sepsis. The mechanisms underlying thrombocytopenia in sepsis have yet to be fully understood but likely involves decreased platelet production, platelet sequestration and increased consumption. DIC is an acquired thrombohemorrhagic syndrome, resulting in intravascular fibrin formation, microangiopathic thrombosis, and subsequent depletion of coagulation factors and platelets. DIC can be resolved with treatment of the underlying disorder, which is considered the cornerstone in the management of this syndrome. This review presents the current knowledge on the pathophysiology, diagnosis, and treatment of sepsis-associated coagulopathies.

Autologous Induced Pluripotent Stem Cell-Based Cell Therapies: Promise, Progress, and Challenges

The promise of human induced pluripotent stem cells (iPSCs) lies in their ability to serve as a starting material for autologous, or patient-specific, stem cell-based therapies. Since the first publications describing the generation of iPSCs from human tissue in 2007, a Phase I/IIa clinical trial testing an autologous iPSC-derived cell therapy has been initiated in the U.S., and several other autologous iPSC-based therapies have advanced through various stages of development. Three single-patient in-human transplants of autologous iPSC-derived cells have taken place worldwide. None of the patients suffered serious adverse events, despite not undergoing immunosuppression. These promising outcomes support the proposed advantage of an autologous approach: a cell therapy product that can engraft without the risk of immune rejection, eliminating the need for immunosuppression and the associated side effects. Despite this advantage, there are currently more allogeneic than autologous iPSC-based cell therapy products in development due to the cost and complexity of scaling out manufacturing for each patient. In this review, we highlight recent progress toward clinical translation of autologous iPSC-based cell therapies. We also highlight technological advancements that would reduce the cost and complexity of autologous iPSC-based cell therapy production, enabling autologous iPSC-based therapies to become a more commonplace treatment modality for patients. © 2021 The Authors.

Perioperative thrombocytopenia

PURPOSE OF REVIEW

In this review, we discuss recent developments and trends in the perioperative management of thrombocytopenia.

RECENT FINDINGS

Large contemporary data base studies show that preoperative thrombocytopenia is present in about 8% of asymptomatic patients, and is associated with increased risks for bleeding and 30-day mortality. Traditionally specific threshold platelet counts were recommended for specific procedures. However, the risk of bleeding may not correlate well with platelet counts and varies with platelet function depending on the underlying etiology. Evidence to support prophylactic platelet transfusion is limited and refractoriness to platelet transfusion is common. A number of options exist to optimize platelet counts prior to procedures, which include steroids, intravenous immunoglobulin, thrombopoietin receptor agonists, and monoclonal antibodies. In addition, intraoperative alternatives and adjuncts to transfusion should be considered. It appears reasonable to use prophylactic desmopressin and antifibrinolytic agents, whereas activated recombinant factor VII could be considered in severe bleeding. Other options include enhancing thrombin generation with prothrombin complex concentrate or increasing fibrinogen levels with fibrinogen concentrate or cryoprecipitate.

SUMMARY

Given the lack of good quality evidence, much research remains to be done. However, with a multidisciplinary multimodal perioperative strategy, the risk of bleeding can be decreased effectively.

Clinical challenges and promising therapies for chemotherapy-induced thrombocytopenia

Introduction: Chemotherapy-induced thrombocytop enia (CIT) is a common complication of cancer treatment causing chemotherapy delays, dose reductions, and treatment discontinuation, negatively impacting treatment outcomes and putting patients at risk for bleeding complications. There is no FDA-approved agent available to manage CIT.Areas covered: This article covers the diagnosis, definitions, and clinical challenges of CIT, and then focuses on the therapeutics developed to manage CIT. The first-generation thrombopoietic agents (oprelvekin and recombinant human thrombopoietins) are reviewed for critical background and context, followed by a detailed discussion of the data for the thrombopoietin receptor agonists (TPO-RAs) to manage CIT. Efficacy of TPO-RAs in treatment and prevention of CIT, as well as safety concerns such as the risk of thromboembolic complications, are reviewed in detail. For this review, a PubMed/MEDLINE literature search was undertaken for relevant articles published from 1995-2021.Expert opinion: After over two decades of drug development for CIT, multiple clinical trials and observational studies have found TPO-RAs, in particular romiplostim, to be safe and effective agents to manage patients with CIT, although no agent is yet FDA-approved for this indication. Active management of CIT with TPO-RAs is likely to improve oncologic outcomes, although additional data are needed. Phase 3 trials are ongoing.

Anticoagulation in Patients with Platelet Disorders

Platelet disorders comprise heterogeneous diseases featured by reduced platelet counts and/or impaired platelet function causing variable bleeding symptoms. Despite their bleeding diathesis, patients with platelet disorders can develop transient or permanent prothrombotic conditions that necessitate prophylactic or therapeutic anticoagulation. Anticoagulation in patients with platelet disorders is a matter of concern because the bleeding risk could add to the hemorrhagic risk related to the platelet defect. This review provides an overview on the evidence on anticoagulation in patients with acquired and inherited thrombocytopenia and/or platelet dysfunction. We summarize tools to evaluate and balance bleeding- and thrombotic risks and describe a practical approach on how to manage these patients if they have an indication for prophylactic or therapeutic anticoagulation.

Thrombocytopenia in Virus Infections

Thrombocytopenia, which signifies a low platelet count usually below 150 × 10⁹/L, is a common finding following or during many viral infections. In clinical medicine, mild thrombocytopenia, combined with lymphopenia in a patient with signs and symptoms of an infectious disease, raises the suspicion of a viral infection. This phenomenon is classically attributed to platelet consumption due to inflammation-induced coagulation, sequestration from the circulation by phagocytosis and hypersplenism, and impaired platelet production due to defective megakaryopoiesis or cytokine-induced myelosuppression. All these mechanisms, while plausible and supported by substantial evidence, regard platelets as passive bystanders during viral infection. However, platelets are increasingly recognized as active players in the (antiviral) immune response and have been shown to interact with cells of the innate and adaptive immune system as well as directly with viruses. These findings can be of interest both for understanding the pathogenesis of viral infectious diseases and predicting outcome. In this review, we will summarize and discuss the literature currently available on various mechanisms within the relationship between thrombocytopenia and virus infections.

Bardet-Biedl Syndrome ciliopathy is linked to altered hematopoiesis and dysregulated self-tolerance

Bardet-Biedl Syndrome (BBS) is a pleiotropic genetic disease caused by the dysfunction of primary cilia. The immune system of patients with ciliopathies has not been investigated. However, there are multiple indications that the impairment of the processes typically associated with cilia may have influence on the hematopoietic compartment and immunity. In this study, we analyze clinical data of BBS patients and corresponding mouse models carrying mutations in Bbs4 or Bbs18. We find that BBS patients have a higher prevalence of certain autoimmune diseases. Both BBS patients and animal models have altered red blood cell and platelet compartments, as well as elevated white blood cell levels. Some of the hematopoietic system alterations are associated with BBS-induced obesity. Moreover, we observe that the development and homeostasis of B cells in mice is regulated by the transport complex BBSome, whose dysfunction is a common cause of BBS. The BBSome limits canonical WNT signaling and increases CXCL12 levels in bone marrow stromal cells. Taken together, our study reveals a connection between a ciliopathy and dysregulated immune and hematopoietic systems.

Prevalence and aetiology of moderate and severe thrombocytopenia in a tertiary and quaternary centre in KwaZulu-Natal

Background

Thrombocytopenia is a common haematological disorder, characterised by platelet counts below 150 × 10⁹/L. The aetiology of thrombocytopenia is multifactorial; notably, in a misdiagnosis this condition may be due to pre-analytical laboratory artefacts. Knowledge about the common aetiology of thrombocytopenia will assist clinicians in decision-making and interpretation of laboratory tests and this may lead to prompt, adequate patient management and cost-saving measures.

Objective

This study determined the prevalence and aetiology of moderate and severe thrombocytopenia in a tertiary or quaternary laboratory in Durban, KwaZulu-Natal, South Africa.

Methods

We conducted a retrospective study at the Inkosi Albert Luthuli Central Hospital haematology laboratory between October 2015 and April 2016. A total of 2076 full blood count results with a platelet count of less than 100 × 10⁹/L were retrieved from the Inkosi Albert Luthuli Academic Hospital database. Laboratory data were extracted and matched with clinical data and used to identify the potential aetiology of thrombocytopenia.

Results

The prevalence of thrombocytopenia was 14.9% within the selected study period. The haematology or oncology wards and clinic accounted for 55.2% of thrombocytopenia cases, whereas the adult and paediatric intensive care units accounted for 29.3%. Notably, 15.5% of thrombocytopenia cases were reported in non-haematology wards and clinics. The most common cause of thrombocytopenia was chemotherapy which accounted for 38.5% of all causes.

Conclusion

In our tertiary and quaternary setting, thrombocytopenia in adults was most common in patients admitted to haematology and oncology wards. Moreover, chemotherapy-induced thrombocytopenia accounted for more than a third of all these cases.

Complications of Dentoalveolar Surgery

This article explores how to prevent and manage complications of dentoalveolar surgery. Many complications are avoidable. Surgical skills and knowledge of anatomy play an important role in prevention of complications. Prevention starts with detailed history and physical examination of the patient. Key to perioperative management of patients is risk assessment. Without a proper history and physical examination, the clinician is unable to assess the risk of performing surgery and anesthesia for each patient. Some illnesses and medications increase the risk of complications. The following complications are discussed: alveolar osteitis, displacement, fracture, hemorrhage, infection, nonhealing wound, oroantral communication, swelling, and trismus.

Optimized tool for evaluation of platelet function measured by impedance aggregometry

Platelet aggregation measured by impedance aggregometry is highly dependent on platelet count. We previously developed a tool to interpret impedance aggregometry based on the strong linear correlation between platelet counts and platelet aggregation at reduced platelet counts. The present study aimed to optimize the tool by expanding the model to include normal platelet counts. We combined data from three previous studies on 266 healthy individuals measuring impedance aggregometry with four agonists (collagen, adenosine diphosphate, thrombin receptor activating peptide-6, and ristocetin). Reduced platelet counts were established in vitro. The investigated platelet counts ranged from 26-425x10⁹/L. A positive linear correlation was found between platelet counts and platelet aggregation across normal and reduced platelet counts (all p-values <0.001). We established 95% prediction intervals for healthy platelet aggregation in relation to platelet count. The new expanded model serves as an optimized tool for evaluation of platelet aggregation at normal and reduced platelet counts.

BRAF V600E mutation detection in hairy cell leukemia-utility of archival DNA from bone marrow aspirate/imprint smear and amplification refractory mutation system

BRAF V600E is a disease defining mutation for hairy cell leukemia (HCL), which helps in its diagnosis and differentiation from morphologically similar splenic marginal zone lymphoma (SMZL) and HCL-variant (HCL-v). Forty eight cases:HCL(n = 34), SMZL(n = 11) and HCL-v(n = 3) were included. Of these, 32 were retrospective and 16 were prospective. DNA was extracted, in retrospective cases from cells obtained by smears from bone marrow aspirate/trephine imprint (BMA/BMTx) slides, and in prospective cases from peripheral blood (PB)/BMA samples. BRAF V600E mutation testing was done using ARMS-PCR. BRAF V600E mutation was positive in all HCL and negative in all SMZL and HCL-v cases. DNA extracted from BMA/BMTx slides gave results comparable to DNA extracted from PB/BMA samples. Median age of presentation for HCL (53 years) and SMZL (56 years) were quite similar, however, HCL-v (71 years) cases presented at an older age. Statistically significant differences between the three groups were seen for total leucocyte, platelet, absolute lymphocyte and monocyte counts, bone marrow-infiltration pattern, reticulin fibrosis, and an expression of CD11c, CD25, CD103, CD123, and CD200. The use of BMA/BMTx smears for DNA extraction was found to be a useful alternative to DNA extraction from formalin-fixed paraffin-embedded biopsy sections. ARMS-PCR is an efficient and specific technique to detect BRAF V600E mutation in HCL patients.

Predictor and Mid-Term Outcome of Clinically Significant Thrombocytopenia After Transcatheter Aortic Valve Selection

BACKGROUND

The frequency and predictors of thrombocytopenia after transcatheter aortic valve implantation (TAVI) are unclear.

METHODS AND RESULTS

This study enrolled 342 patients undergoing TAVI (245 with a percutaneous transfemoral approach, 65 with transfemoral surgical cutdown, and 32 with a non-transfemoral approach). Balloon-expandable and self-expanding valves were implanted in 235 and 107 patients, respectively. Platelet counts started to drop immediately, reaching a nadir 2-4 days after TAVI. Clinically significant thrombocytopenia (CSTP) was defined as a platelet count ≤50×109/L at the time of the nadir or both a platelet count between 80 and 51×109/L and a decrease in platelet count ≥50%. CSTP occurred in 16.7% patients. Approach site and TAVI valve selection significantly predicted CSTP. In multivariate analysis, independent predictors of CSTP were liver cirrhosis (odds ratio [OR] 7.22; 95% confidence interval [CI] 1.05-49.82), baseline platelet count ≤120×109/L (OR 2.98; 95% CI 1.20-7.38), multiple blood transfusions (OR 4.03; 95% CI 1.72-9.41), and the use of balloon-expandable valves (OR 2.38; 95% CI 1.04-5.46). Kaplan-Meier survival analysis with a generalized Wilcoxon test revealed that mid-term (2 years) mortality was greater for patients with than without CSTP (31.4% vs. 15.5%; P=0.008).

CONCLUSIONS

TAVI-related CSTP was not rare and was associated with poor mid-term outcomes. CSTP was not only caused by patients' comorbidities and TAVI complications, but also related to TAVI procedural factors.

The General Pediatrician's Guide to Isolated Thrombocytopenia

Platelets are an essential component of the hemostatic pathway; therefore, it is important to identify and diagnose patients with low platelet counts. This can be challenging, however, because thrombocytopenia can be relatively common and the differential diagnosis can be broad. Furthermore, because platelets can be affected both in form and function in a variety of medical conditions, platelet abnormalities can be the principal driver in some disorders but only a consequence in others. Critical factors in identifying the etiology of the thrombocytopenia include the severity and acuity of the patient's initial presentation along with the history, physical examination, and laboratory findings, all of which can provide important clues. The accurate diagnosis of thrombocytopenia is crucial for determining the appropriate management. This review highlights the key diagnostic considerations and recommended treatment when isolated thrombocytopenia is encountered in clinical practice. [Pediatr Ann. 2020;49(1):e27-e35.].

Acute thrombocytopenia: picking a way through a paucity of platelets

Thrombocytopenia is defined as a platelet count under 150x10⁹/litre. It may be found as a bystander to other pathology or directly related to an underlying haematological condition. Apart from laboratory artefact, it should be treated seriously as it often reflects serious underlying disease. This review uses short case histories to illustrate how to approach thrombocytopenia during the initial presentation of an adult patient to hospital. This article guides the general hospital physician through the narrow but potentially confusing differential diagnoses related to thrombocytopenia, with particular focus on immune thrombocytopenia, disseminated intravascular coagulation and thrombotic thrombocytopenic purpura. Thrombocytopenia in pregnancy deserves special consideration and will not be discussed in this article.

Peri-procedural thrombocytopenia after aortic bioprosthesis implant: A systematic review and meta-analysis comparison among conventional, stentless, rapid-deployment, and transcatheter valves

BACKGROUND

Thrombocytopenia has been shown to occur soon after surgical biological aortic valve replacement (AVR), and recently reported also after transcatheter valve implantation (TAVI). The mechanism underlying this phenomenon is still unknown, and its clinical impact on the peri-operative outcome has been poorly investigated.

METHODS

A systematic review and a meta-analysis of all available studies reporting data about peri-procedural thrombocytopenia on isolated bio-AVR, comparing rapid-deployment (RDV), stentless (stentless-AVR), and TAVI vs. stented (stented-AVR) valves, have been performed.

RESULTS

Fifteen trials (2.163 patients) were included in the meta-analysis. Perioperative platelet reduction ranged from 35% to 55% in stented-AVR, from 60% to 77% in stentless-AVR, from 53% to 60% in RDV, and from to 21% to 72% in TAVI (apparently, balloon-expandable valves more frequently associated to thrombocytopenia). Stented-AVR required more red blood cells transfusion than stentless-AVR (P < 0.0001), whereas no difference has been found between RDV and stented-AVR. Platelet transfusion rate was very low in all surgical groups. No difference has been found in RDV and stentless-AVR vs. stented-AVR, in terms of reoperation for bleeding, and length-of-intensive care unit or hospital stay.

CONCLUSIONS

Thrombocytopenia-related major adverse events were mainly reported in TAVI patients, whereas clinically meaningless in surgical patients. Transient peri-procedural thrombocytopenia is common after bio-AVR, regardless of prosthesis's type or implant modality. It should receive appropriate monitoring and focused investigations.

The use of mean platelet volume for distinguishing the causes of thrombocytopenia in adult patients

Establishment and analysis of mean platelet volume (MPV) may be helpful in the discrimination between underproduction or over-destruction of platelets as the causes of thrombocytopenia. The primary objective is to find the cut-off point of MPV for distinguishing causes of thrombocytopenia. The secondary objective is to validate the cut-off value of the MPV by using bone marrow examination. Thrombocytopenic patients were enrolled in a training set and a receiving operating characteristics (ROC) curve was plotted to obtain the cut-off value of MPV. A validation set of patients was recruited to validate the cut-off value. The training set included 240 patients. Half with with underproductive (n=120) and half with over-destructive thrombocytopenia (n=120). The best cut-off value of MPV was 8.8 fL. The validation set included 119 patients in total, again in 2 groups, those with underproductive (n=84) and those with overdestructive thrombocytopenia (n=35). The sensitivity, specificity, PPV and NPV when MPV ≥8.8 fL indicating over-destructive thrombocytopenia were 77%, 89%, 89% and 77%, respectively. MPV is useful for differentiating the cause of thrombocytopenia. The value of MPV ≥8.8 fL has acceptable sensitivity and specificity for diagnosis of over-destructive thrombocytopenia.

Management of immune thrombocytopenia in elderly patients

Despite the improvement in understanding its pathogenesis and the introduction of novel treatment options, the management of primary immune thrombocytopenia (ITP) still remains challenging. Considering its increased incidence with aging and prolonged life-expectancy, ITP is often diagnosed in elderly patients, a subset that deserves some special precautions. Ensure the diagnosis is a crucial step, and carefully attention must be given in excluding other causes of thrombocytopenia, especially among older people that frequently suffer from many comorbidities. When it comes to treatment decision, it is worth keeping into account that the elderly have an increased risk of bleeding, thrombosis and infections, that they often require many concomitant therapies, including antiplatelet or anticoagulant agents, and that treatment-related toxicities are often increased and sometimes more dangerous that the disease itself. There are not dedicated guidelines, and only few specific studies. Steroids with or without IVIG remain the first-line treatment. Splenectomy is less effective than in youngers and burdened by an increased thrombotic and infectious risk. Rituximab is a good option in non-immunocompromised patients, but long-term remissions are few. Eltrombopag and romiplostim have a good safety and efficacy profile, and have become a prominent drug in this subset, even if they are associated with a possible increased risk of thrombosis, and long-term toxicity is unknown. Other drugs, such as dapsone and danazol, have a well-known efficacy and safety profile, and still represent a valid option among elderly patients.

How do we diagnose immune thrombocytopenia in 2018?

In this report, we will review the various clinical and laboratory approaches to diagnosing immune thrombocytopenia (ITP), with a focus on its laboratory diagnosis. We will also summarize the results from a number of laboratories that have applied techniques to detect anti-platelet autoantibodies as diagnostic tests for ITP. Although there is considerable variability in methods among laboratories, there is general agreement that platelet autoantibody testing has a high specificity but low sensitivity. This suggests several possibilities: (1) the ideal test for ITP has yet to be developed, (2) current test methods need to be improved, or (3) ITP is the clinical expression of a variety of thrombocytopenic disorders with different underlying mechanisms. Even the clinical diagnosis of ITP is complex, and experienced clinicians do not always agree on whether a particular patient has ITP. Improvements in the diagnostic approach to ITP are necessary to improve the management of this disorder.

Platelet to lymphocyte ratio is associated with the current activity of ANCA-associated vasculitis at diagnosis: a retrospective monocentric study

Platelet to lymphocyte ratio (PLR) has been introduced as a useful index to estimate the current inflammatory burdens in various diseases. In this study, we investigate whether PLR is associated with the severity of ANCA-associated vasculitis (AAV). We retrospectively reviewed the medical records of 163 patients with AAV, collected clinical, laboratory and radiological data and calculated Birmingham vasculitis activity score (BVAS). We defined the lower limit of the highest tertile of BVAS as the cut-off for severe AAV (BVAS ≥ 16). The optimal cut-off of PLR for severe AAV was set as 272.0. The odds ratio (OR) of PLR for severe AAV was assessed using the univariable and multivariable logistic regression analyses. The median age at diagnosis was 58.0 years and 51 patients (31.3%) were men. Patients with severe AAV exhibited higher rate of ANCA positivity and higher blood urea nitrogen (BUN), creatinine (Cr), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) than those without. Patients with severe AAV exhibited significantly increased median PLR compared to those without (299.3 vs. 184.0). In the univariable binary logistic regression analysis, BUN ≥ 17.45 mg/dL (OR 3.730), Cr ≥ 1.12 mg/dL (OR 3.519), ESR ≥ 83.5 mm/h (OR 2.785), CRP ≥ 20.0 mg/L (OR 2.612), PLR ≥ 272.0 (OR 4.231) and ANCA positivity (OR 2.306) were associated with severe AAV. In the multivariable binary logistic regression analysis, only PLR ≥ 272.0 was an independent predictor of severe AAV at diagnosis (OR 2.734, 95% CI 1.247, 5.993). In conclusion, PLR at diagnosis is associated with the current activity of vasculitis in AAV patients.

Spontaneous bleeding in thrombocytopenia: Is it really spontaneous?

Spontaneous bleeding is a clinical hallmark of thrombocytopenia and can take multiple forms including petechiae, epistaxis, gum bleeding, or, in worst cases, intracranial hemorrhage. Those bleeding events are called " spontaneous " because they occur in the absence of overt trauma. Spontaneous bleeding manifestations have long been considered to be a direct consequence of low platelet counts. Nevertheless, although low platelet counts may lead to ultrastructural endothelial alterations, those alterations and the associated state of vascular fragility are unlikely sufficient to cause spontaneous rupture of the microvessel wall. Indeed, in addition to endothelial injury, factors capable of damaging the basement membrane are required to allow escape of red blood cells in the extravascular space. Therefore, despite their misleading name, spontaneous bleeding events in thrombocytopenia are most likely provoked and involve subclinical biological processes in which platelets normally intervene to ensure hemostasis. In this review, we discuss past and more recent studies on the possible triggers of spontaneous bleeding events in thrombocytopenia, with a particular focus on the role of inflammatory reactions.

My patient is thrombocytopenic! Is (s)he? Why? And what shall I do?

Solving the riddle of a thrombocytopenic patient is a difficult and fascinating task. The spectrum of possible aetiologies is wide, ranging from an in vitro artefact to severe treatment-resistant thrombocytopenic bleeding conditions, or even life-threatening prothrombotic states. Moreover, thrombocytopenia by itself does not protect from thrombosis and sometimes a patient with a low platelet count requires concomitant antithrombotic treatment as well. In order to identify and treat the cause and the effects of the thrombocytopenia, you have to put together several pieces of information, solving a unique jig-jaw puzzle.

The present work is not a textbook article about thrombocytopenia, rather a collection of differential diagnostic thoughts, treatment concepts, and some basic knowledge, that you can retrieve when facing your next thrombocytopenic patient. Enjoy reading it, but most importantly enjoy taking care of patients with a low platelet count. I bet the present work will assist you in this challenging and rewarding clinical task.

Implementation of a rapid HIT immunoassay at a university hospital - Retrospective analysis of HIT laboratory orders in patients with thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a rare cause of thrombocytopenia and a potentially life-threatening adverse drug reaction. Clinical overdiagnosis of HIT results in costly laboratory tests and anticoagulation. Criteria and algorithms for diagnosis are established, but their translation into clinical practice is still challenging.

STUDY DESIGN AND METHODS

In a retrospective approach we studied all HIT related laboratory test requests within four years and evaluated data before (1st period, 24month) and after (2nd period, 24month) replacing particle gel immunoassay (PaGIA) and enzyme-linked immunosorbent assay (ELISA) by a chemiluminescent immunoassay (CLIA). HIT was confirmed by heparin-induced platelet activation (HIPA) test. Clinical pretest probability for HIT using an implemented simplified 4Ts score and platelet count were evaluated. Costs for laboratory tests and alternative anticoagulation were calculated.

RESULTS

In 1850 patients with suspected HIT, 2327 laboratory orders were performed. In 87.2% of these orders an intermediate/high simplified 4Ts score was found. Thrombocytopenia was present in 87.1%. After replacing PaGIA and ELISA by CLIA the number of immunological and functional laboratory tests was reduced by 38.2%. The number of positive HIT immunoassays declined from 22.6% to 6.0%, while the number of positive HIPA tests among positive immunological tests increased by 19%. Altogether, acute HIT was confirmed in 59 patients. A decline in the use of alternative anticoagulants was observed in the 2nd period.

CONCLUSION

Our study shows that in a university hospital setting HIT is well-known, but diagnosis requires a precise laboratory confirmation. Replacing PaGIA and ELISA by CLIA did not influence laboratory order behavior but results in reduced overall costs for laboratory diagnostics and alternative anticoagulation.

Effect of radiation-induced endothelial cell injury on platelet regeneration by megakaryocytes

Thrombocytopenia is an important cause of hemorrhage and death after radiation injury, but the pathogenesis of radiation-induced thrombocytopenia has not been fully characterized. Here, we investigated the influence of radiation-induced endothelial cell injury on platelet regeneration. We found that human umbilical vein endothelial cells (HUVECs) underwent a high rate of apoptosis, accompanied by a significant reduction in the expression of vascular endothelial growth factor (VEGF) at 96 h after radiation. Subsequent investigations revealed that radiation injury lowered the ability of HUVECs to attract migrating megakaryocytes (MKs). Moreover, the adhesion of MKs to HUVECs was markedly reduced when HUVECs were exposed to radiation, accompanied by a decreased production of platelets by MKs. In vivo study showed that VEGF treatment significantly promoted the migration of MKs into the vascular niche and accelerated platelet recovery in irradiated mice. Our studies demonstrate that endothelial cell injury contributes to the slow recovery of platelets after radiation, which provides a deeper insight into the pathogenesis of thrombocytopenia induced by radiation.