Thrombocytosis and thrombocythemia

Thromboinflammatory challenges in stroke pathophysiology

Despite years of encouraging translational research, ischemic stroke still remains as one of the highest unmet medical needs nowadays, causing a tremendous burden to health care systems worldwide. Following an ischemic insult, a complex signaling pathway emerges leading to highly interconnected thrombotic as well as neuroinflammatory signatures, the so-called thromboinflammatory cascade. Here, we thoroughly review the cell-specific and time-dependent role of different immune cell types, i.e., neutrophils, macrophages, T and B cells, as key thromboinflammatory mediators modulating the neuroinflammatory response upon stroke. Similarly, the relevance of platelets and their tight crosstalk with a variety of immune cells highlights the relevance of this cell-cell interaction during microvascular dysfunction, neovascularization, and cellular adhesion. Ultimately, we provide an up-to-date overview of therapeutic approaches mechanistically targeting thromboinflammation currently under clinical translation, especially focusing on phase I to III clinical trials.

Neutrophil to lymphocyte ratio and platelet to lymphocyte ratio as prognostic predictors for delirium in critically ill patients: a systematic review and meta-analysis

INTRODUCTION

In this systematic review and meta-analysis, we aim to analyze the current literature to evaluate neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) values among critically ill patients who develop delirium as compared to those who do not.

METHODS

PubMed, Web of Science, and Scopus were used to conduct a systematic search for relevant publications published before June 12, 2022. The Newcastle-Ottawa scale was used for quality assessment. Because a significant level of heterogeneity was found, we used the random-effects model to generate pooled effects.

RESULTS

Twenty-four studies including 11,579 critically ill patients, of whom 2439 were diagnosed with delirium, were included in our meta-analysis. Compared with the non-delirious group, the delirious group's NLR levels were significantly higher (WMD = 2.14; CI 95% = 1.48-2.80, p < 0.01). In the subgroup analysis according to the type of critical condition, the NLR levels in patients of delirious group were significantly more than those of non-delirious group in studies on POD, PSD and PCD (WMD = 1.14, CI 95% = 0.38-1.91, p < 0.01, WMD = 1.38, CI 95% = 1.04-1.72, p < 0.001, and WMD = 4.22, CI 95% = 3.47-4.98, p < 0.001, respectively). However, compared with the non-delirious group, the delirious group's PLR levels were not significantly different (WMD = 1.74; CI 95% = -12.39-15.86, p = 0.80).

CONCLUSION

Our findings support NLR to be a promising biomarker that can be readily integrated into clinical settings to aid in the prediction and prevention of delirium.

Evaluation of Minimal Optimal Dose of Intravenous Ferric Carboxymaltose for Treatment of Iron Deficiency Anemia and Risk of Transient Hyperferritinemia

BACKGROUND

Iron supplementation is administered orally or intravenously to treat iron-deficiency anemia (IDA). Ferric Carboxymaltose (FCM) "Ferinject®" is an intravenous (IV) iron preparation that has emerged as a safe therapeutic option for treating IDA in the past decade.

AIM

This study aimed to evaluate safety and efficacy of carboxymaltose in a cohort of patients with IDA not responding to oral therapy.

METHODS

This 12-month retrospective study included 106 patients with IDA, with-or without bariatric surgery, who received (single or multiple doses) of Carboxymaltose 500mg/10mL. Data points included patients' demographics, baseline data for Hb, platelet, ferritin, and MCV pre-and at 1, 2, and 3 months following different doses of IV-Carboxymaltose. Changes in Hb, MCV, platelets, and ferritin levels were recorded in response to Carboxymaltose to assess the optimal dose, risk of hyperferritinemia, and hypophosphatemia.

RESULTS

At three months (95 days) follow-up, the median change pre-and post-therapy in hemoglobin was from 9.5 to 11.9g/dL (p < 0.01), MCV 73.6-80.5fL (p < 0.01), and ferritin 5.3-93.8ng/mL. A significant difference was observed between platelet count of patients who underwent bariatric surgery and those who did not. An optimal ferritin response (>30ng/mL) was observed in 87.8% of patients who received first dose, and none of the full three doses showed no response. 37% of patients who received two doses developed hyperferritinemia. Serum phosphate levels were assessed in 28 cases, and hypophosphatemia was observed in 25% of these patients.

CONCLUSION

Carboxymaltose is a reliable option for IDA. IV-FCM therapy helps achieve significant improvement in hemoglobin concentration and MCV from the first dose carrying a low reversible risk of hyperferritinemia following multiple doses. An interesting finding of this study is the discovery of a population of IDA patients requiring periodic assessment for iron reinfusion to sustain normal levels, mostly post-bariatric surgery. Changes in serum phosphate levels reported to occur consecutively with FCM treatment should be further studied.

Therapeutic Plateletpheresis in Patients With Thrombocytosis: Gender, Hemoglobin Before Apheresis Significantly Affect Collection Efficiency

Background: Thrombocytosis is a common symptom in myeloproliferative neoplasms (MPN), and excessive proliferation may deteriorate into thrombosis, bleeding, myelofibrosis, and may ultimately convert to acute leukemia. This study aimed to investigate the collection efficiency of plateletpheresis (CEPP) and factors influencing its efficacy in patients with thrombocytosis.

Materials and Methods: From September 2010 to December 2016, 81 patients from two institutions in China with myeloproliferative neoplasms and thrombocytosis accompanied by severe symptoms were treated with plateletpheresis by Fresenius COM. TEC machine.

Results: After apheresis, the median CEPP was 20.71% (IQR: 9.99–36.69%) and median PLT reduction rate was 25.87% (IQR: 21.78–36.23%). Further analysis showed that no significant difference was observed between PLT count with 800–1,000 × 10⁹/L and > 1,000 × 10⁹/L. The PLT counts significantly decreased (P < 0.001) after plateletpheresis, the red blood cell (RBC), white blood cell (WBC), hemoglobin (HGB), and hematocrit (HCT) levels showed no significant differences before- or after- plateletpheresis. Multivariate analysis showed that female sex (P = 0.009) and HGB (P = 0.010) before apheresis were associated with CEPP. Female (P = 0.022), HCT (P = 0.001) and blood volume (P = 0.015) were associated with the PLT reduction rate. Furthermore, symptoms were relieved after apheresis in patients whose PLT count was 800–1,000 × 10⁹/L accompanied with symptoms.

Conclusions: It is reasonable to perform plateletpheresis when the PLT count is over 800 × 10⁹/L and patients are complicated by clinical symptoms such as dizziness, headache, somnolence, and stupor. Plateletpheresis is effective in removing PLTs especially in females with high HGB.

Rapid Cytoreduction by Plateletapheresis in the Treatment of Thrombocythemia

The objective of this chapter is to provide a systematic overview of current knowledge regarding therapeutic apheresis—primarily therapeutic plateletapheresis (TP)—and to summarize evidence-based practical approaches related to cytapheresis treatment of “hyperthrombocytosis” or “extreme thrombocytosis” (ETC). Our results of platelet (Plt) quantitative/qualitative analyses and evaluation of efficacy of apheresis systems/devices—on the basis of Plt removal and in vivo Plt depletion—will be presented. Our preclinical researches confirmed that in Plt concentrates, the initial ratio of discoid shapes was 70%, spherical 20%, and less valuable (dendritic/balloonized) shapes 10%—with morphological score of platelets (MSP = 300–400). After storage, the ratio of discoid and spherical shapes was decreased, while the less valuable ones progressively increased (MSP = 200). Electron microscopy has shown discoid shapes with typical ultrastructural properties. Spherical shapes with reduced electron density and peripheral location of granules/organelles were detected. Also, dendritic shapes with cytoskeletal “rearrangement,” membrane system integrity damages, and pseudopodia formations were documented. Our clinical study demonstrated that TP was useful in ETC treatment and should help prevention of “thrombo-hemorrhagic” events—until chemotherapy, antiplatelet drugs, and other medication take effect. During TP treatment, Plt count and morphology/ultrastructure were examined. Plt functions by multiplate analyzer were evaluated. We concluded that intensive TP was an effective, safe, and rapid cytoreductive treatment for ET.

Therapeutic thrombocytapheresis in myeloproliferative neoplasms: A single-institution experience

Thrombocytosis is usually seen in myeloproliferative neoplasms (MPNs) and associated with thrombohemorrhagic complications. Therapeutic thrombocytapheresis using an automatic cell separator can help to achieve prompt platelet count reduction to decrease the rate of thrombotic events. In this study, we report a single center's experience in managing MPN patients with thrombocytapheresis prior to chemotherapy. Thrombocytapheresis procedures were performed in 185 MPN patients with thrombocytosis between January 2016 and June 2017. The median percentage reduction of platelets was 44.5% and the median percentage removal efficiency was 65.2% for 83 procedures where the waste bag was sampled. Procedures were generally well tolerated with few patients having mild adverse events (13 out of 185 patients).

Clinical course and short-term outcome of postsplenectomy reactive thrombocytosis in children without myeloproliferative disorders: A single institutional experience from a developing country

OBJECTIVES

To evaluate the clinical outcome and complications in the pediatric population who had splenectomy at our institution, emphasizing the incidence of postplenectomy reactive thrombocytosis (RT) and its clinical significance in children without underlying hematological malignancies.

MATERIALS AND METHODS

The medical records of pediatric patients undergoing splenectomy were retrospectively reviewed for the period 1999-2018. The following variables were analyzed: Demographic parameters (age, sex), indications for surgery, operative procedures, preoperative and postoperative platelet count (postplenectomy RT), the use of anticoagulant therapy, and postoperative complications. The patients were divided into two groups according to indications for splenectomy: The non-neoplastic hematology group and the non-hematology group (splenectomy for trauma or other spleen non-hematological pathology).

RESULTS

Fifty-two pediatric (37 male and 15 female) patients who underwent splenectomy at our institution were reviewed. Thirty-four patients (65%) were in the non-hematological group (splenic rupture, cysts, and abscess) and 18 patients (35%) in the non-neoplastic hematological group (hereditary spherocytosis and immune thrombocytopenia). The two groups did not differ significantly in regards to the patients' age, sex, and preoperative platelet count (P>0.05 for all variables). Forty-nine patients (94.2%) developed postplenectomy RT. The percentages of mild, moderate and extreme thrombocytosis were 48.9%, 30.7%, and 20.4%, respectively. The comparisons of RT patients between the non-neoplastic hematology and the non-hematology group revealed no significant differences in regards to the patients' age, sex, preoperative and postoperative platelet counts, preoperative and postoperative leukocyte counts, and the average length of hospital stay (P>0.05 for all variables). None of the patients from the cohort was affected by any thrombotic or hemorrhagic complications.

CONCLUSIONS

We confirm that RT is a very common event following splenectomy, but in this study it was not associated with clinically evident thrombotic or hemorrhagic complications in children undergoing splenectomy for trauma, structural lesions or non-neoplastic hematological disorders.

Platelet Function Tests and Inflammatory Markers for the Differentiation of Primary Thrombocytosis and Secondary Thrombocytosis

Background:

The prognosis and management of primary thrombocytosis (PT) and secondary thrombocytosis (ST) are different. This study aims to evaluate the role of platelet function tests by light transmission platelet aggregometry (LTA), plasma von Willebrand factor antigen (vWF:Ag), ristocetin cofactor activity (vWF:RCo) and inflammatory markers [erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)] for the differentiation between PT and ST.

Methods:

This prospective study was carried out in patients with platelet counts greater than 450 x 109/L. Primary outcomes were the sensitivity and specificity of platelet function tests by LTA for the differentiation of PT and ST. Secondary outcomes were sensitivity and specificity of ESR, CRP, vWF:Ag, and vWF:RCo for the differentiation of PT and ST.

Results:

Fifty-two patients were enrolled onto the study of which 26 (50%) had PT. The sensitivity and specificity of epinephrine, collagen, and arachidonic acid (AA) induced abnormal LTA for the differentiation of PT from ST were sensitivity of 50%, 38.5%, 26.9% and specificity of 88.5%, 100%, 100% respectively. The sensitivity and specificity of abnormal ESR, CRP, and either abnormal ESR or CRP in the differentiation of ST from PT were sensitivity of 88.5%, 80.8%, 100% and specificity of 65.4%, 61.5%, 46.2% respectively. The sensitivity and specificity of low vWF:Ag and vWF:RCo in the differentiation of PT from ST were sensitivity of 7.69%, 42.3% and specificity of 100%, 88.5% respectively.

Conclusions:

Abnormal platelet function determined by LTA with collagen, AA, epinephrine had high specificity ratings enabling the differentiation between PT and ST. vWF:RCo, ESR and CRP levels could be helpful in differentiating between PT and ST.

A prospective evaluation of rivaroxaban on haemostatic parameters in apparently healthy dogs

The purpose of this study was to determine the effect of rivaroxaban (RIV) on haemostatic parameters assessed by prothrombin time (PT), activated partial thromboplastin time (aPTT) and kaolin‐activated thromboelastography (TEG) in apparently healthy dogs administered 1 mg kg⁻¹ orally once daily for 1 week. Eleven dogs had a baseline complete blood count (CBC), fibrinogen, platelet count, serum chemistry profile, PT, aPTT, and TEG performed. Each dog was then administered approximately 1.0 mg kg⁻¹ of RIV orally once daily for 1 week and the CBC, fibrinogen, platelet count, serum chemistry profile, PT, aPTT, and TEG was re‐evaluated. Any side effects attributed to RIV were noted at this time. One dog was excluded due to identification of a macrocytic thrombocytopenia on pre‐treatment blood work. The remaining 10 enrolled dogs completed the study. Dogs received a median dose of 1.02 mg kg⁻¹ (range 0.94–1.17 mg kg⁻¹) of RIV once daily and was associated with a significant increase in pulse, packed cell volume, total solids, platelet count, fibrinogen and a significant decrease in mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. There was no significant change in PT, aPTT or any TEG parameters. The RIV appeared well tolerated with one dog having one episode of vomiting on day 4 but otherwise no other side effects were identified clinically or on recheck blood work. The results of this study suggests that RIV at a dose of 1 mg kg⁻¹ orally once daily is safe and well tolerated but does not cause a significant prolongation of PT, aPTT or TEG parameters.

High energy injury is a risk factor for preoperative venous thromboembolism in the patients with hip fractures: A prospective observational study

BACKGROUND

The purpose of this study was to identify the incidence of preoperative venous thromboembolism (VTE), and determine if high energy hip fracture affects preoperative VTE occurrence.

METHODS

Three-hundred nine patients (244 low and 61 high energy injuries) treated between March 2015 and March 2017 were included in this study. Indirect multidetector computed tomographic venography for the detection of preoperative VTE was performed at admission. The incidence of preoperative VTE was compared between high and low energy injury hip fractures. Logistic regression analysis was used to identify independent risk factors for preoperative VTE.

RESULTS

The overall incidence of preoperative VTE was 18.4% (56 of 305 patients). Preoperative VTE was identified in 17 (27.9%) and 39 (16.0%) patients in the high and low energy injury groups, respectively (p = 0.034). Multivariate logistic regression analysis showed that high energy injury, history of VTE, and myeloproliferative disease were significant predictive factors of preoperative VTE (OR = 2.451; 95% CI = 1.227-4.896, OR = 11.174; 95% CI = 3.500-35.673, OR = 6.936; 95% CI = 1.641-29.321, respectively) CONCLUSION: Because high energy hip fracture is significantly associated with preoperative VTE occurrence, preoperative evaluation and proper thromboprophylaxis should be performed for patients with a high-energy hip fracture.

Preoperative Platelet Count Predicts Lower Extremity Free Flap Thrombosis: A Multi-Institutional Experience

BACKGROUND

Thrombocytosis in patients undergoing lower extremity free tissue transfer may be associated with increased risk of microvascular complications. This study assessed whether preoperative platelet counts predict lower extremity free flap thrombosis.

METHODS

All patients undergoing lower extremity free tissue transfer at Duke University from 1997 to 2013 and at the University of Pennsylvania from 2002 to 2013 were retrospectively identified. Logistic regression was used to assess whether preoperative platelet counts independently predict flap thrombosis, controlling for baseline and operative factors.

RESULTS

A total of 565 patients underwent lower extremity free tissue transfer, with an overall flap thrombosis rate of 16 percent (n = 91). Elevated preoperative platelet counts were independently associated with both intraoperative thrombosis (500 ± 120 versus 316 ± 144 × 10/liter; p < 0.001) and postoperative thrombosis (410 ± 183 versus 320 ± 143 × 10/liter; p = 0.040) in 215 patients who sustained acute lower extremity trauma within 30 days before reconstruction. In acute trauma patients, preoperative platelet counts predicted a four-fold increased risk of intraoperative thrombosis (cutoff value, 403 × 10/liter; OR, 4.08; p < 0.001) and a two-fold increased risk of postoperative thrombosis (cutoff value, 361 × 10/liter; OR, 2.16; p = 0.005). In patients who did not sustain acute trauma, preoperative platelet counts predicted a four-fold increased risk of intraoperative thrombosis (cutoff value, 352 × 10/liter; OR, 3.82; p = 0.002).

CONCLUSIONS

Acute trauma patients with elevated preoperative platelet counts are at increased risk for lower extremity free flap complications. Prospective evaluation is warranted for guiding risk stratification and targeted treatment strategies.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Ertapenem-Induced Thrombocytosis

Ertapenem is a β-lactam antibiotic that has a broad spectrum of anti-microbial coverage. Hematological adverse events like thrombocytosis, neutropenia, and neutropenia are infrequent. Here we report a rare case of drug-induced thrombocytosis in a 68-year-old female, who was treated with ertapenem for the diagnosis of complicated abdominal infection. This case emphasizes that any patient with thrombocytosis should be assessed with a careful and detailed history with consideration for possible drug side effects.

The role of thrombocytapheresis in the contemporary management of hyperthrombocytosis in myeloproliferative neoplasms: A case-based review

Extreme thrombocytosis induces an acquired thrombotic-hemorrhagic diathesis, and left uncontrolled is a harbinger of potentially fatal vascular complications. Currently, cytoreduction with medical therapy remains the mainstay of hyperthrombocytosis management. However, it offers a less-than-ideal option in situations where a rapid reduction in platelets is urgently needed, as in the presence of vital end-organ ischemia or to ameliorate of life-threatening hemorrhage. The role of thrombocytapheresis, or plateletpheresis, in hyperthrombocytosis has become increasingly obsolete given the proactive titration of cytoreductive therapies and early identification and correction of reversible causes of reactive thrombocytosis. Despite its narrowed indications, plateletpheresis continues to offer a valuable temporizing measure in platelet count reduction before cytoreductive agents exert their maximal effect. In this context, it is important for the treating physician to be aware of the symptoms and risks associated with hyperthrombocytosis to inform best clinical practices. In this review, we discuss the role of plateletpheresis in the modern-day management of hyperthrombocytosis in patients with myeloproliferative neoplasms through a case based review of the literature. It becomes apparent throughout the discussion that the decision to perform plateletpheresis should be individualized based upon the clinical scenario, degree of thrombocytosis, available infrastructure and every patient's risk profile.

Surgery for massive splenomegaly

BACKGROUND

Splenectomy for massive splenomegaly (spleen weight more than 1·5 kg) is commonly believed to be hazardous and to provide poor palliation. The aim of this cohort study was to investigate these issues and examine the many definitions of massive splenomegaly to see whether a better tool might be proposed for preoperative evaluation of these patients.

METHODS

Morbidity and long-term outcomes were assessed in consecutive patients. Relief of pressure-volume-related symptoms and sustainable independence from transfusion in patients were used to ascertain the impact of splenectomy.

RESULTS

Splenectomy was performed in 56 patients, mainly for non-Hodgkin's lymphoma and myeloproliferative diseases. Median spleen weight was 2·3 (range 1·5-6·0) kg. Mortality at 180 days was zero, and the postoperative complication rate was 25 per cent (17 complications in 14 patients). At 2 years, relief of pain was maintained in 33 of 34 patients, with sustained independence from transfusion in 15 of 19 patients with anaemia and nine of 11 with thrombocytopenia. Spleen weight correlated negatively with BMI (P = 0·036).

CONCLUSION

Splenectomy for massive splenomegaly is safe and provides effective palliation. Provisional cut-off points relating to spleen size and BMI help to identify patients benefiting from a splenectomy, even those in a critical state.

Red Blood Cell Distribution Width and the Platelet Count in Iron-deficient Children Aged 0.5-3 Years

Early detection of iron deficiency (ID) and iron deficiency anemia (IDA) in young children is important to prevent impaired neurodevelopment. Unfortunately, many biomarkers of ID are influenced by infection, thus limiting their usefulness. The aim of this study was to investigate the value of red blood cell distribution width (RDW) and the platelet count for detecting ID(A) among otherwise healthy children. A multicenter prospective observational study was conducted in the Netherlands to investigate the prevalence of ID(A) in 400 healthy children aged 0.5-3 years. ID was defined as serum ferritin (SF) <12 μg/L in the absence of infection (C-reactive protein [CRP] <5 mg/L) and IDA as hemoglobin <110 g/L combined with ID. RDW (%) and the platelet count were determined in the complete blood cell count. RDW was inversely correlated with SF and not associated with CRP. Calculated cutoff values for RDW to detect ID and IDA gave a relatively low sensitivity (53.1% and 57.1%, respectively) and specificity (64.7% and 69.9%, respectively). Anemic children with a RDW >14.3% had a 2.7 higher odds (95% confidence interval [CI]: 1.2-6.3) to be iron deficient, compared with anemic children with a RDW <14.3%. The platelet count showed a large range in both ID and non-ID children. In conclusion, RDW can be helpful for identifying ID as the cause of anemia in 0.5- to 3-year-old children, but not as primary biomarker of ID(A). RDW values are not influenced by the presence of infection. There appears to be no role for the platelet count in diagnosing ID(A) in this group of children.

Association between secondary thrombocytosis and viral respiratory tract infections in children

Secondary thrombocytosis (ST) is frequently observed in children with a variety of clinical conditions. The leading cause of ST is respiratory tract infection (RTI) in children. Nasopharyngeal aspirate samples were collected and assessed for common respiratory viruses. The relationships between virus infections and secondary thrombocytosis were analyzed retrospectively. The blood platelet count and the presence of respiratory viruses were determined for 3156 RTI patients, and 817 (25.9%) cases with platelet ≥500 × 10(9)/L were considered as the thrombocytosis group. Compared with the normal group, the detection rates of respiratory syncytial virus (RSV) and human rhinovirus (HRV) were significantly higher in the thrombocytosis group (P = 0.017 and 0.042, respectively). HRV single infection was a risk factor associated with thrombocytosis [odds ratio (OR) = 1.560, 95% confidence interval (CI) = 1.108-2.197]. Furthermore, ST was more likely to occur in younger patients who had clinical manifestations of wheezing and dyspnea and who had been diagnosed with bronchiolitis. Furthermore, the course of disease lasted longer in these patients. ST is associated with viral respiratory tract infections, especially RSV and HRV infections. HRV single infection is a risk factor associated with thrombocytosis.

Methodological challenges in utilizing miRNAs as circulating biomarkers

MicroRNAs (miRNAs) have emerged as important regulators in the post-transcriptional control of gene expression. The discovery of their presence not only in tissues but also in extratissular fluids, including blood, urine and cerebro-spinal fluid, together with their changes in expression in various pathological conditions, has implicated these extracellular miRNAs as informative biomarkers of disease. However, exploiting miRNAs in this capacity requires methodological rigour. Here, we report several key procedural aspects of miRNA isolation from plasma and serum, as exemplified by research in cardiovascular and pulmonary diseases. We also highlight the advantages and disadvantages of various profiling methods to determine the expression levels of plasma- and serum-derived miRNAs. Attention to such methodological details is critical, as circulating miRNAs become diagnostic tools for various human diseases.

Activation of Janus kinase/signal transducers and activators of transcription pathway involved in megakaryocyte proliferation induced by vanadium resembles some aspects of essential thrombocythemia

Vanadium (V) is an air pollutant released into the atmosphere by burning fossil fuels. Also, it has been recently evaluated for their carcinogenic potential to establish permissible limits of exposure at workplaces. We previously reported an increase in the number and size of platelets and their precursor cells and megakaryocytes in bone marrow and spleen. The aim of this study was to identify the involvement of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway and thrombopoietin (TPO) receptor, and myeloproliferative leukemia virus oncogene (Mpl), in megakaryocyte proliferation induced by this compound. Mice were exposed twice a week to vanadium pentoxide inhalation (0.02 M) and were killed at 4th, 6th, and 8th week of exposure. Phosphorylated JAK2 (JAK2 ph), STAT3 (STAT3 ph), STAT5, and Mpl were identified in mice spleen megakaryocytes by cytofluorometry and immunohistochemistry. An increase in JAK2 ph and STAT3 ph, but a decrease in Mpl at 8-week exposure was identified in our findings. Taking together, we propose that the morphological findings, JAK/STAT activation, and decreased Mpl receptor induced by V leads to a condition comparable to essential thrombocythemia, so the effect on megakaryocytes caused by different mechanisms is similar. We also suggest that the decrease in Mpl is a negative feedback mechanism after the JAK/STAT activation. Since megakaryocytes are platelet precursors, their alteration affects platelet morphology and function, which might have implications in hemostasis as demonstrated previously, so it is important to continue evaluating the effects of toxics and pollutants on megakaryocytes and platelets.

Two cases of pediatric essential thrombocythemia managed effectively with hydroxyurea

Thrombocytosis is common in infancy and childhood. Essential thrombocythemia (ET), a myeloproliferative disorder, is a much less common cause of thrombocytosis in childhood. We report two cases of essential thrombocythemia in 5- and 10-year-old children, who presented with platelet counts of more than 1,000,000/mm(3). Treatment is not recommended for ET in an asymptomatic patient in the absence of bleeding or thrombosis and a platelet count <1,500,000/mm(3). Our first case had platelets >1,500,000/mm(3), and a second child was symptomatic with recurrent headache. Both responded well to therapy with hydroxyurea (dose 15-30 mg/kg/day) and tolerated it well.

Examination of the Relationship Between Antimicrobials and Thrombocytosis

Objective:

To evaluate whether there is a relationship between antimicrobial therapy and the development of thrombocytosis.

Data Sources:

Literature was accessed through EMBASE (1977-June 2012) and MEDLINE (1977-June 2012) using the terms thrombocytosis and antimicrobial. In addition, reference citations from publications identified were reviewed.

Study Selection and Data Extraction:

All English-language publications identified were evaluated. For case reports, the Naranjo probability scale was used to calculate the likelihood of the drug causing the reaction.

Data Synthesis:

Thrombocytosis occurring during antimicrobial therapy is well documented, with several case reports and clinical trial observations. However, a direct causal relationship is not yet supported by the available literature. Platelets are welt known to be an acute phase reactant, with an elevated count occurring after acute conditions such as blood loss, inflammation, or infection. Thrombocytosis during antimicrobial therapy may be the result of an infectious process and not an adverse drug event.

Conclusions:

Based on the current available literature, a definitive link cannot be established between antimicrobial therapy and occurrence of thrombocytosis.

Reactive thrombocytosis and risk of subsequent venous thromboembolism: a cohort study

BACKGROUND

It is uncertain whether reactive thrombocytosis is associated with an increased risk of venous thromboembolism. This study assessed the incidence of reactive thrombocytosis, defined as platelet count ≥ 500 × 10(9)  L(-1) , at intensive care unit discharge and its association with subsequent venous thromboembolism.

METHODS AND RESULTS

This cohort study involved linkage of routinely collected intensive care unit, laboratory, radiology and death registry data of critically ill patients admitted to the intensive care unit between January 2009 and March 2010. The census date for survival and radiologically confirmed venous thromboembolism was 31 October 2011. Of the 1446 patients who survived to intensive care unit discharge, 139 patients had reactive thrombocytosis (9.6%, 95% confidence interval [CI] 8.2-11.2%). Twenty-nine patients developed venous thromboembolism after discharge (2%, 95% CI 1.4-2.9%; 67 per 100 person-years, 95% CI 45-97) and the median time to develop venous thromboembolism was 25 days (interquartile range 8-148). Reactive thrombocytosis was associated with an increased risk of subsequent venous thromboembolism (hazard ratio 5.3, 95% CI 1.7-16.4), after adjusting for other covariates. Platelet counts explained about 34% of the variability in the risk of venous thromboembolism and had a relatively linear relationship with the risk of venous thromboembolism when the platelet counts were > 400 × 10(9)  L(-1) . Venous thromboembolism after intensive care unit discharge was associated with an increased risk of mortality (hazard ratio 2.0, 95% CI 1.1-3.9), after adjusting for reactive thrombocytosis.

CONCLUSIONS

Reactive thrombocytosis during the recovery phase of critical illness was associated with an increased risk of subsequent venous thromboembolism.

In vitro thrombotic tendency of reactive thrombocytosis in critically ill patients: a prospective case-control study

It is uncertain whether reactive thrombocytosis is associated with an increased risk of thrombosis. This prospective case-control study assessed the in vitro thrombotic tendency of patients with reactive thrombocytosis. Forty-eight patients with reactive thrombocytosis, defined by platelet count >500x10(9)/l and 55 similar, randomly selected critically ill patients who did not have reactive thrombocytosis were considered. In vitro thrombotic tendency in both groups of patients was assessed using maximal amplitude (normal range 54 to 72 mm) and alpha angle (normal range 47 to 74°) on the thromboelastograph. The associations between reactive thrombocytosis and C-reactive protein, the coagulation profile and Sequential Organ Failure Assessment score were also evaluated. Patients with reactive thrombocytosis had an associated increased in vitro thrombotic tendency (maximal amplitude 77 vs 69 mm, mean difference 8 mm, 95% confidence interval 4.9 to 10.9, P=0.001), a higher fibrinogen concentration (7.2 vs 5.8 g/l, P=0.003), and a higher incidence of infection requiring antibiotics (50 vs 27%, P=0.025) compared to patients without thrombocytosis. Platelet count had a relatively linear relationship with the maximal amplitude and the alpha angle of the thromboelastograph tracing (Pearson correlation coefficient: 0.53, P=0.001). In the multivariate analysis, only reactive thrombocytosis (odds ratio 5.9, 95% confidence interval 1.3-27.8, P=0.025) and activated partial thromboplastin time (odds ratio 0.93 per second increment, 95% confidence interval 0.87 to 0.99, P=0.016) were significantly associated with a strong in vitro thrombotic tendency. In summary, reactive thrombocytosis was associated with infection requiring antibiotics and evidence of increased in vitro thrombotic tendency in critically ill patients.

Effect of iron therapy on platelet counts in patients with inflammatory bowel disease-associated anemia

Background and Aims

Secondary thrombocytosis is a clinical feature of unknown significance. In inflammatory bowel disease (IBD), thrombocytosis is considered a marker of active disease; however, iron deficiency itself may trigger platelet generation. In this study we tested the effect of iron therapy on platelet counts in patients with IBD-associated anemia.

Methods

Platelet counts were analyzed before and after iron therapy from four prospective clinical trials. Further, changes in hemoglobin, transferrin saturation, ferritin, C-reactive protein, and leukocyte counts, before and after iron therapy were compared. In a subgroup the effect of erythropoietin treatment was tested. The results were confirmed in a large independent cohort (FERGIcor).

Results

A total of 308 patient records were available for the initial analysis. A dose-depended drop in platelet counts (mean 425 G/L to 320 G/L; p<0.001) was found regardless of the type of iron preparation (iron sulphate, iron sucrose, or ferric carboxymaltose). Concomitant erythropoietin therapy as well as parameters of inflammation (leukocyte counts, C-reactive protein) had no effect on the change in platelet counts. This effect of iron therapy on platelets was confirmed in the FERGIcor study cohort (n=448, mean platelet counts before iron therapy: 383 G/L, after: 310 G/L, p<0.001).

Conclusion

Iron therapy normalizes elevated platelet counts in patients with IBD-associated anemia. Thus, iron deficiency is an important pathogenetic mechanism of secondary thrombocytosis in IBD.

Transient thrombocytosis after endovenous laser treatment for primary varicose vein of the lower extremity

We presented a case of a completely occluded great saphenous vein and transient thrombocytosis following endovenous laser treatment (EVLT) for primary varicose veins of the lower extremity. A 54-year-old man with a left saphenous varicose vein underwent EVLT surgery. Twelve-watt laser irradiation was delivered over the length of 33 cm of the saphenous vein. The cumulative exposure was 1042 J. Nine days after treatment, the platelet count increased up to 610 ⋅ 10(3) /mm(3) and returned to normal after 2 months. A complete occlusion of the great saphenous vein commonly occurs after EVLT, but no case of transient thrombocytosis has been reported.

Systemic thromboembolic complications after laparoscopic splenectomy for idiopathic thrombocytopenic purpura in comparison to open surgery in the absence of anticoagulant prophylaxis

BACKGROUND

Idiopathic thrombocytopenic purpura (ITP) in adults has a chronic course and may necessitate splenectomy. The current study was undertaken to study the systemic thromboembolic complications of laparoscopic splenectomy (LS) versus open splenectomy (OS) in patients with ITP at two large referral hospitals.

PATIENTS AND METHODS

We conducted a retrospective analysis of 49 patients who underwent splenectomy (21 LS and 28 OS) for primary/relapsing refractory ITP between June 1995 and November 2004. Clinically and/or radiologically confirmed deep venous thrombosis (DVT) and/or pulmonary embolism (PE) were assessed within 2 weeks before and after splenectomy. None had prophylactic anticoagulants immediately after surgery. Follow up of those who developed complications continued for at least 2 additional years to assess for contributing factors that may have been masked at the time of occurrence.

RESULTS

Two (9.5%) LS group had acute PE within 5 days of LS and their platelet count reached 500A103/I(1/4)L within 4 days and 1000A103/I(1/4)L within 7 days after surgery. Three conversions to OS occurred; none had VTE. DVT occurred in 3 patients (10.7%) in the OS group; none were life threatening. There were no deaths.

CONCLUSION

Life-threatening venous thromboembolic events are serious complications after LS and OS for ITP patients if prophylactic anticoagulants are not administered. Patients at risk are those who both have an exponential rise of the platelet count, although factors other than the platelet count may be contributing in OS. Postsplenectomy, ITP should be considered as a thrombophilic condition and studies of additional measures to prevent such events are warranted.

Differing effect of systemic anti psoriasis therapies on platelet physiology--a case report and review of literature

BACKGROUND

Psoriasis is a common, chronic relapsing inflammatory skin disease. Lately, there is increasing evidence that psoriasis is more than "skin deep". Epidemiological studies showed that severe psoriasis might have also important systemic manifestations such as metabolic deregulations, cardiovascular disease (CVD) and increased mortality. Moreover, recently psoriasis patients were found to have platelet hyperactivity.

CASE PRESENTATION

This is a case report and review of the literature. We present a patient with long standing severe psoriasis vulgaris with marked thrombocytosis. His thrombocytosis did not correlate with disease severity but rather with the different treatments that he was exposed to, subsiding only during treatment with anti Tumor Necrosis Factor (TNF)- agents. A literature review revealed that in rheumatoid arthritis, another systemic inflammatory disease; interleukin (IL)-6 might be implicated in causing thrombocytosis.

CONCLUSION

This unique case report illustrates that different systemic treatments for psoriasis might have implications beyond the care of skin lesions. This insight is especially important in psoriasis patients in view of their deranged hemostatic balance toward a prothrombotic state, which might increase the risk of thrombosis and CVD. Therefore, further studies analyzing the effect of different drugs on platelets physiology are warranted.

Essential thrombocytemia and acute coronary syndrome: clinical profile and association with other thromboembolic events

BACKGROUND

The existence of a relationship between essential thrombocytemia (ET) and acute coronary syndromes (ACS) has been suggested.

METHOD

Data from eleven consecutive patients admitted with ET in the cardiology department were reviewed.

RESULTS

Nine patients (82%) presented with ACS and two with bradycardia. Patients with ACS had a mean age of 67+/-11 years. Risk factors, especially hypertension (6, 66.7%), and smoking (6, 66.7%) were frequent. Average platelet count was 509 778+/-282 126/mm3. Significant coronary lesions were found in five of six patients studied with coronary angiography. During hospitalization, a patient suffered a thrombotic stroke, a massive pulmonary embolism, and partial aortic thrombosis. Another patient had a transient ischemic attack. Discharge treatments were aspirin (78%), clopidogrel (56%), acenocumarol (33%), hydroxyurea (56%) and anagrelide (44%). Three patients (27%) had thromboembolic events during follow-up (median 1.6 years), 2 patients had coronary events and 1 patient had venous thrombosis. There were neither significant haemorrhages nor deaths.

CONCLUSIONS

Patients with ET and ACS have similar profiles to those of traditional ACS with frequent risk factors and significant coronary artery disease. Association with other thrombotic events can be seen during admission and follow-up while haemorrhagic complications seem to be rare.

A case of essential thrombocythemia in an 8-year-old boy

Thrombocytosis in childhood is not rare but essential thrombocythemia is an extremely rare myeloproliferative disorder in childhood. The authors report a case of essential thrombocythemia in an 8-year-old boy who was diagnosed during further evaluation of an incidental finding of thrombocythemia in a school health examination.

Extreme thrombocytosis--an unusual presentation of inflammatory bowel disease

Thrombocytosis or a high platelet count (a count greater than 400 x 10(9)/L) is a common observation especially with the increased ordering of routine complete blood counts. When found, it may create a diagnostic challenge as transient elevations in platelet counts can occur for a number of reasons such as inflammation or infection, and these usually resolve spontaneously; but an elevated platelet count may be the only indication of an underlying serious disease to which no other clinical findings pertain. The report details a case of extreme thrombocytosis which masked an underlying diagnosis of inflammatory bowel disease.

Cleavage fragments of the third complement component (C3) enhance stromal derived factor-1 (SDF-1)-mediated platelet production during reactive postbleeding thrombocytosis

We hypothesized that the third complement component (C3) cleavage fragments (C3a and (des-Arg)C3a) are involved in stress/inflammation-related thrombocytosis, and investigated their potential role in reactive thrombocytosis induced by bleeding. We found that platelet counts are lower in C3-deficient mice in response to excessive bleeding as compared to normal littermates and that C3a and (des-Arg)C3a enhance stromal-derived factor-1 (SDF-1)-dependent megakaryocyte (Megs) migration, adhesion and platelet shedding. At the molecular level, C3a stimulates in Megs MAPKp42/44 phosphorylation, and enhances incorporation of CXCR4 into membrane lipid rafts increasing the responsiveness of Megs to SDF-1. We found that perturbation of lipid raft formation by statins decreases SDF-1/C3a-dependent platelet production in vitro and in an in vivo model statins ameliorated post-bleeding thrombocytosis. Thus, inhibition of lipid raft formation could find potential clinical application as a means of ameliorating some forms of thrombocytosis.

A critical reappraisal of the WHO classification of the chronic myeloproliferative disorders

Following the introduction of the WHO classification of chronic myeloproliferative disorders (MPDs), after approximately 5 years, a critical reappraisal appears to be warranted. Retrospective clinico-pathological evaluations conducted in the meantime, as well as the detection of new biomarkers, may aid in testing the validity of these new criteria. Based on a large series of patients with chronic myeloid leukemia (CML), an analysis of bone marrow (BM) features and risk classifications revealed that the fiber content exerted a most important and independent impact on prognosis. This finding was also supported in a prospective randomized study and therefore myelofibrosis should be included in any staging system in CML related to survival. Moreover, it is important to emphasize the dynamics of the disease process in MPDs, especially in polycythemia vera (PV) and chronic idiopathic myelofibrosis (CIMF). Latent-stage PV is difficult to recognize when adhering to the proposed limits for hemoglobin (or red cell mass) without regarding the erythropoietin (EPO) level, endogenous erythroid colonies (EECs) or BM histopathology. Initial PV may firstly present with complications and, when accompanied by a high platelet count, mimics essential thrombocythemia (ET). Consequently, BM morphology and EPO level should be entered as major diagnostic criteria for PV. To document more accurately the progress of disease, a simplified scoring system concerning myelofibrosis has to be included in the histological description of CIMF. The diagnostic guidelines of BM features in ET should be improved because, usually, there is neither a significant proliferation nor left-shifting of the granulo- and erythropoiesis detectable and no relevant increase in reticulin. A comparison of clinical data and BM morphology reveals that biomarkers (EPO, EECs, PRV-1, JAK2) show an overlapping pattern of positivity between the different subtypes of MPDs.

Extreme thrombocytosis: what are the etiologies?

Increase platelet count or thrombocytosis, defined as a platelet count greater than or equal to 350 x 10(9)/L, is a common hematologic aberration seen in complete blood cell count. Several etiologies are documented for thrombocytosis. Extreme thrombocytosis, defined as a platelet count greater than or equal to 1,000 x 10(9)/L, is rarely seen in general practice. There are limited data on the etiology of this abnormality. Here, a retrospective investigation for the etiology of severe thrombocytosis was performed. Of the 3 included reports, 535 cases with extreme thrombocytosis were investigated for their etiologies. The 2 defined etiologies are secondary thrombocytosis (66.6%) and clonal thrombocytosis. Of those cases with clonal thrombocytosis, 93.8% had myeloproliferative disorders, and 6.2% had essential thrombocytosis. Concerning bleeding and vaso-occlusive complications, all cases had these complications. In this study, 7.9% of the cases with secondary thrombocytosis experienced bleeding and vaso-occlusive complications, while 17.1% of the cases with clonal thrombocytosis did.

Bone Marrow Histopathology in Myeloproliferative Disorders—Current Diagnostic Approach

Current diagnostic issues in chronic myeloproliferative disorders (MPDs) include the differentiation of essential thrombocythemia (ET) from its mimics: early (prefibrotic) stages of chronic idiopathic myelofibrosis (CIMF) and early polycythemia vera (PV), both of which can be associated with thrombocytosis. Applying a systematic evaluation of bone marrow histopathology, in accordance with the current World Health Organization (WHO) classification system, it is possible to identify cases of true ET as opposed to false ET, usually early-stage CIMF accompanied by an excess of platelets. This distinction is important because the frequency of complications such as progression to overt myelofibrosis, blastic crisis, and overall prognosis are significantly different in the two conditions. The diagnostic criteria of the Polycythemia Vera Study Group (PVSG) do not adequately define the initial stages of PV, nor do they distinguish PV with thrombocytosis from ET. Differentiation of the two is possible by bone marrow histopathology, which also is highly predictive (96%) in distinguishing PV from secondary polycythemia. In conclusion, bone marrow biopsy is an important diagnostic tool for distinguishing specific subtypes of MPD and should be a mandatory step for entry evaluation and follow-up of patients enrolled in prospective studies and/or clinical trials.

Thrombocytosis and toxocariasis: report of two pediatric cases

We report two cases of visceral larva migrans (VLM) syndrome by Toxocara in children. The biological presentation was unusual and characterized by persistent secondary thrombocytosis (>1,000 x 10(9)/L) mimicking an essential thrombocythemia and variable hypereosinophilia syndrome. Both children had non-specific symptoms including abdominal pain, skin rash, and fever. The diagnosis was confirmed by serology. The children were treated with either thiabendazole or albendazole, resulting in normalization of eosinophil and platelet counts.

Progressive stroke due to essential thrombocythemia

We report a case of progressive stroke, due to an intracranial thrombosis, leading to a high-grade stenosis of the internal carotid artery (ICA). Essential thrombocythemia (ET) was identified as the cause of thrombosis. Effective anticoagulation in the acute phase of cerebral ischemia prevented further thrombus organization and total vessel obstruction. After clinical improvement and normalization of platelet counts under hydroxyurea, anticoagulation was stopped and antiplatelet agents were subsequently administered.

Gene expression profiling of normal and malignant CD34-derived megakaryocytic cells

Gene expression profiles of bone marrow (BM) CD34-derived megakaryocytic cells (MKs) were compared in patients with essential thrombocythemia (ET) and healthy subjects using oligonucleotide microarray analysis to identify differentially expressed genes and disease-specific transcripts. We found that proapoptotic genes such as BAX, BNIP3, and BNIP3L were down-regulated in ET MKs together with genes that are components of the mitochondrial permeability transition pore complex, a system with a pivotal role in apoptosis. Conversely, antiapoptotic genes such as IGF1-R and CFLAR were up-regulated in the malignant cells, as was the SDF1 gene, which favors cell survival. On the basis of the array results, we characterized apoptosis of normal and ET MKs by time-course evaluation of annexin-V and sub-G1 peak DNA stainings of immature and mature MKs after culture in serum-free medium with an optimal thrombopoietin concentration, and annexin-V-positive MKs only, with decreasing thrombopoietin concentrations. ET MKs were more resistant to apoptosis than their normal counterparts. We conclude that imbalance between proliferation and apoptosis seems to be an important step in malignant ET megakaryocytopoiesis.

Thromboembolic complications after splenectomy for hematologic diseases

Thromboembolic complications following splenectomy for hematologic diseases occur in up to 10% of patients and may range from portal vein thrombosis (PVT) to pulmonary embolism (PE) and deep vein thrombosis (DVT). Up to now there exist no recommendations for the duration and intensity of prophylactic anticoagulation, which usually follows local institutional protocols. We report on three consecutive patients with severe portal vein thrombosis and/or pulmonary embolism--one with fatal outcome--7 to 35 days after splenectomy for autoimmune hemolytic anemia, immunothrombocytopenia, and indolent lymphoma, respectively. Incidence and pathophysiology of thromboembolic events (TE) in this patient group as well as prophylactic anticoagulation will be discussed, including a review of the current literature on this topic.

Classification and molecular biology of polycythemias (erythrocytoses) and thrombocytosis

In this article, polycythemic disorders are classified based on the current understanding of biology of erythropoieses and divided into primary and secondary polycythemias. Special emphasis is given to recently uncovered molecular bases of newly described congenital polycythemic disorders. This clarification of the pathophysiology of some of the congenital polycythemic states has obvious utility for more accurate diagnosis and rational prognostic determination. The molecular basis of congenital thrombocytoses is only beginning to be uncovered. In contrast, the molecular bases of polycythemia vera and essential thrombocythemia remain unknown, thus their diagnostic criteria are imprecise and their treatment remains largely empirical. The central premise of this article is that deciphering the molecular basis of human diseases leads to improved understanding of hematopoiesis, precise diagnosis, and the potential for development of a specific therapy.