Erythrocytosis: Diagnosis and investigation.

An absolute erythrocytosis is present when the red cell mass is greater than 125% of the predicted. This is suspected when the hemoglobin or hematocrit is above the normal range. An erythrocytosis can be classified as primary or secondary and congenital or acquired. The commonest primary acquired disorder is polycythemia vera. The diagnostic criteria for PV have evolved over time and this is the main diagnosis managed in hematology clinics. There are a variety of rare congenital causes both primary and secondary. In particular in young patients and/or those with a family history a congenital cause is suspected. There remains a larger cohort with acquired erythrocytosis mainly with non-hematological pathology. In order to explore for a cause of erythrocytosis, measurement of the erythropoietin level is a first step. A low erythropoietin level indicates a primary cause and a normal or elevated level indicates a secondary etiology. Further investigation is then dictated by initial findings and includes mutational testing with PCR and NGS for those in whom a congenital cause is suspected. Following this possibly bone marrow biopsy, scans, and further investigation as indicated by history and initial findings. Investigation is directed toward the identification of those with a hematological disorder which would be best managed following guidelines in hematology clinics and referral elsewhere in those for whom there are non-hematological reasons for the elevated hemoglobin.

Association of JAK2V617F allele burden and clinical correlates in polycythemia vera: a systematic review and meta-analysis.

Janus kinase 2 (JAK2) V617F mutation is present in most patients with polycythemia vera (PV). One persistently puzzling aspect unresolved is the association between JAK2V617F allele burden (also known as variant allele frequency) and the relevant clinical characteristics. Numerous studies have reported associations between allele burden and both hematologic and clinical features. While there are strong indications linking high allele burden in PV patients with symptoms and clinical characteristics, not all associations are definitive, and disparate and contradictory findings have been reported. Hence, this study aimed to synthesize existing data from the literature to better understand the association between JAK2V617F allele burden and relevant clinical correlates. Out of the 1,851 studies identified, 39 studies provided evidence related to the association between JAK2V617F allele burden and clinical correlates, and 21 studies were included in meta-analyses. Meta-analyses of correlation demonstrated that leucocyte and erythrocyte counts were significantly and positively correlated with JAK2V617F allele burden, whereas platelet count was not. Meta-analyses of standardized mean difference demonstrated that leucocyte and hematocrit were significantly higher in patients with higher JAK2V617F allele burden, whereas platelet count was significantly lower. Meta-analyses of odds ratio demonstrated that patients who had higher JAK2V617F allele burden had a significantly greater odds ratio for developing pruritus, splenomegaly, thrombosis, myelofibrosis, and acute myeloid leukemia. Our study integrates data from approximately 5,462 patients, contributing insights into the association between JAK2V617F allele burden and various hematological parameters, symptomatic manifestations, and complications. However, varied methods of data presentation and statistical analyses prevented the execution of high-quality meta-analyses.

Exploring hematological alterations and genetics linked to SNV rs10974944 in myeloproliferative neoplasms among Amazon patients.

BCR::ABL1-negative myeloproliferative neoplasms are hematopoietic disorders characterized by panmyelosis. JAK2 V617F is a frequent variant in these diseases and often occurs in the 46/1 haplotype. The G allele of rs10974944 has been shown to be associated with this variant, specifically its acquisition, correlations with familial cases, and laboratory alterations. This study evaluated the association between the 46/1 haplotype and JAK2 V617F in patients with myeloproliferative neoplasms in a population from the Brazilian Amazon. Clinical, laboratory and molecular sequencing analyses were considered. Carriers of the G allele of rs10974944 with polycythemia vera showed an increase in mean corpuscular volume and mean corpuscular hemoglobin, while in those with essential thrombocythemia, there was an elevation in red blood cells, hematocrit, and hemoglobin. Associations were observed between rs10974944 and the JAK2 V617F, in which the G allele (OR 3.4; p < 0.0001) and GG genotype (OR 4.9; p = 0.0016) were associated with JAK2 V617F + and an increase in variant allele frequency (GG: OR 15.8; p = < 0.0001; G: OR 6.0; p = 0.0002). These results suggest an association between rs10974944 (G) and a status for JAK2 V617F, JAK2 V617F + _VAF ≥ 50%, and laboratory alterations in the erythroid lineage.

Red Blood Cell Morphodynamics in Patients with Polycythemia Vera and Stroke.

Polycythemia vera (PV) is a Ph-negative myeloproliferative neoplasm (MPN) which is characterized by erythrocytosis and a high incidence of thrombotic complications, including stroke. The study aimed to evaluate red blood cell (RBC) morphodynamic properties in PV patients and their possible association with stroke. We enrolled 48 patients with PV in this cross-sectional study, 13 of which have a history of ischemic stroke. The control group consisted of 90 healthy subjects. RBC deformability and aggregation analysis were performed using a laser-assisted optical rotational red cell analyzer. The following parameters were calculated: aggregation amplitude (Amp), RBC rouleaux formation time constant (Tf), time of formation of three-dimensional aggregates (Ts), aggregation index (AI), rate of complete disaggregation (y-dis), and the maximal elongation of RBC (EImax). Statistical analysis was performed with the R programming language. There were significant differences in RBCs morphodynamics features between patients with PV and the control group. Lower EImax (0.47 (0.44; 0.51) vs. 0.51 (0.47; 0.54), p < 0.001) and γ-dis (100 (100; 140) vs. 140 (106; 188) s-1, p < 0.001) along with higher amplitude (10.1 (8.6; 12.2) vs. 7.7 (6.6; 9.2), p < 0.001) was seen in patients with PV compared with control. A statistically significant difference between PV patients with and without stroke in aggregation amplitude was found (p = 0.03). A logistic regression model for stroke was built based on RBC morphodynamics which performed reasonably well (p = 0.01). RBC alterations may be associated with overt cerebrovascular disease in PV, suggesting a possible link between erythrocyte morphodynamics and increased risk of stroke.

Microrheological disorders in patients with polycythemia vera suffered acute ischemic stroke.

The relevance of the study is determined by the fact that the combination of cerebrovascular disorders and myeloproliferative diseases requires the search for a predictive biomarker to improve outcomes. The aim of this article was to explore the meanings of microrheological disorders in patients with polycythemia vera (PV) who suffered an acute ischemic stroke (AIS). The study was carried out at the Research center of Neurology. We studied microrheological properties in 181 patients (aged 42-75 years). From the AIS developed in 68 (38%) patients with PV; 59 (32%) patients with AIS were without PV; 54 (30%) patients with PV did not suffer AIS. Microrheological disorders, first of all, the red blood cells (RBC) deformability correlated to AIS severity and its features in comorbid patients. The RBC deformability was dependent on the allelic load of the V617F mutation in the JAK2 gene. Additionally, it was found that RBC deformability perform diagnostic value in the acute phase of ischemic stroke as well as get predictive value for thrombotic complications development within 2 years after AIS in such patients. We suppose that in patients with PV an ischemic stroke and thrombosis would directly depend on the success of PV treatment. In turn, RBC deformability is applicable for some predictive models to late thrombosis development.

Revisiting Diagnostic performances of serum erythropoïetin level and JAK2 mutation for polycythemias: analysis of a cohort of 1090 patients with red cell mass measurement.

We assessed the diagnostic performances of erythropoietin and JAK2 mutations in 1,090 patients with suspected polycythemia who were referred for red cell mass (RCM) measurement. In patients with a high haematocrit and/or haemoglobin level, a low erythropoietin level (<=3·3 mUI/ml) and JAK2 mutation showed comparable positive predictive value (PPV) for true polycythemia (RCM>=125%), 92·1% and 90% respectively. A very-low erythropoietin level (<=1·99 mUI/ml) had a PPV of 100% for polycythemia vera (PV) diagnosis. We confirmed the correlations between RCM, erythropoietin and JAK2 variant allelic frequency in PV patients. This study prompts the need to revisit the role of EPO in PV diagnostic criteria.

MPN and thrombosis was hard enough . . . now there's COVID-19 thrombosis too.

Both myeloproliferative neoplasms (MPNs) and coronavirus disease 2019 (COVID-19) are characterized by an intrinsic thrombotic risk. Little is known about the incidence and the outcome of thrombotic events in patients with MPN infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but common mechanisms of coagulation activation, typical of both disorders, suggest that these patients can be at particularly high risk. To define the best thromboprophylaxis and treatment regimens in both MPN and COVID-19, individual- and disease-specific thrombotic risk factors, bleeding risk, and concomitant specific treatments need to be considered. In this case-based review, an individualized approach is presented in a case of SARS-CoV-2 infection occurring in a man with polycythemia vera (PV). A primary anticoagulant thromboprophylaxis strategy and adjustment of his PV treatment were implemented. However, during the hospital stay, he experienced pulmonary embolism and therapeutic anticoagulation had to be set. Then his condition improved, and discharge was planned. Postdischarge decisions had to be made about the type and duration of venous thromboembolism treatment as well as the management of PV-specific drugs. The steps of our decisions and recommendations are presented.

Circulating Protein Disulfide Isomerase Is Associated with Increased Risk of Thrombosis in JAK2-Mutated Myeloproliferative Neoplasms.

PURPOSE: Thromboembolic events (TE) are the most common complications of myeloproliferative neoplasms (MPN). Clinical parameters, including patient age and mutation status, are used to risk-stratify patients with MPN, but a true biomarker of TE risk is lacking. Protein disulfide isomerase (PDI), an endoplasmic reticulum protein vital for protein folding, also possesses essential extracellular functions, including regulation of thrombus formation. Pharmacologic PDI inhibition prevents thrombus formation, but whether pathologic increases in PDI increase TE risk remains unknown. EXPERIMENTAL DESIGN: We evaluated the association of plasma PDI levels and risk of TE in a cohort of patients with MPN with established diagnosis of polycythemia vera (PV) or essential thrombocythemia (ET), compared with healthy controls. Plasma PDI was measured at enrollment and subjects followed prospectively for development of TE. RESULTS: A subset of patients, primarily those with JAK2-mutated MPN, had significantly elevated plasma PDI levels as compared with controls. Plasma PDI was functionally active. There was no association between PDI levels and clinical parameters typically used to risk-stratify patients with MPN. The risk of TE was 8-fold greater in those with PDI levels above 2.5 ng/mL. Circulating endothelial cells from JAK2-mutated MPN patients, but not platelets, demonstrated augmented PDI release, suggesting endothelial activation as a source of increased plasma PDI in MPN. CONCLUSIONS: The observed association between plasma PDI levels and increased risk of TE in patients with JAK2-mutated MPN has both prognostic and therapeutic implications.

Data-driven analysis of the kinetics of the JAK2V617F allele burden and blood cell counts during hydroxyurea treatment of patients with polycythemia vera, essential thrombocythemia, and primary myelofibrosis.

BACKGROUND: Hydroxyurea (HU) treatment of patients with essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) (MPNs) normalizes elevated blood cell counts within weeks in the large majority of patients. Studies on the impact of HU upon the kinetics of the JAK2V617F allele burden, leukocyte, and platelet counts over time are scarce. PURPOSE: Using data-driven analysis as a novel tool to model the kinetics of the JAK2V617F allele burden and blood cell counts over time during treatment with HU. MATERIAL AND METHODS: Using serial measurements of JAK2V617F and correlation analysis of routine hematological values (the Hb-concentration, leukocyte count, platelet count, and lactic dehydrogenase), we present a detailed description and analysis of the kinetics of the JAK2V617F, leukocyte, and platelet counts and lactic dehydrogenase in 27 patients (PV = 18; ET = 7; PMF = 2), who were followed in the Danish randomized trial (DALIAH). To further analyze the JAK2V617F kinetics, we use a machine learning clustering algorithm to group the response patterns. RESULTS: Response patterns were highly heterogeneous, with clustering resulting in 3 groups and 3 outliers. In the large majority of patients, HU treatment was initially associated with a modest decline in the JAK2V617F allele burden in concert with a decline in leukocyte and platelet counts. However, HU did not induce a sustained and continuous decrease in the JAK2V617F allele burden. CONCLUSION: Using data-driven analysis of the JAK2V617F allele burden, leukocyte, and platelet kinetics during treatment with HU, we have shown that HU does not induce a sustained decrease in the JAK2V617F allele burden and neither induces sustained normalization of elevated cell counts in MPN patients. Our results may explain why MPN patients during treatment with HU still have a substantially increased risk of thrombosis.

Nonvitamin K Antagonist Oral Anticoagulant in Patients With Venous Thromboembolism and Polycythemia Vera or Essential Thrombocythemia: A Cohort Study.

ABSTRACT: Thrombosis is the most common adverse event in patients with polycythemia vera (PV) and essential thrombocythemia (ET). Little is known about the use of nonvitamin K antagonist oral anticoagulants (NOACs) in patients with myeloproliferative neoplasms. We sought to evaluate the efficacy and safety of NOAC in a cohort of patients with PV and ET, who experienced venous thromboembolism (VTE). We enrolled 48 consecutive patients with PV (70.8%) and ET [median age 67.0 (interquartile range, 58.5-72.0) years], who experienced VTE. Patients received apixaban (39.6%), rivaroxaban (33.3%), or dabigatran (27.1%). During a median follow-up of 30 (interquartile range, 20.5-41.5) months, recurrent thrombotic events and bleeding were recorded. Four thrombotic events (3.3 per 100 patient-years) were reported. Three deep vein thrombosis episodes (2.5 per 100 patient-years) were experienced by 2 patients with PV, who received apixaban (5 mg bid) and dabigatran (150 mg bid), and 1 patient with ET, who received dabigatran (150 mg bid). One ischemic stroke occurred in a patient with PV on rivaroxaban (20 mg/d). There was 1 major bleeding (0.8 per 100 patient-years) in a patient with ET on dabigatran (150 mg bid) and 3 clinically relevant nonmajor bleeding (2.5 per 100 patient-years): 2 on rivaroxaban (20 mg/d) and 1 on apixaban (5 mg bid). We did not observe significant differences related to the type of NOAC. Three deaths (2.5 per 100 patient-years) unrelated to either VTE or bleeding were recorded. This study shows that NOACs may be effective and safe as secondary prevention of VTE in patients with myeloproliferative neoplasms.

Evaluation of beta-2 microglobulin, erythropoietin and tobacco use in polycythemic cases.

In the 2016 WHO classification, hemoglobin and hematocrit thresholds for diagnosing polycythemia vera (PV) have been lowered, increasing the number of consultations for polycythemia investigations. In PV, beta-2 microglobulin (B2m) levels are reportedly increased, whereas erythropoietin (EPO) levels are usually low. Most secondary polycythemia cases (SP) are caused by tobacco use. We decided to analyze the relevance of these three parameters in all patients seen for polycythemia investigations to help differentiate PV from SP cases. A cohort of 257 patients (123 PV; 134 SP) was identified. The median B2m level was higher for PV patients (3.16 vs 1.98 mg/l, p < 0.0001). Increased B2m levels were observed in 83.7% of PV patients (11.9% in SP). The median EPO level was lower in PV patients (4.4 vs 12.3 UI/l, p < 0.0001). Tobacco was used by 42.8% of SP patients (8% in PV, p < 0.0001). Increased B2m, low EPO and no tobacco exposure was predictive of PV (specificity and positive predictive value = 100%). Normal B2m, normal EPO and tobacco exposure was predictive of SP (positive predictive value = 100%). These simple and inexpensive parameters could be used to rapidly differentiate PV from SP cases, before prescribing time-consuming JAK2 V617F mutation analysis by specialists.

ABCG2 Is Overexpressed on Red Blood Cells in Ph-Negative Myeloproliferative Neoplasms and Potentiates Ruxolitinib-Induced Apoptosis.

Myeloproliferative neoplasms (MPNs) are a group of disorders characterized by clonal expansion of abnormal hematopoietic stem cells leading to hyperproliferation of one or more myeloid lineages. The main complications in MPNs are high risk of thrombosis and progression to myelofibrosis and leukemia. MPN patients with high risk scores are treated by hydroxyurea (HU), interferon-α, or ruxolitinib, a tyrosine kinase inhibitor. Polycythemia vera (PV) is an MPN characterized by overproduction of red blood cells (RBCs). ABCG2 is a member of the ATP-binding cassette superfamily transporters known to play a crucial role in multidrug resistance development. Proteome analysis showed higher ABCG2 levels in PV RBCs compared to RBCs from healthy controls and an additional increase of these levels in PV patients treated with HU, suggesting that ABCG2 might play a role in multidrug resistance in MPNs. In this work, we explored the role of ABCG2 in the transport of ruxolitinib and HU using human cell lines, RBCs, and in vitro differentiated erythroid progenitors. Using stopped-flow analysis, we showed that HU is not a substrate for ABCG2. Using transfected K562 cells expressing three different levels of recombinant ABCG2, MPN RBCs, and cultured erythroblasts, we showed that ABCG2 potentiates ruxolitinib-induced cytotoxicity that was blocked by the ABCG2-specific inhibitor KO143 suggesting ruxolitinib intracellular import by ABCG2. In silico modeling analysis identified possible ruxolitinib-binding site locations within the cavities of ABCG2. Our study opens new perspectives in ruxolitinib efficacy research targeting cell types depending on ABCG2 expression and polymorphisms among patients.

Reflections on the unexpected laboratory finding of hemorheological alterations observed in some haematological disorders.

Hyperviscosity syndrome is a clinical condition characterized by the slowing of blood flow through the vessels and it may be associated with several diseases. The nosographic classification of primary hyperviscosity conditions (Wells classification 1970) divided the primary hyperviscosity syndromes in polycythaemic, sclerocytemic and sieric. Recent and personal laboratory observations have highlighted an unexpected behaviour of the erythrocyte deformability observed in some haematological disorders such as polycythemia vera, multiple myeloma and monoclonal gammopathy of undetermined significance. The interest of this observation depends on the fact that up to now, according to the Wells classification, the hemorheological alteration present in PV was related to the increase of RBC mass while that present in MM and MGUS was attributable to the abnormality of plasma or serum viscosity only. Through an extensive research among the literature, using MEDLINE/PubMed to identify all published reports on the hyperviscosity syndromes, issues that until now have been dealt with separately will therefore be analyzed in a unique paper, allowing a global view. The aim of this paper is to provide some suggestions for reflection and emphasizing the need of a nosographic framework of hyperviscosity that, probably, deserves to be reviewed.

Aberrant expression of cytokines in polycythemia vera correlate with the risk of thrombosis.

BACKGROUND: Thrombo-hemorrhagic complications cause significant morbidity and mortality in patients with polycythemia vera (PV). OBJECTIVES: To assay and correlate inflammatory cytokines with the thrombotic risk in PV patients. METHODS: This prospective observational study was carried out at Postgraduate Institute of Medical Education and Research, Chandigarh, India over 18-months. The study enrolled 52 patients with PV (newly diagnosed = 28, follow-up = 24), and 20 age/sex-matched controls. Cytokine analysis for IL 1ß, IL2, IL4, IL6, IL8, IL10, IL11, IL12/23p40, TNFα, and IFN-γ was performed on the peripheral blood (before treatment initiation for newly diagnosed cases, and after 7 days of stopping drugs for follow-up cases) by flow cytometry-based cytokine bead analysis (CBA) using CBA kits (BD™ biosciences, USA). Results were analyzed using SPSS Statistics 22.0. RESULTS: The mean age of patients was 51.9 ± 13 years. Levels of IL-6, IL-1ß, IL-8, IL-11, IL-12/23p40 were significantly raised, however, TNF-α, and IFN-γ levels were significantly lower in the PV population as compared to controls. A significant correlation between the levels of IL-6, IL-2, and IL-8 with the overall risk of thrombosis in PV patients was observed. CONCLUSIONS: PV patients display an aberrant pattern of plasma cytokine expression, the levels of which correlate with the thrombotic risk.

Automated diagnostic support system with deep learning algorithms for distinction of Philadelphia chromosome-negative myeloproliferative neoplasms using peripheral blood specimen.

Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-negative MPNs) such as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis are characterized by abnormal proliferation of mature bone marrow cell lineages. Since various non-hematologic disorders can also cause leukocytosis, thrombocytosis and polycythemia, the detection of abnormal peripheral blood cells is essential for the diagnostic screening of Ph-negative MPNs. We sought to develop an automated diagnostic support system of Ph-negative MPNs. Our strategy was to combine the complete blood cell count and research parameters obtained by an automated hematology analyzer (Sysmex XN-9000) with morphological parameters that were extracted using a convolutional neural network deep learning system equipped with an Extreme Gradient Boosting (XGBoost)-based decision-making algorithm. The developed system showed promising performance in the differentiation of PV, ET, and MF with high accuracy when compared with those of the human diagnoses, namely: > 90% sensitivity and > 90% specificity. The calculated area under the curve of the ROC curves were 0.990, 0.967, and 0.974 for PV, ET, MF, respectively. This study is a step toward establishing a universal automated diagnostic system for all types of hematology disorders.

Development and validation of a sequential two-step algorithm for the screening of individuals with potential polycythaemia vera.

In 2016, the WHO included haemoglobin values within normal ranges as a diagnostic criterion for Polycythaemia Vera (PV). Since then, concerns have arisen that a large number of patients are undergoing unnecessary screening for PV. To address this issue, we estimated the prevalence of JAK2 p.V617F in individuals with elevated haemoglobin or haematocrit and developed and validated a screening algorithm for PV. A total of 15,366 blood counts performed in seven non-consecutive days were reviewed, of which 1001 were selected for subsequent JAK2 p.V617F mutation screening. Eight (0.8%) new JAK2 p.V617F-mutated cases were detected. From ROC curves, a two-step algorithm was developed based on the optimal cut-off for the detection of the JAK2 p.V617F mutation. The algorithm was prospectively validated in an independent cohort of 15,298 blood counts. A total of 1595 (10.4%) cases met the criterion for haemoglobin or haematocrit, of whom 581 passed to step 2 (3.8% of the total). The JAK2 p.V617F mutation was detected in 7 of the 501 patients tested, which accounts for 0.04% of the total cohort and 0.4% of patients with erythrocytosis. In conclusion, this data show that our two-step algorithm improves the selection of candidates for JAK2 p.V617F testing.

Altered Ca2+ Homeostasis in Red Blood Cells of Polycythemia Vera Patients Following Disturbed Organelle Sorting during Terminal Erythropoiesis.

Over 95% of Polycythemia Vera (PV) patients carry the V617F mutation in the tyrosine kinase Janus kinase 2 (JAK2), resulting in uncontrolled erythroid proliferation and a high risk of thrombosis. Using mass spectrometry, we analyzed the RBC membrane proteome and showed elevated levels of multiple Ca2+ binding proteins as well as endoplasmic-reticulum-residing proteins in PV RBC membranes compared with RBC membranes from healthy individuals. In this study, we investigated the impact of JAK2V617F on (1) calcium homeostasis and RBC ion channel activity and (2) protein expression and sorting during terminal erythroid differentiation. Our data from automated patch-clamp show modified calcium homeostasis in PV RBCs and cell lines expressing JAK2V617F, with a functional impact on the activity of the Gárdos channel that could contribute to cellular dehydration. We show that JAK2V617F could play a role in organelle retention during the enucleation step of erythroid differentiation, resulting in modified whole cell proteome in reticulocytes and RBCs in PV patients. Given the central role that calcium plays in the regulation of signaling pathways, our study opens new perspectives to exploring the relationship between JAK2V617F, calcium homeostasis, and cellular abnormalities in myeloproliferative neoplasms, including cellular interactions in the bloodstream in relation to thrombotic events.