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Haginoya S, Thomovsky EJ, Johnson PA, Brooks AC. Clinical Assessment of Primary Hemostasis: A Review. Top Companion Anim Med 2023; 56-57:100818. [PMID: 37673175 DOI: 10.1016/j.tcam.2023.100818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 08/24/2023] [Accepted: 08/26/2023] [Indexed: 09/08/2023]
Abstract
Primary hemostatic disorders such as thrombocytopenia and thrombocytopathia are commonly encountered in small animal practice. The key stages of primary hemostasis include platelet adhesion, activation, and aggregation. Understanding the interaction between tissues, platelets, and signaling molecules not only helps clinicians comprehend clot formation but also better recognize thrombocytopathias. Although congenital thrombocytopathia is rare, commercially available platelet function tests allow veterinarians to narrow differentials in many clinical settings. Thrombocytopenia can be easily diagnosed in any clinical setting. In this paper, we review the current understanding of primary hemostasis in veterinary medicine, including the clinical presentation and available diagnostics to identify platelet abnormalities.
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Affiliation(s)
- Satoshi Haginoya
- Purdue University College of Veterinary Medicine, West Lafayette, IN, USA.
| | | | - Paula A Johnson
- Purdue University College of Veterinary Medicine, West Lafayette, IN, USA
| | - Aimee C Brooks
- Purdue University College of Veterinary Medicine, West Lafayette, IN, USA
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Belkacemi M, Merad Y. Variables that Influence Platelet Function Analyzer-100™ Closure Times in Healthy Algerian Adults. Int J Appl Basic Med Res 2021; 11:154-159. [PMID: 34458117 PMCID: PMC8360221 DOI: 10.4103/ijabmr.ijabmr_532_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 04/20/2021] [Accepted: 06/02/2021] [Indexed: 11/05/2022] Open
Abstract
Context: The Platelet Function Analyzer (PFA-100™) assesses primary hemostasis in vitro under high shear stress to simulate the conditions to which platelets are exposed at the site of an injured blood vessel wall. Aims: We investigated preanalytical variables in healthy Algerian adults, and we also assess the performance of the test. Subjects and Methods: Closure time (CT) was measured in 302 well-characterized healthy Algerian adults with the collagen/epinephrine (CEPI) and the collagen/adenosine diphosphate (CADP) cartridges. Results: Age and sex did not affect CT values. Blood group O was associated significantly with longer CEPI CT and CADP CT than non-O groups (P ≤ 0.0001 for both). CTs were shorter in samples collected in the morning vs the afternoon (P < 0.0001 for both). We found a strong positive correlation between CT CEPI and CT CADP with r = 0.72 and P < 0.001 and an inverse mean correlation between von Willebrand factor level and CT with r = −0.56, r = −0.45 for CT CEPI and CT CADP, respectively P < 0.001. Duplicate analysis of PFA-100™ CT revealed a mean difference of 3.6% ±19.1% for the CEPI cartridge and 1.5% ±10% for the CADP cartridge. The mean coefficient of variation was 7.4% for the CADP CT and 7.6% for the CEPI CT. No marked difference between test positions. Conclusions: The PFA-100™ showed good reproducibility. The variables influencing the test in healthy Algerian adults are similar to Western and Asian populations. Standardization of preanalytical and analytical conditions is essential for obtaining reliable PFA-100™ results.
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Affiliation(s)
- Malika Belkacemi
- Department of Blood Transfusion, Hassani Abdelkader Hospital, University Center, Sidi-Bel Abbès, Algeria.,Faculty of Medicine, University Djellali Liabes, Sidi-Bel Abbès, Algeria
| | - Yassine Merad
- Faculty of Medicine, University Djellali Liabes, Sidi-Bel Abbès, Algeria.,Department of Parasitology-Mycology, Central Laboratory, Hassani Abdelkader Hospital, University Center, Sidi-Bel Abbès, Algeria
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3
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Vinholt PJ. The role of platelets in bleeding in patients with thrombocytopenia and hematological disease. Clin Chem Lab Med 2020; 57:1808-1817. [PMID: 31465290 DOI: 10.1515/cclm-2019-0380] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/29/2019] [Indexed: 01/19/2023]
Abstract
This review evaluates the role of platelets in bleeding risk among patients with hematological disease and thrombocytopenia. Platelets are pivotal in primary hemostasis, and possess non-hemostatic properties involved in angiogenesis, tissue repair, inflammation and metastatis. Also, platelets safeguard vascular integrity in inflamed vessels. Overall, bleeding risk depends on the underlying disease, and patients with cancer and platelet count <6-10 × 109/L have a markedly increased bleeding risk, while the platelet count does not correlate with bleeding risk at higher platelet counts. Other factors might affect platelet properties and thus bleeding risk, for example, drugs, low hematocrit, coagulation system impairments or transfusion of dysfunctional donor platelets. For patients with leukemia and immune thrombocytopenia, reduced platelet activation, platelet aggregation, or thrombopoiesis, reflected by the reduced presence of reticulated platelets, are associated with bleeding phenotype. However, mechanistic insight into the cause of reduced platelet function in different thrombocytopenic conditions is sparse, except for some inherited platelet disorders. Promising tools for platelet function studies in thrombocytopenia are flow cytometry and biomarker studies on platelet constituents. An important message from this current paper is that bleeding risk assessment must be tailored to specific patient populations and cannot be applied broadly to all patients with thrombocytopenia.
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Affiliation(s)
- Pernille J Vinholt
- Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, J.B. Winsløws vej 4B, 5000 Odense C, Denmark.,University of Southern Denmark, Odense, Denmark
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Lordkipanidzé M, Hvas AM, Harrison P. Clinical Tests of Platelet Function. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00033-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Dovlatova N, Heptinstall S. Platelet aggregation measured by single-platelet counting and using PFA-100 devices. Platelets 2018; 29:656-661. [PMID: 29985716 DOI: 10.1080/09537104.2018.1492109] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Platelets play a crucial role in haemostasis and thrombosis and evaluation of platelet function in vitro, in particular platelet aggregation responses, has been one of the most common and useful ways of evaluating the risk of bleeding and thrombotic events and assessing the effects of various compounds and conditions on platelets. Traditional approaches to assessing platelet aggregation require specialised equipment and trained laboratory personnel and have other limitations. Studying platelet aggregation in whole blood offers a more physiologically relevant measurement. Additionally, certain approaches could be more widely available than in specialised laboratories. Here we summarise the application of the platelet function analyser (PFA-100), an accessible first point-of-care test for platelet function in whole blood, and the less established, but promising approach of assessing platelet aggregation by single-platelet counting that can also be performed in whole blood. The possibilities of a wider and more accessible application of the latter methodology are also discussed.
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Affiliation(s)
- Natalia Dovlatova
- a Thrombosis and Haemostasis Research Group, Division of Clinical Neuroscience , University of Nottingham , Nottingham, United Kingdom.,b Platelet Solutions Ltd ., Nottingham , United Kingdom
| | - Stan Heptinstall
- a Thrombosis and Haemostasis Research Group, Division of Clinical Neuroscience , University of Nottingham , Nottingham, United Kingdom.,b Platelet Solutions Ltd ., Nottingham , United Kingdom
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Skipper MT, Rubak P, Stentoft J, Hvas AM, Larsen OH. Evaluation of platelet function in thrombocytopenia. Platelets 2017; 29:270-276. [PMID: 28409645 DOI: 10.1080/09537104.2017.1296566] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Whole blood aggregometry is a functional assay for determination of platelet function. Until now, whole blood aggregometry has not been considered feasible at low platelet counts. Hence, the objectives of the present study were to explore platelet function in thrombocytopenia using a novel index of impedance aggregometry adjusted for platelet count and evaluate the association to platelet function assessed by flow cytometry. Hirudin anticoagulated blood was collected from 20 healthy volunteers, 20 patients with primary immune thrombocytopenia (ITP), and 17 hematological cancer patients. Platelet function was analyzed by impedance aggregometry and by flow cytometry. Collagen, adenosine diphosphate, thrombin receptor agonist peptide-6, and ristocetin were used as agonists for both analyses. Thrombocytopenia in healthy whole blood was induced in vitro employing a recently published method. Platelet aggregation of thrombocytopenic patients was evaluated relative to the aggregation of healthy volunteers at the same platelet count. In flow cytometry, platelet function was described as expression of the platelet surface glycoproteins: bound fibrinogen, CD63, and P-selectin. Similar platelet counts were obtained in the patient groups (p = 0.69) (range: 13-129 × 109/l). Aggregation adjusted for platelet count was significantly increased in ITP patients compared to healthy platelets across all agonists. The platelet aggregation was high in the 95% prediction interval, with 18 ITP patients above the prediction interval in at least two agonists. In contrast, the platelet aggregation was low in the prediction interval in cancer patients, and three cancer patients with platelet aggregation below the prediction interval in at least one agonist. ITP patients displayed increased expression of bound fibrinogen and CD63 following activation, compared with particularly cancer patients, but also compared with healthy platelets. This study demonstrated the feasibility of a novel approach to perform platelet function analyses in thrombocytopenia using impedance aggregometry adjusted for platelet count.
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Affiliation(s)
- Mette Tiedemann Skipper
- a Centre for Haemophilia and Thrombosis , Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus , Denmark
| | - Peter Rubak
- a Centre for Haemophilia and Thrombosis , Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus , Denmark
| | - Jesper Stentoft
- b Department of Haematology , Aarhus University Hospital, Aarhus University Hospital , Denmark
| | - Anne-Mette Hvas
- a Centre for Haemophilia and Thrombosis , Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus , Denmark
| | - Ole Halfdan Larsen
- a Centre for Haemophilia and Thrombosis , Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus , Denmark
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Forest DJ, Segal S. Update on Thrombocytopenia in Pregnancy and Neuraxial Anesthesia. CURRENT ANESTHESIOLOGY REPORTS 2017. [DOI: 10.1007/s40140-017-0204-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Kuiper GJAJM, Houben R, Wetzels RJH, Verhezen PWM, Oerle RV, Ten Cate H, Henskens YMC, Lancé MD. The use of regression analysis in determining reference intervals for low hematocrit and thrombocyte count in multiple electrode aggregometry and platelet function analyzer 100 testing of platelet function. Platelets 2017; 28:668-675. [PMID: 28067094 DOI: 10.1080/09537104.2016.1257782] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Low platelet counts and hematocrit levels hinder whole blood point-of-care testing of platelet function. Thus far, no reference ranges for MEA (multiple electrode aggregometry) and PFA-100 (platelet function analyzer 100) devices exist for low ranges. Through dilution methods of volunteer whole blood, platelet function at low ranges of platelet count and hematocrit levels was assessed on MEA for four agonists and for PFA-100 in two cartridges. Using (multiple) regression analysis, 95% reference intervals were computed for these low ranges. Low platelet counts affected MEA in a positive correlation (all agonists showed r2 ≥ 0.75) and PFA-100 in an inverse correlation (closure times were prolonged with lower platelet counts). Lowered hematocrit did not affect MEA testing, except for arachidonic acid activation (ASPI), which showed a weak positive correlation (r2 = 0.14). Closure time on PFA-100 testing was inversely correlated with hematocrit for both cartridges. Regression analysis revealed different 95% reference intervals in comparison with originally established intervals for both MEA and PFA-100 in low platelet or hematocrit conditions. Multiple regression analysis of ASPI and both tests on the PFA-100 for combined low platelet and hematocrit conditions revealed that only PFA-100 testing should be adjusted for both thrombocytopenia and anemia. 95% reference intervals were calculated using multiple regression analysis. However, coefficients of determination of PFA-100 were poor, and some variance remained unexplained. Thus, in this pilot study using (multiple) regression analysis, we could establish reference intervals of platelet function in anemia and thrombocytopenia conditions on PFA-100 and in thrombocytopenia conditions on MEA.
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Affiliation(s)
- Gerhardus J A J M Kuiper
- a Department of Anaesthesiology and Pain Treatment , Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands.,b Laboratory for Clinical Thrombosis and Haemostasis, Department of Internal Medicine , Cardiovascular Research Institute Maastricht, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
| | - Rik Houben
- b Laboratory for Clinical Thrombosis and Haemostasis, Department of Internal Medicine , Cardiovascular Research Institute Maastricht, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands.,c Department of Neurology , Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
| | - Rick J H Wetzels
- d Central Diagnostic Laboratory, Cluster for Hemostasis and transfusion, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
| | - Paul W M Verhezen
- d Central Diagnostic Laboratory, Cluster for Hemostasis and transfusion, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
| | - Rene van Oerle
- b Laboratory for Clinical Thrombosis and Haemostasis, Department of Internal Medicine , Cardiovascular Research Institute Maastricht, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands.,d Central Diagnostic Laboratory, Cluster for Hemostasis and transfusion, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
| | - Hugo Ten Cate
- b Laboratory for Clinical Thrombosis and Haemostasis, Department of Internal Medicine , Cardiovascular Research Institute Maastricht, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
| | - Yvonne M C Henskens
- d Central Diagnostic Laboratory, Cluster for Hemostasis and transfusion, Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
| | - Marcus D Lancé
- a Department of Anaesthesiology and Pain Treatment , Maastricht University Medical Center (MUMC+) , Maastricht , The Netherlands
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Bercovitz RS, Brenner MK, Newman DK. A whole blood model of thrombocytopenia that controls platelet count and hematocrit. Ann Hematol 2016; 95:1887-94. [PMID: 27515424 DOI: 10.1007/s00277-016-2777-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 08/01/2016] [Indexed: 01/19/2023]
Abstract
In patients with thrombocytopenia, it can be difficult to predict a patient's bleeding risk based on platelet count alone. Platelet reactivity may provide additional information; however, current clinical assays cannot reliably assess platelet function in the setting of thrombocytopenia. New methods to study platelet reactivity in thrombocytopenic samples are needed. In this study, we sought to develop a laboratory model of thrombocytopenia using blood from healthy subjects that preserves the whole blood environment and reproducibly produces samples with a specific platelet count and hematocrit. We compared the activation state of unstimulated and agonist-stimulated platelets in thrombocytopenic samples derived from this method with normocytic controls. Whole blood was diluted with autologous red blood cell concentrate and platelet-poor plasma, which were obtained via centrifugation, in specific ratios to attain a final sample with a predetermined platelet count and hematocrit. P-selectin exposure and GPIIbIIIa activation in unstimulated platelets and platelets stimulated with collagen-related peptide (CRP) or adenosine diphosphate (ADP) in thrombocytopenic samples and the normocytic control from which they were derived were quantified by flow cytometry. Our methodology reliably produced thrombocytopenic samples with a platelet count ≤50,000/μL and an accurately and precisely controlled hematocrit. P-selectin exposure and GPIIbIIIa activation on unstimulated platelets or on ADP- or CRP-stimulated platelets did not differ in thrombocytopenic samples compared to normocytic controls. We describe a new method for creating thrombocytopenic blood that can be used to better understand the contributions of platelet number and function to hemostasis.
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Affiliation(s)
- R S Bercovitz
- Medical Sciences Institute, PO Box 2178, Milwaukee, WI, 53201, USA.
| | - M K Brenner
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, USA
| | - D K Newman
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI, USA
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Estcourt LJ, Stanworth SJ, Harrison P, Powter G, McClure M, Murphy MF, Mumford AD. Prospective observational cohort study of the association between thromboelastometry, coagulation and platelet parameters and bleeding in patients with haematological malignancies- The ATHENA study. Br J Haematol 2014; 166:581-91. [DOI: 10.1111/bjh.12928] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 03/24/2014] [Indexed: 11/25/2022]
Affiliation(s)
- Lise J. Estcourt
- NHS Blood and Transplant; Oxford UK
- Radcliffe Department of Medicine; University of Oxford; Oxford UK
| | - Simon J. Stanworth
- NHS Blood and Transplant; Oxford UK
- Radcliffe Department of Medicine; University of Oxford; Oxford UK
| | - Paul Harrison
- School of Immunity and Infection; College of Medical and Dental Sciences; University of Birmingham; Birmingham UK
| | | | - Marianne McClure
- Haematology Department; University of Oxford Hospitals NHS Trust; Oxford UK
| | - Michael F. Murphy
- NHS Blood and Transplant; Oxford UK
- Radcliffe Department of Medicine; University of Oxford; Oxford UK
| | - Andrew D. Mumford
- School of Cellular and Molecular Medicine; University of Bristol; Bristol UK
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12
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Vinholt PJ, Hvas AM, Nybo M. An overview of platelet indices and methods for evaluating platelet function in thrombocytopenic patients. Eur J Haematol 2014; 92:367-76. [PMID: 24400878 DOI: 10.1111/ejh.12262] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2013] [Indexed: 12/17/2022]
Abstract
Thrombocytopenia is associated with bleeding risk. However, in thrombocytopenic patients, platelet count does not correlate with bleeding risk and other factors are thus likely to contribute to this risk. This review presents currently available platelet-related markers available on automated haematology analysers and commonly used methods for testing platelet function. The test principles, advantages and disadvantages of each test are described. We also evaluate the current literature regarding the clinical utility of the test for prediction of bleeding in thrombocytopenia in haematological and oncological diseases. We find that several platelet-related markers are available, but information about the clinical utility in thrombocytopenia is limited. Studies support that mean platelet volume (MPV) can aid diagnosing the cause of thrombocytopenia and low MPV may be associated with bleeding in thrombocytopenia. Flow cytometry, platelet aggregometry and platelet secretion tests are used to diagnose specific platelet function defects. The flow cytometric activation marker P-selectin and surface coverage by the Cone-and-Plate[let] analyser predict bleeding in selected thrombocytopenic populations. To fully uncover the clinical utility of platelet-related tests, information about the prevalence of platelet function defects in thrombocytopenic conditions is required. Finally, knowledge of the performance in thrombocytopenic samples from patients is essential.
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Affiliation(s)
- Pernille J Vinholt
- Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark
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Abstract
Platelet function tests have been traditionally used to aid in the diagnosis and management of patients with bleeding problems. Given the role of platelets in atherothrombosis, several dedicated platelet function instruments are now available that are simple to use and can be used as point-of-care assays. These can provide rapid assessment of platelet function within whole blood without the requirement of sample processing. Some tests can be used to monitor antiplatelet therapy and assess risk of bleeding and thrombosis, although current guidelines advise against this. This article discusses the potential utility of tests/instruments that are available.
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Affiliation(s)
- Paul Harrison
- School of Immunity and Infection, University of Birmingham Medical School, Birmingham, UK.
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Flores A, Buchanan GR. Bleeding severity as an important outcome in childhood immune thrombocytopenia. Pediatr Blood Cancer 2013; 60 Suppl 1:S8-11. [PMID: 23109508 DOI: 10.1002/pbc.24344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 08/30/2012] [Indexed: 01/19/2023]
Abstract
Over the years pediatric hematologists have continued to debate whether pharmacotherapy or clinical observation should be employed as initial management in childhood immune thrombocytopenia (ITP). Delineating the fundamental elements of heterogeneity in bleeding manifestations in childhood ITP has proven to be a complicated task. Efforts to classify the impact of hemorrhage in ITP based on platelet count have been problematic. Factors beyond relying on a laboratory measurement as a surrogate marker of disease severity need to be considered. What is needed to better guide therapeutic decision-making is a clinically relevant and evidence-based measure of bleeding severity. In this special supplement, the history of therapeutic management in ITP and prior attempts to grade or quantify hemorrhage will be reviewed.
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Affiliation(s)
- Adolfo Flores
- Division of Hematology-Oncology, Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Center for Cancer and Blood Disorders, Children's Medical Center, Dallas, Texas, USA
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Karger R, Donner-Banzhoff N, Müller HH, Kretschmer V, Hunink M. Diagnostic performance of the platelet function analyzer (PFA-100®) for the detection of disorders of primary haemostasis in patients with a bleeding history–a systematic review and meta-analysis. Platelets 2009; 18:249-60. [PMID: 17538845 DOI: 10.1080/09537100601100366] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The Platelet Function Analyzer (PFA-100) is increasingly being used in the workup of patients with a bleeding diathesis. A profound knowledge of the possible diagnostic performance of this test is essential in order to make sound clinical decisions based on its results. It was the aim of this study to systematically review the published literature and provide valid estimates of the diagnostic performance of the PFA-100 for detecting disorders of primary haemostasis in newly presenting patients with a bleeding diathesis. A comprehensive literature search was performed for studies published between January 1994 and February 2006. Studies were eligible for the systematic review if they provided data supposed to be applicable to the determination of the diagnostic performance of the PFA-100. Furthermore, they were included in a meta-analysis if study reporting allowed calculation of sensitivity and specificity and if study quality ensured minimized biases of these estimates for the described clinical setting. Pooled weighted sensitivity, specificity and diagnostic odds ratio were calculated applying random effects modelling and constructing summary operator characteristic curves. This was done separately for the available test modifications using either collagen/epinephrine (PFA-EPI) or collagen/adenosine-diphosphate (PFA-ADP) for platelet activation. Thirty-six articles were included in the systematic review. Six studies met our eligibility criteria for a meta-analysis. The major reason for exclusion from the meta-analysis was a case-control design. A total of 1486 and 1259 patients were included in the meta-analysis of the diagnostic performance of the PFA-EPI and PFA-ADP, respectively. Pooled weighted sensitivity and specificity of the PFA-EPI/PFA-ADP in detecting a disorder of primary haemostasis were: 82.5/66.9% (95%-confidence interval (95%-CI): 76.0-88.9%/57.9-75.9%), and 88.7/85.5% (95%-CI: 84.3-93.1%/82.0-89.1%). 83/75% of patients with a positive PFA-EPI/PFA-ADP result do have a disorder of primary haemostasis whereas 88/79% with a negative PFA-EPI/PFA-ADP result do not. The PFA-EPI appeared to have a higher sensitivity and better predictive values than the PFA-ADP in detecting disorders of primary haemostasis, although a rigorous gold standard definition for a disorder of primary haemostasis, particularly for platelet disorders, was not applied in most studies. The majority of the studies lacked important requirements for quality and reporting, precluding a more precise and definitive characterization of the clinical utility of the PFA-100. This emphasizes the need for an evidence-based critical appraisal of diagnostic studies in haemostasis research in order to promote the conducting of studies that produce clinically relevant results.
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Affiliation(s)
- Ralf Karger
- Institute for Transfusion Medicine and Haemostaseology, Philipps University, Marburg, Germany.
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Wierenga JR, Jandrey KE, Haskins SC, Tablin F. In vitro comparison of the effects of two forms of hydroxyethyl starch solutions on platelet function in dogs. Am J Vet Res 2007; 68:605-9. [PMID: 17542692 DOI: 10.2460/ajvr.68.6.605] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the effect of 2 hydroxyethyl starch (HES) preparations (ie, HES solution with a molecular weight of 600 kd and a degree of substitution of 0.7 [HES 600/0.7] and a calcium-containing polyionic HES solution with a molecular weight of 670 kd and a degree of substitution of 0.75 [HES 670/0.75]) on canine platelet function. SAMPLE POPULATION Blood samples from 10 healthy adult dogs. PROCEDURES Dilution of citrated whole blood was performed with saline (0.9% NaCl) solution, HES 600/0.7, and HES 670/0.75 at ratios of 1:9 (ie, 1 part saline solution or colloid to 9 parts whole blood) and 1:3. Measurements of time to platelet plug formation in a capillary tube (ie, closure time) were made by use of a bench-top platelet function analyzer with collagen and ADP platelet agonists. RESULTS Mean baseline closure time was 68.0 +/- 15.3 seconds. A 1:3 dilution of whole blood with saline solution, HES 600/0.7, and HES 670/0.75 resulted in mean closure times of 85.8 +/- 15.7 seconds, 100.6 +/- 18.6 seconds, and 101.6 +/- 16.2 seconds, respectively. Closure time following 1:3 dilution of whole blood with saline solution was significantly different from baseline and from 1:9 dilution with saline solution. Closure time following 1:3 dilution of whole blood with HES 670/0.75 was significantly different from baseline, 1:3 and 1:9 dilutions with saline solution, and 1:9 dilutions with HES 600/0.7 or HES 670/0.75. CONCLUSIONS AND CLINICAL RELEVANCE Saline solution, HES 600/0.7, and HES 670/0.75 affect canine platelet function by prolonging closure times; HES solutions prolonged closure time to a greater extent than saline solution.
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Affiliation(s)
- Janelle R Wierenga
- Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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The Platelet Function Analyzer (PFA)-100. Platelets 2007. [DOI: 10.1016/b978-012369367-9/50790-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Wong S, Ward CM, Appleberg M, Lewis DR. POINT OF CARE TESTING OF ASPIRIN RESISTANCE IN PATIENTS WITH VASCULAR DISEASE. ANZ J Surg 2006; 76:873-7. [PMID: 17007614 DOI: 10.1111/j.1445-2197.2006.03693.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The reported range in rates of aspirin resistance (5.5-60%) may reflect difficulties in studying platelet function and the variety of tests used. This study used a platelet function analyzer (PFA-100) to prospectively document aspirin resistance in a cohort of patients with arterial disease. METHODS Patients with internal carotid artery (ICA) stenosis or intermittent claudication (IC) were recruited. Exclusion criteria were contraindications to aspirin, prescription of other medication with known antiplatelet effects or known platelet abnormalities. After prescription of 100 mg aspirin/day for 2 weeks an uncuffed venous blood sample was taken and analysed with the PFA-100. Aspirin resistance was defined as closure time (CT) less than the upper limit of normal (158 s collagen/epinephrine agonist; 118 s collagen/adenosine diphosphate (ADP) agonist). RESULTS Thirty-three patients with IC and 12 patients with ICA stenosis were recruited (n = 45). Median (range) age was 74 years (49-85) and the male to female ratio was 1.5:1. The median (range) CT was >300 (85 to >300) s with collagen/epinephrine and 100 (52 to >300) s with collagen/ADP agonist. Twelve patients (27%) in the collagen/epinephrine group had normal CT despite treatment with 100 mg aspirin, indicating resistance. Of the 33 patients with collagen/epinephrine CT prolonged by aspirin, 10 patients also had prolonged collagen/ADP CT, suggesting excessive platelet inhibition. CONCLUSION A significant proportion of patients taking aspirin do not show laboratory evidence of platelet inhibition and may not be protected from atherothrombotic events. The PFA-100 appears to be a useful tool to screen for both aspirin resistance and excessive aspirin mediated platelet inhibition.
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Affiliation(s)
- Shen Wong
- Department of Vascular Surgery, University of Sydney, The Royal North Shore Hospital, St Leonards, NSW, Australia.
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Hayward CPM, Harrison P, Cattaneo M, Ortel TL, Rao AK. Platelet function analyzer (PFA)-100 closure time in the evaluation of platelet disorders and platelet function. J Thromb Haemost 2006; 4:312-9. [PMID: 16420557 DOI: 10.1111/j.1538-7836.2006.01771.x] [Citation(s) in RCA: 249] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Closure time (CT), measured by platelet function analyzer (PFA-100) device, is now available to the clinical laboratory as a possible alternative or supplement to the bleeding time test. AIM On behalf of the Platelet Physiology Subcommittee of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis (ISTH-SSC), a working Group was formed to review and make recommendations on the use of the PFA-100 CT in the evaluation of platelet function within the clinical laboratory. METHODS The Medline database was searched to review the published information on the PFA-100 CT in the evaluation of platelet disorders and platelet function. This information, and expert opinion, was used to prepare a report and generate consensus recommendations. RESULTS Although the PFA-100 CT is abnormal in some forms of platelet disorders, the test does not have sufficient sensitivity or specificity to be used as a screening tool for platelet disorders. A role of the PFA-100 CT in therapeutic monitoring of platelet function remains to be established. CONCLUSIONS The PFA-100 closure time should be considered optional in the evaluation of platelet disorders and function, and its use in therapeutic monitoring of platelet function is currently best restricted to research studies and prospective clinical trials.
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Affiliation(s)
- C P M Hayward
- McMaster University and the Hamilton Regional Laboratory Medicine Program, Hamilton, ON, Canada.
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Harrison P. The role of PFA-100R testing in the investigation and management of haemostatic defects in children and adults. Br J Haematol 2005; 130:3-10. [PMID: 15982339 DOI: 10.1111/j.1365-2141.2005.05511.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The PFA-100 provides a simple global measure of high shear-dependent platelet function, and as such is not diagnostic or specific to any disorder. Prolonged closure times must be interpreted in conjunction with a full blood count, von Willebrand factor (VWF) screen and other platelet tests. The PFA-100 may also give false negative results with relatively common platelet defects. If clinical suspicion is high, further detailed platelet function testing and VWF screening are required to exclude abnormal platelet function, even if the PFA-100 is normal. In more recent studies the PFA-100 has been used for preoperative identification and management of surgical patients with haemostatic defects and for assessing the clinical effectiveness of platelet transfusion therapy. This review highlights the up to date, evidence-based, advantages and disadvantages of the PFA-100 test in the investigation and management of haemostatic disorders in both children and adults.
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Affiliation(s)
- Paul Harrison
- Oxford Haemophilia Centre and Thrombosis Unit, Churchill Hospital, Headington, Oxford, UK.
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Abstract
Platelet dysfunction likely contributes to the pathophysiology of catastrophic hemorrhages in preterm neonates. In vitro studies have demonstrated that platelets of both term and preterm neonates are hyporesponsive to a variety of agonists. In contrast,template bleeding times of term neonates are shorter than those from adults. Very little is known about this and other tests of primary hemostasis in premature and sick neonates in the neonatal intensive care unit (NICU). This article covers the current knowledge of platelet function in preterm and term neonates and review show new agents (such as recombinant thrombopoietin and recombinant factor VIIa) may enhance neonatal platelet function.
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Affiliation(s)
- Matthew A Saxonhouse
- Division of Neonatology, Department of Pediatrics, University of Florida, College of Medicine, P.O. Box 100296, 1600 SW Archer Road, Gainesville, FL 32610, USA.
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Porto I, Leone AM, Sciahbasi A, Andreotti F. Increased platelet reactivity due to platelet receptor polymorphisms? Not in the real world. Arterioscler Thromb Vasc Biol 2003; 23:1703-4; author reply 1703-4. [PMID: 12972462 DOI: 10.1161/01.atv.0000089502.90231.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
The roles of platelets in hemostasis and arterial thrombosis involve their adherence to sites of vessel injury or ruptured atherosclerotic plaques, aggregation to form hemostatic plugs or thrombi, and acceleration of the coagulation cascade leading to the formation of thrombin. These roles of platelets are described in this review, hereditary platelet defects and other abnormalities associated with bleeding disorders are listed, and the various aggregating agents are discussed. A number of tests of platelet function are reviewed, including a description of their advantages and disadvantages: bleeding time determination; measurement of platelet aggregation in citrated platelet-rich plasma by recording changes in light transmission; measurement of platelet aggregation in citrated whole blood by impedance aggregometry; measurement of platelet-related hemostasis with the high shear Platelet Function Analyzer (PFA-100) system and the Ultegra Rapid Platelet Function Assay; use of the Cone and Plate(let) Analyzer to measure platelet adherence and aggregation under conditions of high shear; measurement of secretion of granule contents (ATP, 14C-serotonin, platelet factor 4, beta-thromboglobulin) and the formation of thromboxane B(2); and use of flow cytometry to assess the state of platelet activation (including conformational changes in membrane glycoproteins and surface expression of P-selectin and phosphatidylserine) ex vivo and in vitro following addition of agonists, and to measure levels of platelet membrane glycoproteins in the detection of inherited deficiencies.
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Affiliation(s)
- Margaret L Rand
- Division of Haematology/Oncology, The Hospital for Sick Children, 555 University Ave., Toronto, Ont., Canada M5G 1X8.
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Grau AJ, Reiners S, Lichy C, Buggle F, Ruf A. Platelet function under aspirin, clopidogrel, and both after ischemic stroke: a case-crossover study. Stroke 2003; 34:849-54. [PMID: 12637702 DOI: 10.1161/01.str.0000064326.65899.ac] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Combined antiplatelet agents may offer additive protection over single drugs after stroke. We investigated whether platelet activation is reduced under combined aspirin and clopidogrel compared with each drug alone. METHODS In a case-crossover study, 31 patients with previous atherothrombotic or lacunar stroke who were treated with aspirin (100 to 300 mg/d) received clopidogrel (75 mg/d) and both aspirin and clopidogrel for 4 weeks. Platelet function in whole blood was studied after each treatment period and in healthy control subjects to assess activation-dependent antigens CD62p and CD63 by flow cytometry and collagen/epinephrine (CEPI-CT) and collagen/ADP (CADP-CT) closure times with the platelet function analyzer PFA-100, which investigates platelet-related function under shear stress. RESULTS CD62p expression and CD63 expression were not different under the 3 treatment regimens. CD63 but not CD62p expression was lower in control subjects than in stroke patients regardless of the antiplatelet treatment (P<0.05). CEPI-CT was prolonged under aspirin and aspirin plus clopidogrel compared with clopidogrel monotherapy (P<0.0001). CADP-CT was longer under combination therapy than under aspirin (P=0.0009) or clopidogrel (P=0.0074) or in control subjects (P=0.0010), mainly because of strong prolongation in a patient subgroup (28%). CONCLUSIONS CD63 expression reflecting the release of platelet lysosomes is consistently increased after stroke and incompletely suppressed by treatment with aspirin, clopidogrel, or both. The strong prolongation of CADP-CT under combined aspirin and clopidogrel in a patient subgroup may indicate a lower risk of thrombosis but also a higher risk of hemorrhage. The predictive value of platelet activation parameters requires investigation in prospective studies.
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Affiliation(s)
- Armin J Grau
- Neurology Department, University of Heidelberg, Germany.
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