Establishment of reference intervals for Platelet Function Analyzer -100 closure time in Algerian adults

Introduction The Platelet Function Analyzer-100 (PFA-100) is a point of care instrument that simulates plug formation under high shear flow. The PFA-100 measures the time required to occlude the aperture in a biochemically active cartridge and is expressed in a term of closure time (CT). In Algeria, the reference values used in clinical laboratories are of Western origin. However, ethnic, genetic, dietary environmental, and diet differences between populations may affect reference intervals. We established the reference intervals of PFA-100 closure times in healthy Algerian adults according to the International Federation of Clinical Chemistry method, and we compared them with those of Western and Asian countries. Material and methods We enrolled 303 healthy blood donors in the study. 218 subjects met inclusion criteria. We analyzed the blood sample on the PFA-100 for CT with both the collagen epinephrine and collagen ADP cartridges. Results The reference intervals of PFA-100 collagen epinephrine CT and PFA-100 collagen ADP CT were 91–207 seconds and 71–144 seconds, respectively. Compared to Western and Asian populations, there were significant differences. The upper limits of CTs were higher for Algerians in this study. Our findings show that many healthy Algerians would be incorrectly identified as having a primary hemostasis abnormality according to the reference intervals of the manufacturer and scientific literature. Conclusion This report provides the first reference intervals for PFA-100 CTs in healthy Algerian adults. These results improve the accuracy of diagnosis and patient care in Algeria.

Utility of the Platelet Function Analyzer in Patients with Suspected Platelet Function Disorders: Diagnostic Accuracy Study

Introduction The platelet function analyzer (PFA) is widely used as a screening tool for bleeding disorders in various settings. The diagnostic performance regarding platelet function disorders (PFDs), which are among the most common inherited bleeding disorders, is however still elusive. We aimed to assess the diagnostic value of PFA for PFD in clinical practice. Methods Comprehensive clinical and laboratory data of all consecutive patients referred to a specialized outpatient between January 2012 and March 2017 with a suspected bleeding disorder were prospectively recorded. The diagnostic work-up was performed according to a prespecified protocol following current guidelines and platelet function was tested using light transmission aggregometry as well as flow cytometry. Results Five hundred and fifty-five patients were included (median age 43.7 years; interquartile range [IQR] 29.3, 61.7; 66.9% female). Possible PFD was diagnosed in 64 patients (11.5%) and confirmed PFD in 54 patients (9.7%). In patients with confirmed PFD, median closure times were 107 seconds (ADP or adenosine diphosphate; IQR 89, 130) and 169 seconds (EPI; IQR 121, 211). In patients without bleeding disorders, PFA closure times were 96 seconds (ADP; IQR 83, 109) and 137 seconds (EPI; IQR 116, 158). The sensitivity was 19.5% in case of PFA ADP (95%CI 12.6, 30.0; specificity 86.4%; 95% CI 82.4, 89.8), and 44.3% in case of PFA EPI (95% CI 34.9, 53.9; specificity 75.6%; 95% CI 70.8, 79.9). Conclusion The diagnostic performance of PFA for PFD was moderate to poor. Our results do not support the utilization of PFA for screening of PFD in clinical practice.

Prevalence of Coagulation Factors Deficiency among Young Adults in Saudi Arabia: A National Survey

Introduction Inherited bleeding disorders vary in prevalence due to genetic disparity and ethnicity. Little is known about the prevalence of coagulation factor deficiency and bleeding disorders in middle-eastern population. Methods Young Saudi adults with at least one positive bleeding symptom reported in semi-structured validated condensed MCMDM-1vWD questionnaire were tested for complete blood count, routine and special coagulation tests, serum ferritin level, and capillary zone electrophoresis. After initial testing, those with prolonged prothrombin time (PT) or activated prothrombin time (APTT) had further testing to evaluate coagulation factors level. Platelet function was tested through platelet function analyzer (PFA)-100, and multiplate aggregometer (MEA) on patients suspected of having platelet disorders. Results Six-hundred-forty patients (male = 347, 54.2%) were included. A possible platelet function defect was diagnosed in three patients with one matching Glanzmann's thrombasthenia trait pattern, and one that of Bernard-Soulier trait pattern. One patient was diagnosed with von Willebrand disease. Deficiencies in coagulation factor levels were revealed as F-VIII in 14 (7.4%), F-IX in 15 (7.6%), F-II in two (3.3%), F-V in 17 (26.1%), FVII in two (3.1%), and F-X in one (1.8%) of study subjects; low vWF activity (<50%) was found in 14 (8%). Abnormal values were found for various laboratory tests with prolongation of platelet function analyzer-epinephrine (PFA-EPI) in 11%, PFA-ADP or arachidonic acid in 15.2%, PT in 35.9%, and APTT in 63.7%. Five-hundred-seventy-six patients (90%) had normal results in the coagulation factor assays and were categorized as patients with bleeding of unknown cause (BUC). A diagnosis of a bleeding disorder was more frequently made in men than in women (38 vs. 26). Iron deficiency anemia was found in 18 (25%) females positively associated with F-IX deficiency (p-value 0.000). Male gender (73.3%, p = 0.007) was independently associated with the diagnosis of coagulation factor deficiency. Conclusion The current study reports a higher prevalence of coagulation factors deficiency in Saudi population than reported in the western population.

Platelet function in cats with hyperthyroidism

Objectives Cats with hyperthyroidism have been reported to develop thromboembolism, with and without echocardiographic abnormalities consistent with hyperthyroidism. The objective of this study was to compare platelet function in cats with hyperthyroidism with euthyroid age-matched cats. We hypothesized that cats with hyperthyroidism have shortened collagen and adenosine diphosphate (C-ADP) closure times as measured with the platelet function analyzer (PFA-100) in comparison with healthy, age-matched controls. Methods Sixteen hyperthyroid and nine euthyroid healthy cats >7 years of age were recruited from the hospital population. Platelet function, measured using the C-ADP closure times by the PFA-100, and platelet count were measured in healthy euthyroid cats and cats with hyperthyroidism. Results Mean ± SD closure times were not significantly different between control (66.3 ± 9.6 s) and hyperthyroid cats (65.9 ± 11.5 s; P = 0.75). The mean ± SD closure times of hyperthyroid cats that either were untreated or received methimazole for ⩽3 weeks (n = 6; mean 68.5 ± 15.4 s) was not different than that of cats treated for >3 weeks (n = 10; mean 64.3 ± 8.9 s; P = 0.57). The mean automated platelet count was higher in the hyperthyroid group than in the control group ( P = 0.023). Conclusions and relevance Platelet function, as measured by closure time under high shear conditions using C-ADP as an agonist, was not affected by hyperthyroidism in this group of cats. Further research is needed to determine if a hypercoagulable state exists in hyperthyroid cats and the potential roles platelets and von Willebrand factor may have.

Pruebas de función plaquetaria por el sistema PFA-200

Las pruebas de función plaquetaria realizadas con el analizador PFA-200 (del inglés, Platelet Function Analyzer) han venido reemplazando el tiempo de sangría, una prueba ya obsoleta, de acuerdo con el College of American Pathologists (CAP) y la American Society for Clinical Pathology (ASCP). Este analizador, mediante un sistema que utiliza cartuchos, posee la capacidad de simular in vitro las condiciones hemodinámicas del paciente para el tamizaje rápido, sencillo y automatizado de la disfunción plaquetaria. Las pruebas son de utilidad para evaluar la función plaquetaria en pacientes con alteraciones como enfermedad de von Willebrand y otras trombocitopatías congénitas o adquiridas, y evalúa la disfunción plaquetaria causada por inhibidores de la agregación plaquetaria, como la aspirina. Además, son de gran utilidad para el tamizaje prequirúrgico y en los embarazos de alto riego. Este sistema ofrece con su más reciente prueba, la INNOVANCE® PFA-200 P2Y, la posibilidad de evaluar la respuesta de pacientes que están siendo tratados con antagonistas del receptor plaquetario P2Y12, como son clopidogrel, prasugrel y ticagrelor, determinando el porcentaje de adhesión y agregación plaquetaria, logrando discriminar entre un paciente antiagregado y un paciente resistente al tratamiento.