Performance and reference intervals of thrombin generation test: results from the Brazilian longitudinal study of adult health (ELSA-Brasil). A cross-sectional study

ABSTRACT BACKGROUND: The thrombin generation test (TGT) has shown promise for investigation of hemorrhagic and thrombotic diseases. However, despite its potential, it still needs standardization. Moreover, few studies have established reference values for TGT parameters. In Brazil, these values have not yet been established. OBJECTIVE: To determine TGT performance and reference intervals for TGT parameters in healthy individuals. DESIGN AND SETTING: Cross-sectional study conducted among participants in the Brazilian Longitudinal Study of Adult Health (Estudo Longitudinal de Saúde do Adulto, ELSA-Brasil). METHODS: The reference sample consisted of 620 healthy individuals. The calibrated automated thrombogram (CAT) method, under low and high tissue factor (TF) conditions, was used to assess thrombin generation. Test performance was analyzed using intra and interassay coefficients of variation (CV) and reference intervals were calculated using the nonparametric method proposed by the International Federation of Clinical Chemistry and the Clinical and Laboratory Standards Institute. RESULTS: The intraassay CV ranged from 1.4% to 2.2% and the interassay CV, 6.8% to 14.7%. The reference intervals for TGT parameters under low and high TF conditions were, respectively: lagtime: 3.0-10.3 and 1.4-3.7 min; endogenous thrombin potential (ETP): 1134.6-2517.9 and 1413.6-2658.0 nM.min; normalized ETP: 0.6-1.3 and 0.7-1.4; peak: 103.2-397.7 and 256.4-479.0 nM; normalized peak: 0.3-1.3 and 0.7-1.2; and time-to-peak: 5.6-16.0 and 3.4-6.7 min. These parameters were categorized relative to sex. Conclusion: TGT performance was adequate and the proposed reference intervals were similar to those of other studies. Our findings may be useful for consolidating the TGT, through contributing to its standardization and validation.

Performance and reference intervals of thrombin generation test: results from the Brazilian longitudinal study of adult health (ELSA-Brasil). A cross-sectional study.

BACKGROUND: The thrombin generation test (TGT) has shown promise for investigation of hemorrhagic and thrombotic diseases. However, despite its potential, it still needs standardization. Moreover, few studies have established reference values for TGT parameters. In Brazil, these values have not yet been established. OBJECTIVE: To determine TGT performance and reference intervals for TGT parameters in healthy individuals. DESIGN AND SETTING: Cross-sectional study conducted among participants in the Brazilian Longitudinal Study of Adult Health (Estudo Longitudinal de Saúde do Adulto, ELSA-Brasil). METHODS: The reference sample consisted of 620 healthy individuals. The calibrated automated thrombogram (CAT) method, under low and high tissue factor (TF) conditions, was used to assess thrombin generation. Test performance was analyzed using intra and interassay coefficients of variation (CV) and reference intervals were calculated using the nonparametric method proposed by the International Federation of Clinical Chemistry and the Clinical and Laboratory Standards Institute. RESULTS: The intraassay CV ranged from 1.4% to 2.2% and the interassay CV, 6.8% to 14.7%. The reference intervals for TGT parameters under low and high TF conditions were, respectively: lagtime: 3.0-10.3 and 1.4-3.7 min; endogenous thrombin potential (ETP): 1134.6-2517.9 and 1413.6-2658.0 nM.min; normalized ETP: 0.6-1.3 and 0.7-1.4; peak: 103.2-397.7 and 256.4-479.0 nM; normalized peak: 0.3-1.3 and 0.7-1.2; and time-to-peak: 5.6-16.0 and 3.4-6.7 min. These parameters were categorized relative to sex. CONCLUSION: TGT performance was adequate and the proposed reference intervals were similar to those of other studies. Our findings may be useful for consolidating the TGT, through contributing to its standardization and validation.

Value of immature reticulocyte fraction in anemias and other hematologic conditions: a brief narrative review

Novos parâmetros hematológicos, como a fração de reticulócitos imaturos (IRF), tendem a se tornar ferramentas importantes na prática clínica. O IRF identifica os reticulócitos mais imaturos, que contêm grande quantidade de ácido ribonucleico, sendo um importante parâmetro para avaliar a atividade da medula óssea, em tempo real, para o diagnóstico diferencial das anemias, acompanhamento do seu tratamento, e para o acompanhamento ou recuperação da medula óssea em diversas condições clínicas. No entanto, ainda há um longo caminho a percorrer antes que a IRF possa ser usada na prática clínica. Assim sendo, é urgente estabelecer os valores de referência e padronizar as metodologias utilizadas pelos diferentes analisadores hematológicos e como expressar seus resultados. Esta revisão narrativa fornece uma perspectiva crítica sobre o IRF e seu potencial para o uso clínico, bem como suas limitações.

New hematological parameters, such as immature reticulocyte fraction (IRF), tend to become important tools in clinical practice. IRF identifies the most immature reticulocytes that contain a large amount of ribonucleic acid, being an important parameter to evaluate bone marrow activity in real time for differential diagnosis of anemias, monitoring of its treatment, and for follow-up or bone marrow recovery in various clinical conditions. However, there is still a long way to go before IRF can be used in clinical practice. Thus, it is urgent to establish reference values and to standardize of the methodologies used by different hematological analyzers and how to express the results. This narrative review provides a critical perspective on IRF, its potential of clinical use and limitations.

Avaliação do conteúdo de hemoglobina do reticulócito em pacientes anêmicos sob tratamento dialítico / Evaluation of the reticulocyte hemoglobin content in anemic patients in dialytic treatment

A anemia é uma complicação importante na doença renal crônica (DRC), culminando com o aumento da morbidade e mortalidade, tornando-se fundamental a busca de marcadores hematológicos que permitam seu diagnóstico precoce. Este artigo teve como objetivo revisar na literatura estudos que investigaram a associação entre o conteúdo de hemoglobina contida nos reticulócitos com a anemia em pacientes com DRC em tratamento dialítico e gerar evidências de sua importância na prática clínica. Foi realizada a busca nas bases de dados eletrônicas: Medline e Web of Science. O período de busca definido foi de janeiro de 1997 a dezembro de 2017. O conteúdo de hemoglobina dos reticulócitos avalia a hemoglobina contida nos reticulócitos, sendo que estes, após liberação da medula óssea, permanecem no sangue periférico de um a quatro dias antes de completar sua maturação, conferindo-lhe maior especificidade em refletir a disponibilidade de ferro aos precursores hematopoiéticos, além de fornecer uma avaliação precoce da resposta eritropoética frente ao tratamento de ferro IV. Os artigos selecionados nessa revisão demonstraram que o conteúdo de hemoglobina do reticulócito, além de refletir precocemente a disponibilidade de ferro aos precursores hematopoiéticos, o mesmo não sofre interferência de citocinas inflamatórias, tornando-o um marcador eficaz no monitoramento da cinética do ferro em pacientes em diálise.

Anemia is an important complication in chronic kidney disease (CKD), culminating with the increase in morbidity and mortality, making it fundamental to search for hematological markers that allow its early diagnosis. This review aimed to review in the literature studies that investigated the association between hemoglobin content in reticulocytes and anemia in patients with CKD in dialysis and to generate evidence of its importance in clinical practice. The hemoglobin content of the reticulocytes evaluates the hemoglobin contained in the reticulocytes, which, after release of the bone marrow, remain in the peripheral blood 1 to 4 days before their maturation completes, giving it greater specificity in reflecting the availability of iron to the reticulocytes. Hematopoietic precursors, in addition to providing an early assessment of the erythropoietic response to IV iron treatment. The articles selected in this review have demonstrated that the reticulocyte hemoglobin content in addition to early reflection of the availability of iron to the hematopoietic precursors does not suffer interference from inflammatory cytokines, making it an effective marker in the monitoring of iron kinetics in dialysis patients.

Platelets volume indexes and cardiovascular risk factors.

Obesity, diabetes and hypertension are risk factors for cardiovascular diseases (CVD) because they promote a state of hypercoagulability. It is known that platelets play an important role in the development of atherosclerosis. Recent studies have evaluated platelet volume indexes (PVIs) in individuals with risk factors for CVD to better understand the platelet mechanisms involved in their development. The IVPs indirectly estimate platelet function and are easily obtained from automated hematology analyzers, which provide platelet counts, mean platelet volume (MPV), platelet distribution width (PDW) and the platelet-large cell ratio (P-LCR). The present study aims to review literature studies that investigated the association between PVIs and obesity, diabetes, and arterial hypertension, in order to evaluate its use as a potential subclinical marker of CVD. Studies have shown promising results for MPV, an index that allows for early detection of platelet activation and may be useful in identifying patients before the onset of CVD development so that preventive strategies can be implemented. The PDW, although evaluated by a smaller number of studies, also showed promising results. However, there is still a long way to go in order for the MPV and PDW to be used in clinical practice, since there is still a need for more epidemiological evidence, establishing reference values, and standardizing the way results are presented.

Platelets volume indexes and cardiovascular risk factors

SUMMARY Obesity, diabetes and hypertension are risk factors for cardiovascular diseases (CVD) because they promote a state of hypercoagulability. It is known that platelets play an important role in the development of atherosclerosis. Recent studies have evaluated platelet volume indexes (PVIs) in individuals with risk factors for CVD to better understand the platelet mechanisms involved in their development. The IVPs indirectly estimate platelet function and are easily obtained from automated hematology analyzers, which provide platelet counts, mean platelet volume (MPV), platelet distribution width (PDW) and the platelet-large cell ratio (P-LCR). The present study aims to review literature studies that investigated the association between PVIs and obesity, diabetes, and arterial hypertension, in order to evaluate its use as a potential subclinical marker of CVD. Studies have shown promising results for MPV, an index that allows for early detection of platelet activation and may be useful in identifying patients before the onset of CVD development so that preventive strategies can be implemented. The PDW, although evaluated by a smaller number of studies, also showed promising results. However, there is still a long way to go in order for the MPV and PDW to be used in clinical practice, since there is still a need for more epidemiological evidence, establishing reference values, and standardizing the way results are presented.

RESUMO A obesidade, o diabetes e a hipertensão arterial são fatores de risco para as doenças cardiovasculares (DCV) por promoverem um estado de hipercoagulabilidade. É sabido que as plaquetas desempenham um importante papel no desenvolvimento da aterosclerose. Diante disso, estudos recentes têm avaliado os índices de volumes plaquetários (IVPs) em indivíduos com fatores de risco para DCV, para melhor se entenderem os mecanismos plaquetários envolvidos no seu desenvolvimento. Os IVPs estimam indiretamente a função plaquetária e são facilmente obtidos a partir de analisadores hematológicos automáticos, que fornecem contagens de plaquetas, volume médio de plaquetas (VPM), largura de distribuição de plaquetas (PDW) e a proporção de plaquetas grandes (P-LCR). O presente trabalho tem por objetivo revisar na literatura estudos que investigaram a associação entre os IVPs e obesidade, diabetes e hipertensão arterial, a fim de avaliar o seu uso como potencial marcador subclínico das DCV. Estudos demonstraram resultados promissores quanto ao VPM, um índice que permite uma detecção precoce da ativação de plaquetas e que pode ser útil na identificação de pacientes antes do início do desenvolvimento de DCV, de tal forma que estratégias preventivas possam ser implantadas. O PDW, embora tenha sido avaliado por um número menor de estudos, também demonstrou resultados promissores. Entretanto, ainda existe um longo caminho a se percorrer para que o VPM e o PDW sejam utilizados na prática clínica, pois ainda são necessárias mais evidências epidemiológicas, o estabelecimento de valores de referência e a padronização da forma de expressar os resultados.