Hemofilia adquirida A en embarazo. Caso clínico de medicina crítica en obstetricia por morbilidad extrema y su abordaje transdisciplinario perioperatorio / Acquired hemophilia A in pregnancy. Clinical case of critical medicine in obstetrics due to extreme morbidity and its perioperative transdisciplinary approach

Resumen: La identificación de múltiples factores de riesgo que predisponen a la hemorragia durante el evento obstétrico, como la hemofilia adquirida que es un trastorno que se desarrolla por la generación de autoanticuerpos inhibidores de factores de la coagulación, la interpretación objetiva de las pruebas de laboratorio rutinarias, el desarrollo de un pensamiento sistematizado en la integración diagnóstico-terapéutica por parte del personal de salud, y la disposición de los recursos farmacológicos hospitalarios, es lo que determina frecuentemente el pronóstico en pacientes obstétricas con morbilidad extrema que requieren atención multidisciplinaria en las diferentes unidades hospitalarias del sector salud de nuestro país. El objetivo es presentar un caso clínico de morbilidad extrema por hemofilia adquirida, su presentación clínica, evolución y desenlace fatal. Se presenta un caso referido de otra unidad del Sector Salud ISEM (Instituto de Salud del Estado de México), atendido en la Unidad de Cuidados Intensivos Obstétricos del Hospital «Mónica Pretelini Sáenz¼, resaltando la importancia en la integración diagnóstico-terapéutica y la interacción multifactorial de variables relacionadas con su desenlace fatal. Conclusiones: Desconocimiento de la patología, retraso en el diagnóstico, múltiples procedimientos condicionantes de hemorragia iatrógena y la limitación en recursos terapéuticos son factores que contribuyen a un desenlace fatal.

Abstract: The identification of multiple risk factors that predispose to bleeding during the obstetric event, such as acquired hemophilia, which is a disorder that develops due to the generation of autoantibodies that inhibit coagulation factors, the objective interpretation of routine laboratory tests , the development of systematized thinking in diagnostic-therapeutic integration by health personnel, and the provision of hospital pharmacological resources, is what frequently determines the prognosis in obstetric patients with extreme morbidity who require multidisciplinary care in the different hospital units of the health sector of our country. The objective is to present a clinical case of extreme morbidity due to acquired hemophilia, its clinical presentation, evolution and fatal outcome. A case referred from another unit of the ISEM (Instituto de Salud del Estado de México) Health Sector, treated at the Obstetric Intensive Care Unit of the «Mónica Pretelini Sáenz¼ Hospital, is presented, highlighting the importance of diagnostic-therapeutic integration, and the multifactorial interaction of variables related to its fatal outcome. Conclusions: Ignorance of the pathology, delay in diagnosis, multiple conditioning procedures of iatrogenic hemorrhage and the limitation in therapeutic resources are factors that contribute to a fatal outcome.

Manifestaciones clínicas de la deficiencia de factor XII en un lactante

RESUMEN Introducción: El factor XII o factor de Hageman pertenece al sistema de contacto al ser iniciador de la vía intrínseca de la coagulación. Concentraciones bajas de este factor se asocian a tiempo de tromboplastina parcial activado prolongado, sin embargo, no se producen manifestaciones hemorrágicas como ocurre en la deficiencia de otros factores. Objetivo: Describir las manifestaciones clínicas de un lactante con diagnóstico de deficiencia de factor XII de la coagulación. Presentación del caso: Se presenta un lactante de 10 meses que tuvo aparición espontánea de equimosis y se diagnosticó un déficit de factor XII. Conclusiones: Aunque no es común, la deficiencia del factor XII puede estar asociada a manifestaciones hemorrágicas como equimosis tal como se describe en el presente caso.

ABSTRACT Introduction: Factor XII or Hageman factor belongs to the contact system as it is the initiator of the intrinsic coagulation pathway. Low concentrations of this factor are associated with prolonged activated partial thromboplastin time, however, hemorrhagic manifestations do not occur as occurs in the deficiency of other factors. Objective: Describe the clinical manifestations of an infant diagnosed with coagulation factor XII deficiency. Case presentation: A 10-month-old infant who had spontaneous onset of ecchymosis and a factor XII deficiency was diagnosed. Conclusions: Although not common, factor XII deficiency may be associated with hemorrhagic manifestations such as ecchymosis, as described in the present case.

Actividad anticoagulante in vitro del extracto etanólico de las hojas de dos especies de la familia Euphorbiaceae / In vitro anticoagulant activity of the ethanolic extract of the leaves of two species of the family Euphorbiaceae

RESUMEN Las enfermedades cardiovasculares (ECV) son un conjunto de trastornos del corazón y de los vasos sanguíneos, que constituyen la principal causa de mortalidad en el mundo. En la búsqueda de alternativas para esta problemática, plantas medicinales de la familia Euphorbiaceae, han sido empeladas con fines terapéuticos, para prevenir, atenuar o curar los efectos generados por estas enfermedades. El objetivo de este trabajo fue conocer el perfil fitoquímico y evaluar la actividad anticoagulante in vitro de los extractos etanólicos de las hojas de Croton malambo y Acalypha hispida sobre plasma humano. Para ello, se obtuvo el extracto de las hojas y se le realizó el tamizaje fitoquímico, la evaluación del Tiempo de Tromboplastina Parcial activada (TTPa) y del Tiempo de Protombina (TP). En el perfil fitoquímico, se confirmó la presencia de alcaloides, taninos, flavonoides, leucoantocianidinas, fenoles, sesquiterpenlactonas, glucósidos cardiotónicos y terpenos. En la actividad anticoagulante, se evidenció la inhibición de la coagulación en la vía intrínseca, obteniendo resultados significativos para el TTPa, a diferencia que el test TP, donde los resultados obtenidos se encontraron similares al control. Esta investigación demuestra la acción anticoagulante de las plantas, ya que induce, significativamente, a una mayor prolongación del tiempo de coagulación; ambas especies presentaron una mayor actividad, a 200 mg/mL.

ABSTRACT Cardiovascular diseases (CVD) are a group of disorders of the heart and blood vessels, which correspond to the principal causes of death in the world. In the search for alternatives to this problem, medicinal plants of the Euphorbiaceae family have been investigated for therapeutic purposes to prevent, attenuate or cure the effects generated for these illnesses. The objective of this work was to know the phytochemical profile and evaluate the anticoagulant activity in vitro of the ethanolic extracts of the leaves of Croton malambo and Acalypha hispida on human plasma. For this, extract of their leaves was obtained, and phytochemical screening was performed, as well as the evaluation of the Activated Partial Thromboplastin Time (aPTT) and the Prothrombin Time (TP). The phytochemical profile confirmed the presence of alkaloids, tannins, flavonoids, leucoanthocyanidins, phenols, sesquiterpene lactones, cardiotonic glycosides, and terpenes. In the anticoagulant activity, the inhibition of coagulation in the intrinsic pathway was evidenced, obtaining significant results for aPTT, unlike the TP test where the results obtained were like the control. This research demonstrates the effectiveness of the plant with anticoagulant action since they significantly induce a longer prolongation of the clotting time, both species showed higher activity at 200 mg/mL.

Secondary hemostasis studies of crude venom and isolated proteins from the snake Crotalus durissus terrificus.

Among the activities triggered by Crotalus durissus terrificus snake venom, coagulation is intriguing and contradictory since the venom contains both coagulant and anticoagulant precursor proteins. This work describes the in vitro effects of crude venom and purified proteins from snake Crotalus durissus terrificus as they affect coagulation factors of clotting pathways. Coagulant and/or anticoagulant activities of crude venom, and purified proteins were all analyzed directly in human plasma. Clots formed by crude venom and Gyroxin presented as flexible hyaline masses in punctiform distribution. Clot formation time evaluation of isolated proteins with PT and APTT assays made it possible to infer that these proteins interfere in all coagulation pathways. However, regarding ophidism by C. d. terrificus, Gyroxin acts directly, breaking down fibrinogen to fibrin and increasing the amount plasminogen activator, which results in the formation of thrombi. Crotoxin complex, Crotoxin A and Crotoxin B proteins can act in prothrombinase complex formation; Crotoxin B can inhibit prothrombinase complex formation by direct interaction with Factor Xa. Crotamine interacts with negatively charged regions of differing coagulation factors in all coagulation pathways, and possesses a whole set of activities causing dysfunction, activation and/or inhibition of natural anticoagulants and disturbing hemostasis.

Hemostatic profile in patients with and without postpartum hemorrhage / Perfil hemostático en pacientes con y sin hemorragia obstétrica posparto

Background: The association between coagulation profile and postpartum hemorrhage (PH) is still debated. Objective: To determine the association between hemostatic profile and PH in women with cesarean operation (CO). Methods: We included 92 patients with PH (cases) and 184 without (controls), patients were attended during 2014, at one hospital of the Instituto Mexicano del Seguro Social in Mérida, Yucatán. Demographic, clinical and laboratory data including prothrombin time (PT), activated partial thromboplastin time (aPTT), platelet count (PLC), and fibrinogen concentration were compared among cases and controls using a binary logistic regression model (LRM), from which odd ratios (OR), and 95% confidence intervals (95% CI), were obtained. Results: According to the bivariate comparison, in the LRM categorical data such as parity, any type of hypertensive comorbidity, type of anesthesia, and categorized aPTT (< 38 vs. ≥ 38 seconds), and one continuous variable (gestational age) were included. Having some hypertensive comorbidity (OR 3.55, 95% CI: 1.95-6.47), type of anesthesia (regional anesthesia, OR 0.27, 95% CI: 0.13-0.55) and aPTT (< 38 seconds, OR 0.26, 95% CI: 0.10-0.66) were all statistically significant. Categorized PT, platelet count and fibrinogen concentration, were not statistically significant. Conclusions: In this sample, having some hypertensive comorbidity increased risk of PH more than three times, while regional anesthesia and aPTT < 38 seconds reduced risk in 73% and 74%, respectively. Neither platelet count, nor fibrinogen concentration, or the PT categories modified risk of PH.

Introducción: la asociación entre el perfil hemostático y la hemorragia obstétrica posparto (HO) es controversial. Objetivo: determinar la asociación entre el perfil hemostático y la HO en pacientes con operación cesárea (OC). Métodos: se incluyeron 92 pacientes con HO (casos) y 184 sin HO (controles), atendidas durante 2014 en un hospital del Instituto Mexicano del Seguro Social de Mérida, Yucatán. Diversas variables, incluyendo la cuenta plaquetaria, el tiempo de protrombina (TP), el tiempo de tromboplastina parcial activado (TTPa) y el fibrinógeno plasmático, fueron comparadas entre casos y controles, mediante un modelo de regresión logística del que se obtuvieron razones de momios (RM) e intervalos de confianza de 95% (IC 95%). Resultados: con base en el análisis univariado se incluyeron en el modelo la paridad, comorbilidad hipertensiva (hipertensión crónica, preeclampsia, eclampsia), tipo de anestesia y el TTPa categorizado (< 38 frente a ≥ 38 segundos) y la edad gestacional (como dato continuo), resultando significativamente diferentes la presencia de comorbilidad hipertensiva (RM 3.55, IC 95%: 1.95-6.47), el tipo de anestesia (regional, RM 0.27, IC 95%: 0.13-0.55) y el TTPa (< 38 segundos, RM 0.26, IC 95%: 0.10-0.66). Conclusiones: en esta muestra, tener comorbilidad hipertensiva incrementó más de tres veces el riesgo de HO, la anestesia regional lo redujo en 73% y el TTPa < 38 segundos lo redujo en 74%. Ni el TP, ni la cuenta plaquetaria modificaron el riesgo.

Routine Coagulation Tests in Patients With Nonvalvular Atrial Fibrillation Under Dabigatran and Rivaroxaban Therapy: An Affordable and Reliable Strategy?

Dabigatran and rivaroxaban, direct oral anticoagulants (DOACs), affect coagulation tests, and knowledge of their effects is important for therapeutic monitoring. Our aim was to examine the association between DOAC levels and routine coagulation tests in patients with nonvalvular atrial fibrillation. Samples from patients receiving dabigatran (150 mg) and patients receiving rivaroxaban (20 mg) were collected 2 hours after drug intake. Direct oral anticoagulant concentrations were determined using direct Hemoclot thrombin inhibitor (HTI) assay (HTI test) and a direct Xa inhibitor (Anti Xa-Riva). The routine coagulation measured included activated partial thromboplastin time (aPTT) and prothrombin time (PT). The median plasmatic dabigatran was 128.3 ng/mL (95% confidence interval [CI]: 93.7-222.6 ng/mL). The HTI exhibited a good correlation with aPTT ( R2 = 0.74; P < .0001). The median plasmatic rivaroxaban was 223.9 ng/mL (95% CI: 212.3-238.9 ng/mL). Anti-Xa-Riva correlated with PT ( R2 = 0.69, P< .0001) and aPTT (R2 = 0.36, P < .001), but prolonged PT results were obtained, even below the rivaroxaban therapeutic range (20%). The routine coagulation tests were able to identify out of therapeutic range concentrations for dabigatran and rivaroxaban. We suggest the use of these screening tests to better understand and monitor the subtherapeutic concentrations of these DOACs.

A 2-year-old boy with circulatory failure owing to streptococcal toxic shock syndrome: case report.

A 2-year-old boy presented with severe hypotension and acute kidney injury after a prodrome of non-bloody diarrhoea and fever in the preceding 3 days. He had a mild Ebstein cardiac anomaly but otherwise a normal past history and growth. On examination, he looked ill, his temperature was 37.5 °C, circulation was poor, and there were several purpuric lesions on the face, hands and scrotum. Haemoglobin was 7.8 g/dL (11-14), total white cell count 27 × 109/L, platelets 62 × 109/L, blood urea nitrogen 20.7 mmol/L (4.2-17.1), serum creatinine 95.4 µmol/L (21.2-36.2), CRP 154 mg/L (<5), AST 296 U/L (11-50), ALT 909 U/L (7-40) and C3 component of complement 0.8 g/L (0.9-1.8). Activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged and fibrinogen level was 1.0 g/L (2-4). He received immediate fluid resuscitation (IV 0.9% saline solution, 2 × 10 ml/kg boluses, followed by glucose 5/0.45% sodium chloride solution, 2 × 10 ml/kg) and antibiotics (ciprofloxacin and amikacin) but circulation continued to deteriorate with development of decreased consciousness. He was placed on mechanical ventilation and vasopressor agents were added. Despite improved circulation over the next 2 days, he developed oliguria, progressive fluid overload, generalised oedema and a right-sided pleural effusion. Dialysis was commenced on day 3 of admission. Differential diagnosis included sepsis, atypical haemolytic uraemic syndrome and lupus nephritis. Blood and urine cultures remained negative but an anti-streptolysin O titre of 1318 (<200) IU/mL led to the diagnosis of streptococcal toxic shock syndrome which is rare in early childhood and associated with high mortality. Haemodialysis was commenced and continued for 10 days with successful treatment of fluid overload and subsequent extubation. Renal function was completely restored over the following 6 weeks and he was discharged in good clinical condition about 2 months after intial admission. The clinical course and outcome are discussed, and the importance of timely initiation of dialysis when there is fluid overload is emphasised.

Variabilidade na sensibilidade à heparina de reagentes do TTPA em plasmas heparinizado in vitro e de pacientes heparinizados / Variability in heparin sensitivity of TTPA reagents in heparinized plasma in vitro and patients receiving heparin

Introdução: No final da década de 80 e início dos anos 90 vários estudos demonstraram a falta de padronização e a variabilidade nos resultados do TTPA devido a diferentes sensibilidades à heparina dos reagentes empregados para sua determinação. Objetivo: Avaliar a sensibilidade à heparina de reagentes utilizados para a determinação do TTPA em amostras de plasmas heparinizadas in vitro e de pacientes em uso de heparina não fracionada (HNF). Material e Métodos: Para este estudo foi utilizado um pool de plasma heparinizado, com concentrações de 0,1 até 1,0 unidade de heparina/mL, 29 pacientes em uso de HNF e 8 kits de reagentes para a determinação do TTPA. Resultados e Discussão: Com os plasmas heparinizados in vitro os resultados com o reagente da Actin® foram estatísticamente diferente dos da Labtest®, da Human® e da Clot®. O melhor coeficiente de correlação, resultado do TTPA versus concentração de HNF, foi observado com o reagente da Stago® (R=0,9919). Quando-se empregou os plasmas de pacientes em uso de HNF os resultados do Actin® e do Actin FSL® foram estatisticamente diferentes dos da Clot®. Conclusão: Diferenças estatisticamente significativas, nos valores de TTPA, ainda são observadas, tanto em plasmas de pacientes em uso de HNF como em plasmas heparinizados in vitro de acordo com o reagente utilizado.

Introduction: At the end of the 1980s and at the beginning of the 1990s, several studies showed lack of standardization and variability in APPT results due to the different sensibilities to heparin in reagents used for its determination. Objective: To evaluate the sensibility to heparin in the different reagents used to determine APPT in samples of heparinized plasma in vitro and in patients using non-fractioned heparin (NFH). Material and Methods: This study was performed with a pool of heparinized plasma with concentrations from 0.1 to 1.0 unit heparin/mL, 29 patients using NFH and 8 reagent kits for TTPA determination. Results and Discussion: Using heparinized plasma in vitro, there was a statistically significant difference with Actin® reagent in relation to Labtest®, Human® and Clot® reagents. The best correlation coefficient, a result of the APTT versus UFH concentration was observed with reagent from Stago® (R = 0.9919). When we used the plasma from patients using UFH, the results of Actin ® and Actin FSL® were statistically different from the Clot®.

Valores de Referência para tempos de coagulação em uma população de cães de Porto Alegre, RS, Brasil / Reference values for coagulation time of dogs in Porto Alegre, RS, Brazil

Background: Prothrombin time (PT) and activated partial thromboplastin time (PTT) are screening tests for coagulopathies in dogs. Both tests measure the clotting ability by the activation of different parts of the coagulation cascade. These tests vary widely in terms of reference parameters, mainly due the considerable diversity of reagents and analyzers available. In addition, there are many variations inherent to different populations, and little has been published about coagulation reference parameters for the local dog population. The main objective of the present study was to determine a clotting time reference range of a dog population in Porto Alegre, Rio Grande do Sul, Brazil.Materials, Methods & Results: Hemostatic reference range was determined from citrated plasma of 268 clinically heathy dogs of both genders. The animals did not present bleeding diathesis or thrombocytopenia history. All dogs were previously submitted to clinical examination (cardiopulmonary auscultation, abdominal palpation, and rectal temperature) and laboratory screening (complete blood count, creatinine, albumin, and alanine aminotransferase). PT and PTT of 71 and 258 samples were measured, respectively. Blood samples were collected into 2.7 mL 3.2 % sodium citrate tubes (9 parts blood : 1 part citrate) by vacuum. Blood samples were centrifuged; the plasma was harvested and stored at -30 °C upon analyses. All analyses were performed using the viscosity detection method in semi-automatic coagulometer according to manufacturers guidelines. The reference ranges were determined in accordance with the American Society for Veterinary Clinical Pathology. The PT and PTT reference ranges were between 6.06 to 9.32 s and between 15.25 to 24.57 s, respectively.Discussion: The increased activity of the extrinsic pathway clotting factor generates narrow values in the PT assay, in comparison to PTT results.[...](AU)

Valores de Referência para tempos de coagulação em uma população de cães de Porto Alegre, RS, Brasil / Reference values for coagulation time of dogs in Porto Alegre, RS, Brazil

Background: Prothrombin time (PT) and activated partial thromboplastin time (PTT) are screening tests for coagulopathies in dogs. Both tests measure the clotting ability by the activation of different parts of the coagulation cascade. These tests vary widely in terms of reference parameters, mainly due the considerable diversity of reagents and analyzers available. In addition, there are many variations inherent to different populations, and little has been published about coagulation reference parameters for the local dog population. The main objective of the present study was to determine a clotting time reference range of a dog population in Porto Alegre, Rio Grande do Sul, Brazil.Materials, Methods & Results: Hemostatic reference range was determined from citrated plasma of 268 clinically heathy dogs of both genders. The animals did not present bleeding diathesis or thrombocytopenia history. All dogs were previously submitted to clinical examination (cardiopulmonary auscultation, abdominal palpation, and rectal temperature) and laboratory screening (complete blood count, creatinine, albumin, and alanine aminotransferase). PT and PTT of 71 and 258 samples were measured, respectively. Blood samples were collected into 2.7 mL 3.2 % sodium citrate tubes (9 parts blood : 1 part citrate) by vacuum. Blood samples were centrifuged; the plasma was harvested and stored at -30 °C upon analyses. All analyses were performed using the viscosity detection method in semi-automatic coagulometer according to manufacturer’s guidelines. The reference ranges were determined in accordance with the American Society for Veterinary Clinical Pathology. The PT and PTT reference ranges were between 6.06 to 9.32 s and between 15.25 to 24.57 s, respectively.Discussion: The increased activity of the extrinsic pathway clotting factor generates narrow values in the PT assay, in comparison to PTT results.[...]

Transmission of lupus anticoagulant by allogeneic stem cell transplantation.

Passive transmission of autoimmune diseases by allogeneic stem cell transplantation is rare and is ascribed to passive transfer of memory B-cells from donor to recipient. We hereby report a case of transmission of an asymptomatic lupus anticoagulant from a sibling donor to a recipient of transplantation for secondary acute myeloid leukemia. On pre-harvest evaluation, the sibling donor with no history of bleeding or thrombosis was found to have a lupus anticoagulant. After engraftment, the recipient was found to have a new prolonged activated partial thromboplastin time and was subsequently shown to have a lupus anticoagulant on Day +73 after stem cell transplantation. The recipient remained well with no evidence of bleeding, thrombosis, or graft-versus-host disease and was on a stable dose of tacrolimus at the time the lupus anticoagulant was detected. There was no other identifiable trigger for the appearance of a lupus anticoagulant.

Transmission of lupus anticoagulant by allogeneic stem cell transplantation

Passive transmission of autoimmune diseases by allogeneic stem cell transplantation is rare and is ascribed to passive transfer of memory B-cells from donor to recipient. We hereby report a case of transmission of an asymptomatic lupus anticoagulant from a sibling donor to a recipient of transplantation for secondary acute myeloid leukemia. On pre-harvest evaluation, the sibling donor with no history of bleeding or thrombosis was found to have a lupus anticoagulant. After engraftment, the recipient was found to have a new prolonged activated partial thromboplastin time and was subsequently shown to have a lupus anticoagulant on Day +73 after stem cell transplantation. The recipient remained well with no evidence of bleeding, thrombosis, or graft-versus-host disease and was on a stable dose of tacrolimus at the time the lupus anticoagulant was detected. There was no other identifiable trigger for the appearance of a lupus anticoagulant...

Determinación de valores de referencia para pruebas de coagulación en una población pediátrica / Determination of reference ranges for coagulation tests in a pediatric population / Determinação dos valores de referência para provas de coagulação numa população pediátrica

El sistema hemostático varía a lo largo de las primeras etapas de vida ya que el organismo sufre un proceso dinámico de cambios durante el período de crecimiento. En la literatura existen pocos trabajos sobre valores de referencia en niños de pruebas de hemostasia y por ello la importancia de investigar en el tema. El presente es un trabajo retrospectivo que se realizó sobre 512 niños hasta 17 años que concurrieron al hospital con pedido médico de estudio prequirúrgico para cirugías programadas ambulatorias de los cuales se obtuvieron, de sus historias clínicas, los valores de actividad protrombínica del plasma (APP), tiempo de tromboplastina parcialmente activada (aPTT) y fibrinógeno. Los resultados, teniendo en cuenta el percentilo 97,5, mostraron diferencias significativas para la determinación del APP y del aPTT, no observándose diferencias en la prueba del fibrinógeno. Es importante que cada laboratorio establezca sus propios valores de referencia para estas pruebas, ya que no son extrapolables a los de los adultos. En este estudio se demuestra que el sistema hemostático sufre modificaciones durante la infancia que deben ser tenidas en cuenta para interpretar correctamente los resultados de las pruebas realizadas.

The haemostatic system varies throughout the first stages of life since the body undergoes a dynamic process of changes during the growth period. Little research has been conducted on the reference ranges of haemostasis tests in children; therefore, it is of great significance to investigate this subject. The following study is retrospective and it was conducted on 512 children up to 17 years old that attended the hospital requesting presurgical testing for scheduled ambulatory surgeries. Ranges of plasma prothrombin activity (APP), the activated partial thromboplastin time (aPTT) and fibrinogen were obtained from the patients' medical records. Taking into account the 97.5 percentile, the results showed important differences in APP and aPTT determination but showed no differences in the fibrinogen test. It is important that all laboratories establish their own reference ranges for these tests since they cannot be extrapolated to the ones in adults. This study proves that the haemostatic system undergoes significant changes during infancy which shall be taken into account for the correct interpretation of the results of the tests carried out.

O sistema hemostático varia ao longo das primeiras etapas da vida visto que o organismo sofre um processo dinâmico de alterações durante o periodo de crescimento. Na literatura existem poucos estudos sobre valores de referência de testes de hemostasia em crianças e é por esse motivo que é importante pesquisar sobre o assunto. O presente trabalho é retrospectivo e foi realizado em 512 crianças de até 17 anos que assistiram ao hospital com pedido médico de exame pré-cirúrgico para cirurgias ambulatoriais programadas, de cujos prontuários foram obtidos os valores da atividade protrombínica (APP), tempo de tromboplastina parcialmente ativada (aPTT) e fibrinogênio. Os resultados, levando em consideração o percentil 97,5, mostraram diferenças significativas para a determinação do APP e do aPTT, não encontrando diferenças no teste do fibrinogênio. É importante que cada laboratório estabeleça seus próprios valores de referência para estes testes, visto que não se pode extrapolar para os adultos. Neste estudo é demonstrado que o sistema hemostático sofre modificações na infância as quais devem ser consideradas para interpretar corretamente os resultados dos testes realizados.

Determinación de valores de referencia para pruebas de coagulación en una población pediátrica / Determination of reference ranges for coagulation tests in a pediatric population / DeterminaþÒo dos valores de referÛncia para provas de coagulaþÒo numa populaþÒo pediátrica

El sistema hemostático varía a lo largo de las primeras etapas de vida ya que el organismo sufre un proceso dinámico de cambios durante el período de crecimiento. En la literatura existen pocos trabajos sobre valores de referencia en niños de pruebas de hemostasia y por ello la importancia de investigar en el tema. El presente es un trabajo retrospectivo que se realizó sobre 512 niños hasta 17 años que concurrieron al hospital con pedido médico de estudio prequirúrgico para cirugías programadas ambulatorias de los cuales se obtuvieron, de sus historias clínicas, los valores de actividad protrombínica del plasma (APP), tiempo de tromboplastina parcialmente activada (aPTT) y fibrinógeno. Los resultados, teniendo en cuenta el percentilo 97,5, mostraron diferencias significativas para la determinación del APP y del aPTT, no observándose diferencias en la prueba del fibrinógeno. Es importante que cada laboratorio establezca sus propios valores de referencia para estas pruebas, ya que no son extrapolables a los de los adultos. En este estudio se demuestra que el sistema hemostático sufre modificaciones durante la infancia que deben ser tenidas en cuenta para interpretar correctamente los resultados de las pruebas realizadas.(AU)

The haemostatic system varies throughout the first stages of life since the body undergoes a dynamic process of changes during the growth period. Little research has been conducted on the reference ranges of haemostasis tests in children; therefore, it is of great significance to investigate this subject. The following study is retrospective and it was conducted on 512 children up to 17 years old that attended the hospital requesting presurgical testing for scheduled ambulatory surgeries. Ranges of plasma prothrombin activity (APP), the activated partial thromboplastin time (aPTT) and fibrinogen were obtained from the patients medical records. Taking into account the 97.5 percentile, the results showed important differences in APP and aPTT determination but showed no differences in the fibrinogen test. It is important that all laboratories establish their own reference ranges for these tests since they cannot be extrapolated to the ones in adults. This study proves that the haemostatic system undergoes significant changes during infancy which shall be taken into account for the correct interpretation of the results of the tests carried out.(AU)

O sistema hemostático varia ao longo das primeiras etapas da vida visto que o organismo sofre um processo dinÔmico de alteraþ§es durante o periodo de crescimento. Na literatura existem poucos estudos sobre valores de referÛncia de testes de hemostasia em crianþas e é por esse motivo que é importante pesquisar sobre o assunto. O presente trabalho é retrospectivo e foi realizado em 512 crianþas de até 17 anos que assistiram ao hospital com pedido médico de exame pré-cirúrgico para cirurgias ambulatoriais programadas, de cujos prontuários foram obtidos os valores da atividade protrombínica (APP), tempo de tromboplastina parcialmente ativada (aPTT) e fibrinogÛnio. Os resultados, levando em consideraþÒo o percentil 97,5, mostraram diferenþas significativas para a determinaþÒo do APP e do aPTT, nÒo encontrando diferenþas no teste do fibrinogÛnio. E importante que cada laboratório estabeleþa seus próprios valores de referÛncia para estes testes, visto que nÒo se pode extrapolar para os adultos. Neste estudo é demonstrado que o sistema hemostático sofre modificaþ§es na infÔncia as quais devem ser consideradas para interpretar corretamente os resultados dos testes realizados.(AU)

Biological potency evaluation and physicochemical characterization of unfractionated heparins

Unfractionated heparins are used clinically as anticoagulants. The biological potency of thirteen samples of raw material and pharmaceutical formulations were assessed utilizing the 5th International Standard of heparin using the sheep plasma coagulation inhibition assay, activated partial thromboplastin time, anti-factor Xa assay, and anti-factor IIa assay, resulting in mean potencies of 101.15 percent, 96.15 percent, 98.15 percent and 99.37 percent, respectively. The samples were also evaluated by the protamine neutralization test giving results within the range of 92 - 138 IU/mg. The anti-factor IIa assay was performed showing reproducibility and significant correlation with the pharmacopoeial assays, thus demonstrating it to be a feasible alternative to the sheep plasma coagulation inhibition assay. Moreover, an analysis by nuclear magnetic resonance and capillary electrophoresis showed some peaks attributable to oversulfated chondroitin sulfate. The results show that batch-to-batch variations and the quality of samples contributed to improvements in the quality control of pharmaceutical products and to assure the safe use and clinical efficacy of this biological medicine.

As heparinas não fracionadas são utilizadas clinicamente como anticoagulantes. A potência biológica de 13 amostras de matérias-primas e produtos farmacêuticos foram avaliadas em relação ao 5ª Padrão Internacional de heparina pelos ensaios da inibição da coagulação do plasma ovino, tempo de tromboplastina parcial ativada, anti-fator Xa e anti-fator IIa, que forneceram potências médias de 101,15 por cento, 96,15 por cento, 98,15 por cento e 99,37 por cento, respectivamente. As amostras foram também submetidas ao teste de neutralização pela protamina que apresentou resultados entre 92-138 UI/mg. Demonstrou-se reprodutibilidade e correlação significativa do ensaio do anti-fator IIa com os farmacopeicos, constituindo-se em alternativa ao ensaio da inibição da coagulação do plasma ovino. Além disso, as análises realizadas por ressonância magnética nuclear e eletroforese capilar mostraram picos correspondentesà condroitina supersulfatada. Os resultados mostraram variações lote-a-lote e a qualidade das amostras contribuindo para aprimorar o controle de qualidade dos produtos farmacêuticos e garantir a segurança e eficácia terapêutica desses produtos biológicos.

Anticoagulante Lúpico: Sensibilidad de 19 reactivos comerciales de tiempo de tromboplastina parcial activado / Lupus Anticoagulant: Sensitivity of 19 commercial activated partial thromboplastin time reagents

El Anticoagulante Lúpico (AL) constituye una familia de inmunoglobulinas que interfieren las pruebas de coagulación dependientes de fosfolípidos. Hay una gran variedad de pruebas que permiten detectar y confirmar la presencia de AL en el plasma de un paciente. Sin embargo, el tiempo de tromboplastina parcial activado (TTPA) sigue siendo una de las pruebas más utilizadas para la detección de dicho inhibidor. Teniendo en cuenta la importancia clínica de su diagnóstico de laboratorio, se dicidió estudiar la sensibilidad, para detectar AL, de 19 reactivos comerciales de TTPA. Se obtuvieron varias conclusiones importantes: No se encontró relación entre sensibilidad y tamaño de los liposomas; tampoco con la uniformidad de los mismos. La fuente de fosfolípido y el tipo de activador no son suficientes para explicar las diferencias en sensibilidad de los reactivos. Finalmente, se encontró una correlación negativa entre la sensibilidad y la concentración total de fosfolípido del reactivo. A menor concentración de fosfolípido, mayor sensibilidad.

Lupus anticoagulants (LA) are immunoglobulins which interfere in in vitro phospholipid-dependent coagulation tests. Various methods have been proposed; however, activated partial thromboplastin time (APTT) is the most used screening test for lupus anticoagulant. Previous studies have shown that sensitivity to the lupus anticoagulant defect varies considerably with different APTT reagents. In view of the undoubted clinical importance of lupus anticoagulants, the sensitivity of 19 commercial APTT reagents has been evaluated. The study raises several important conclusions: No difference was found in sensitivity associated with a narrower distribution of liposomes' diameter, considering the latter as a marker of uniformity in phospholipid distribution. The source of the platelet substitute and the nature of the contact phase activator are unlikely to determine such varied sensitivity. Finally, a significant negative correlation between APTT sensitivity and total phospholipid concentration was found. The lower the phospholipid concentration, the higher the APTT sensitivity to AL.

Estudo da cascata de coagulação sangüínea e seus valores de referência / Study of blood coagulation cascade and the reference values

Um vaso sanguíneo lesado inicia um processo denominado hemostasia. A coagulação envolve uma sequência de reações interligadas, a cascata de coagulação, dividido na via extrínseca em resposta ao contato do sangue com os tecidos extravasculares e na via intrínseca pelo contato do sangue com uma superfície diferente do endotelio normal e das células sanguíneas. O tempo de protrombina (TP) é o tempo necessário para que ocorra a coagulação, nos fatores envolvidos no sistema extrínseco. O tempo tromboplastina parcial ativado (TTPA) é empregado para verificação do mecanismo intrínseco da coagulação. A avaliação da cascata de coagulação é revisada neste trabalho.

A harmed blood vessel begins a process denominated hemostasis. The coagulation involves a sequence of interlinked reactions, the coagulation cascade, divided in the extrinsic pathway in response to the blood contact with the extravascular tissues and in the intrinsic pathway for the blood contact with a different surface from the normal endothelium and the blood cells. Prothrombin time (PT) is the time needed to occur the coagulation, in the factors involved in the extrinsic system. Activated partial thromboplastin time (APTT) is used for verification of the coagulation intrinsic mechanism. The evaluation of coagulation cascade is reviewed in this work.