Rivaroxaban Levels in Patients' Plasmas are Comparable by Using Two Different Anti Xa Assay/Coagulometer Systems Calibrated with Two Different Calibrators.

BACKGROUND: Rivaroxaban oral anticoagulant does not need laboratory monitoring, but in some situations plasma level measurement is useful. The objective of this paper was to verify analytical performance and compare two rivaroxaban calibrated anti Xa assays/coagulometer systems with specific or other branch calibrators. METHODS: In 59 samples drawn at trough or peak from patients taking rivaroxaban, plasma levels were measured by HemosIL Liquid anti Xa in ACLTOP 300/500, and STA liquid Anti Xa in TCoag Destiny Plus. HemosIL and STA rivaroxaban calibrators and controls were used. CLSI guideline procedures EP15A3 for precision and trueness, EP6 for linearity, and EP9 for methods comparison were used. RESULTS: Coefficient of variation within run and total precision (CVR and CVWL respectively) of plasmatic rivaroxaban were < 4.2 and < 4.85% and BIAS < 7.4 and < 6.5%, for HemosIL-ACL TOP and STA-Destiny systems, respectively. Linearity verification 8 - 525 ng/mL a Deming regression for methods comparison presented R 0.963, 0.968 and 0.982, with a mean CV 13.3% when using different systems and calibrations. CONCLUSIONS: The analytical performance of plasma rivaroxaban was acceptable in both systems, and results from reagent/coagulometer systems are comparable even when calibrating with different branch material.

[Renal function and plasma dabigatran level measured at trough by diluted thrombin time assay]. / Función renal y nivel plasmático de dabigatrán en el valle, medido por un ensayo de trombina diluida.

Dabigatran etexilate (direct thrombin inhibitor) is effective in preventing embolic stroke in patients with atrial fibrillation. It does not require laboratory control, but given the high renal elimination, its measurement in plasma is important in renal failure. The objectives of the study were to verify the analytical quality of the diluted thrombin time assay for measurement of dabigatran plasma concentration (cc), correlate cc with classic coagulation assays, prothrombin time (PT) and activated partial thromboplastin time (APTT), and evaluate them according to the creatinine clearance (CLCr). Forty plasma samples of patients (34 consecutive and 6 suspected of drug accumulation) receiving dabigatran at 150 (n = 19) or 110 (n = 21) mg/12 hours were collected. Blood samples were drawn at 10-14 hours of the last intake. Dabigatran concentration was determined by diluted thrombin time (HemosIl DTI, Instrumentation Laboratory (IL). PT and APTT (IL) were performed on two fotooptical coagulometers, ACL TOP 300 and 500 (IL). DTI presented intra-assay coefficient of variation < 5.4% and inter-assay < 6%, linearity range 0-493 ng/ml. Patients' cc: median 83 (4-945) ng/ml. Individuals with CLCr in the lowest tertile (22.6-46.1 ml/min) showed significantly higher median cc: 308 (49-945), compared to the average 72 (12-190) and highest tertile, 60 (4-118) ng/ml. Correlation between cc and APTT or PT were moderate, r2 = 0.59 and -0.66, p < 0.0001, respectively. DTI test allowed us to quantify plasma dabigatran levels, both in patients with normal or altered renal function, representing a useful tool in clinical situations such as renal failure, pre surgery or emergencies.

Validation of an Automated Immunoturbidimetric Assay for Fibrinogen/Fibrin Degradation Products Measurement and its Correlation to a Semi-Quantitative Latex Agglutination Test.

BACKGROUND: Laboratory determination of fibrinogen/fibrin degradation product (FDP) levels is important as a hyperfibrinolytic state marker. The aim of the study was to verify the analytical performance of an automated immunoturbidimetric assay (AIMT) for FDP and its comparison to a latex agglutination semiquantitative (SLAT) test. METHODS: Total precision and accuracy was calculated following the EP 15-A2 protocol at two levels of controls. The protocol EP6 was performed for linearity. For semi-quantitative methods comparison, 71 consecutive samples were used. Concordance between methods results in term of positive and negative, and in categories, from <10 to > 160 µg/mL, was calculated through Cohen kappa coefficient (). RESULTS: Total CV%: low control (10.8 µg/mL) 8.0 and 3.7 vs. 4.8 and high control (31.3 µg/mL) 2.7 and 3.8 vs. 3.6, for coagulometer ACL TOP 500 and 300 vs. manufacturer claimed, respectively. Linearity between 0 and 125 µg/mL showed polynomial fit analysis applicable. When correlating AIMT to SLAT, a good concordance was observed:  of results expressed as positive-negative = 79.5% with 90.1% of agreement (p < 0.001), of results expressed as categories = 72.2% (p < 0.001) with 80.3% concordance. CONCLUSIONS: AIMT presented good analytical performance, and the concordance with SLAT by comparison of patients' samples results was also good. The implementation of IMMT in the clinical laboratory is suitable and reliable.

[Levels of antiplatelet factor 4-heparin antibodies and 4T score for heparin induced thrombocytopenia]. / Los niveles de anticuerpos anti factor plaquetario 4-heparina y el índice 4T para trombocitopenia inducida por heparina.

Heparin induced thrombocytopenia (HIT) is an immune-mediated disorder due to antibodies anti platelet factor 4-heparin (HPIA). Thrombocytopenia is often moderate but certain patients can develop morbid thrombotic complications. HPIA detection by ELISA has high sensitivity but low specificity, and low titers (without clinical significance) are frequent. A pretest clinical score (4T's) was developed in order to recognize patients that are at high risk of HIT. The aim of this study was to correlate HPIA levels and the 4T's score of consecutive patients derived to our center. We evaluated 84 patients (35 of them developed thrombosis); the clinical questionnaire was sent along with the sample and was analyzed by an investigator who did not know the patients' characteristics, and 4T's scores were calculated before performing the laboratory tests. HPIA were measured by ELISA (Asserachrom HPIA) that detects IgG, IgM and IgA isotypes, (the only reagent available in our country). 4T's score correlated with HPIA levels (rho spearman 0.472, p < 0.001). Patients with 4T's = 6 had higher absorbance percentages than those with = 5 (67 vs. 39%, p < 0.001), and patients with thrombosis also presented higher titers (59 vs. 39%, p = 0.017) than those who did not develop this complication. In conclusion, high titers of HPIA measured by EIA which detects the 3 isotypes, clearly correlate with 4T's score = 6 and are more frequent in patients who develop thrombosis, just as reported when an IgG specific ELISA is used.

Nonimmune-acquired factor XIII deficiency: a cause of high volume and delayed postoperative hemorrhage.

: Factor XIII (FXIII) levels may decrease because of surgical consumption. Acquired FXIII deficiency could be a cause of postoperative hemorrhage usually underdiagnosed in clinical practice. To determine the diagnosis confirmation rate of acquired FXIII deficiency in postsurgical patients with clinical suspicion and to compare the characteristics and evolution of patients with or without FXIII deficiency. We performed a retrospective cohort study, which included 49 inpatients who were attended at our university hospital from 2014 to 2018 with suspicion of acquired FXIII deficiency because of disproportionate postoperative hemorrhage. FXIIIA levels less than 50% was considered a deficiency. Persistence of bleeding for more than 48 h, drop in hematocrit points, red blood cells transfused units, hemoglobin levels 12-36 h after bleeding, and time elapsed from the procedure to the bleeding were assessed as outcome variables. Logistic regression was employed for both univariate and multivariate analyses. Of the 49 patients included, 27(55%) had FXIII deficiency, with a median level of 34% [interquartile range (IQR) 19-42]. Abdominal surgery was the most common [n = 21 (43%)]. All patients had routine coagulation tests within the hemostatic range. FXIII deficiency was associated with a drop of more than 4 points in hematocrit [OR 59.69 (95% CI 4.71-755.30)], red blood transfused units >2 [OR 45.38 (95% CI 3.48-590.65)], and delayed bleeding >36 h after surgery [OR 100.90 (95% CI 3.78-2695.40)]. Plasma-derived FXIII concentrate was administered to eight patients with life-threatening bleeding with resolution within 24 h. Only one deficient patient died from bleeding. FXIII levels were measured 15 days after diagnosis or more in 20 out of 27 deficient patients, with normal results. Acquired FXIII deficiency may be a frequent underdiagnosed entity that should be considered when high-volume and delayed postoperative hemorrhage is present in patients with hemostatic routine coagulation test results.

Función renal y nivel plasmático de dabigatrán en el valle, medido por un ensayo de trombina diluida / Renal function and plasma dabigatran level measured at trough by diluted thrombin time assay

El dabigatrán etexilato (inhibidor directo de trombina) es eficaz en la prevención tromboembólica en pacientes con fibrilación auricular. No requiere control rutinario de laboratorio, pero dada su eliminación renal, sería importante medirlo ante el deterioro de la función renal. Los objetivos del trabajo fueron verificar la calidad analítica del ensayo tiempo de trombina diluido para medición de la concentración plasmática (cc) de dabigatrán, correlacionar las cc con las pruebas básicas de coagulación tiempo de protrombina (TP) y tiempo de tromboplastina parcial activada (APTT) y evaluarlas de acuerdo al clearance de creatinina (CLCr). Se utilizaron muestras de plasma de 40 pacientes que recibían dabigatrán 150 (n = 19) o 110 (n = 21) mg/12 horas, colectadas 10-14 horas después de la última toma. Los ensayos de trombina diluida HemosIL DTI para la medición de dabigatrán, TP y APTT (IL), fueron realizados en coagulómetros fotoópticos ACL TOP 300 y 500 (IL). El DTI presentó coeficiente de variación intraensayo < 5.4% e interensayo < 6.0%, rango de linealidad 0-493 ng/ml; cc medidas en pacientes: mediana 83 (4-945) ng/ml. Individuos con CLCr en tercil inferior (< 46.1 ml/min) presentaron cc significativamente más elevadas, 308 (49-945), que los de tercilos medio, 72 (12-190), y superior, 60 (4-118) ng/ml. Las correlaciones cc vs. APTT o TP fueron moderadas, r2 = 0.59, -0.66, p < 0.0001, respectivamente. La prueba ensayada permitió cuantificar el nivel de dabigatrán plasmático tanto en pacientes con función renal normal como deteriorada, representando una herramienta útil en situaciones clínicas como deterioro de la función renal, pre cirugía o emergencias.

Dabigatran etexilate (direct thrombin inhibitor) is effective in preventing embolic stroke in patients with atrial fibrillation. It does not require laboratory control, but given the high renal elimination, its measurement in plasma is important in renal failure. The objectives of the study were to verify the analytical quality of the diluted thrombin time assay for measurement of dabigatran plasma concentration (cc), correlate cc with classic coagulation assays, prothrombin time (PT) and activated partial thromboplastin time (APTT), and evaluate them according to the creatinine clearance (CLCr). Forty plasma samples of patients (34 consecutive and 6 suspected of drug accumulation) receiving dabigatran at 150 (n = 19) or 110 (n = 21) mg/12 hours were collected. Blood samples were drawn at 10-14 hours of the last intake. Dabigatran concentration was determined by diluted thrombin time (HemosIl DTI, Instrumentation Laboratory (IL). PT and APTT (IL) were performed on two fotooptical coagulometers, ACL TOP 300 and 500 (IL). DTI presented intra-assay coefficient of variation < 5.4% and inter-assay < 6%, linearity range 0-493 ng/ml. Patients´ cc: median 83 (4-945) ng/ml. Individuals with CLCr in the lowest tertile (22.6-46.1 ml/min) showed significantly higher median cc: 308 (49-945), compared to the average 72 (12-190) and highest tertile, 60 (4-118) ng/ml. Correlation between cc and APTT or PT were moderate, r2 = 0.59 and -0.66, p < 0.0001, respectively. DTI test allowed us to quantify plasma dabigatran levels, both in patients with normal or altered renal function, representing a useful tool in clinical situations such as renal failure, pre surgery or emergencies.

Los niveles de anticuerpos anti factor plaquetario 4-heparina y el índice 4T para trombocitopenia inducida por heparina / Levels of antiplatelet factor 4-heparin antibodies and 4T score for heparin induced thrombocitopenia

La trombocitopenia inducida por heparina (HIT) es un efecto adverso del tratamiento con heparina, mediada por anticuerpos anti complejo factor plaquetario 4 (PF4)-heparina (HPIA). La HIT es frecuentemente moderada pero pueden desarrollarse complicaciones trombóticas. El diagnóstico precoz es importante. La detección de HPIA por ELISA tiene alta sensibilidad pero baja especificidad (títulos bajos sin significación clínica). El índice de las 4T (índice 4T) puede detectar pacientes con alto riesgo de HIT. El propósito del estudio fue correlacionar los niveles de HPIA y el índice 4T de un grupo de pacientes derivados a nuestro centro. Evaluamos 84 pacientes, 34 de ellos desarrollaron trombosis. Cada médico completó un cuestionario clínico que fue remitido con la muestra a nuestro centro. Los cuestionarios fueron analizados por un investigador externo y el índice 4T se calculó previamente al ensayo. Los HPIA se determinaron por un ELISA (Asserachrom HPIA) que detecta los 3 isotipos, IgG, IgM e IgA, único reactivo disponible en Argentina. Los resultados se expresaron como porcentaje de absorbancia (%ABS). La correlación del índice 4T con los HPIA fue 0.472 (rho spearman, p < 0.001). Los pacientes con índice 4T ≥ 6 presentaban %ABS mayores que los ≤ 5 (67 vs. 39, p < 0.001). Aquéllos con trombosis presentaron títulos mayores que los que no la desarrollaron (%ABS 59 vs. 39, p = 0.017). En conclusión: Los títulos altos de HPIA medidos por ELISA, que detecta los 3 isotipos, correlacionaron claramente con el índice 4T ≥ 6 y fueron más frecuentes en los pacientes con trombosis, coincidiendo con lo ya descripto para ensayos de ELISA específicos para isotipo IgG.

Heparin induced thrombocytopenia (HIT) is an immune-mediated disorder due to antibodies anti platelet factor 4-heparin (HPIA). Thrombocytopenia is often moderate but certain patients can develop morbid thrombotic complications. HPIA detection by ELISA has high sensitivity but low specificity, and low titers (without clinical significance) are frequent. A pretest clinical score (4T´s) was developed in order to recognize patients that are at high risk of HIT. The aim of this study was to correlate HPIA levels and the 4T´s score of consecutive patients derived to our center. We evaluated 84 patients (35 of them developed thrombosis); the clinical questionnaire was sent along with the sample and was analyzed by an investigator who did not know the patients´ characteristics, and 4T´s scores were calculated before performing the laboratory tests. HPIA were measured by ELISA (Asserachrom HPIA) that detects IgG, IgM and IgA isotypes, (the only reagent available in our country). 4T´s score correlated with HPIA levels (rho spearman 0.472, p < 0.001). Patients with 4T´s ≥ 6 had higher absorbance percentages than those with ≤ 5 (67 vs. 39%, p < 0.001), and patients with thrombosis also presented higher titers (59 vs. 39%, p = 0.017) than those who did not develop this complication. In conclusion, high titers of HPIA measured by EIA which detects the 3 isotypes, clearly correlate with 4T´s score ≥ 6 and are more frequent in patients who develop thrombosis, just as reported when an IgG specific ELISA is used.

Evaluación de polimorfismos genéticos protrombóticos y alteraciones del sistema fibrinolítico en mujeres con historia de complicaciones obstétricas / Prothrombotics Evaluation of genetic polymorphisms and fibrinolytic system alterations in women with a history of obstetric complications

La presencia de polimorfismos protrombóticos y algunas alteraciones fibrinolíticas han sido descriptas en las pacientes con pérdidas de embarazos (PE) recurrentes si bien no hay datos concluyentes al respecto y menos aún en pacientes con falla de implantación. El objetivo del trabajo fue en primer lugar analizar la prevalencia de 3 polimorfismos protrombóticos [Factor V Leiden, Polimorfismo del gen de la Protrombina 20210 (PT 20210) y polimorfismo del promotor del PAI 1 (4G5G)] en 147 pacientes con historia de PE comparados con un grupo control de mujeres sanas con historia de embarazos sin complicaciones. En segundo lugar, analizar la correlación entre 3 pruebas del sistema fibrínolítico: PAI 1 inmunológico, Lisis de euglobulinas (LE) pre y post isquemia y polimorfismo del PAI 1 4G5G en un grupo de 92 mujeres con historia de PE (n=49) o fallas de implantación (FI) post procedimientos de fertilización in vitro ( n=43). La prevalencia de los polimorfismos protrombóticos estudiados en las pacientes no fue significativamente diferente de la hallada en el grupo control normal, excepto para el Factor V Leiden en PE tardías (p=0.03) y sólo una tendencia para el PAI 4G4G en abortos tempranos recurrentes (p=0.08). La respuesta en la LE post isquemia fue mala en el 17.4% y ligeramente alterada en el 19.3%. Considerando a la población total de 92 mujeres con complicaciones obstétricas, no existió relación entre los niveles de PAlIo la respuesta fibrinolitica a la isquemia con el genotipo del promotor del PAI. Los niveles de PAI 1 estuvieron significativamente más elevados en las mujeres que presentaban factores de riesgo clásico de enfermedad cardiovascular (32.46 vs. 20.6 ng/rol, p=0.023), y esto fue especialmente debido al grupo de portadoras del genotipo homocigota 4G4G. Los niveles de PAI 1 y las LE pre y post isquemia presentaron correlación positiva con el índice de masa corporal...

La prolongación del tiempo de protombina diluído (dTP) a baja concentración de iones calcio no identifica a todos los anticoagulantes lúpicos (AL) asociados a anticuerpos anti beta2 glicoproteína I (abeta2GPI) / Diluted propagation time with calcium ions low concentration did not identidie all lupic anticoagulant associated to anti beta 2 glycoprotein antibodies

En la literatura se describió que la prolongación de las pruebas de coagulación a baja concentración de ionescalcio se asociaba a la presencia de a132GPI en un pequeño grupo seleccionado de pacientes con anticoagulante lúpico (AL). Por ello se decidió evaluar la respuesta ala disminución en la concentración de calcio de los plasmas obtenidos de 318 pacientes consecutivos derivados a nuestro laboratorio para la investigación de AL. Se realizó el tiempo de protrombina diluido (dTP) utilizando una dilución 1:50 de tromboplastina recombinante a 2 concentraciones finales de calcio 15 y 5 mM. Se calculó el cociente P:N a ambas concentraciones y luego una relación de esos cocientes (razón 5:15). Setenta y cinco de 318 presentaron AL positivo. De los mismos, aquellos que presentaban a132GPI prolongaban significativamenteel dTP a bajas concentraciones de calcio: media de cocientes P:N 2.43 v s 2.96 a 15 y 5 m M respectivamente,p=0.05. Una prolongación mayor de120 porciento (razón 5:15 >1.2) se presentó en el 47.7 porciento de los pacientes con AL (+) y a132GPI (+) comparado con un 16.2 porciento de los pacientes AL (+) a132GPI (-), p=0.0014. Se observó que la presencia de a132GPI estaba asociada a la prolongación del dTP a bajas concentraciones de iones calcio, no obstante la sensibilidad de la prueba para identificar los AL asociados a a132GPI es baja.