Clotting factor levels and the risk of diffuse microvascular bleeding in the massively transfused patient

Clotting factor activities and coagulation screening tests in 36 massively transfused patients were measured after every 12 units of blood and whenever diffuse microvascular bleeding (MVB) developed. Moderate deficiencies in clotting factors were common, but they were not associated with MVB. MVB was associated with severe abnormalities of coagulation, i.e. a fibrinogen level less than 0.5 g/l or clotting factor levels less than 20%. The quantitative relationship between the prothrombin (PT) and partial thromboplastin (PTT) times and underlying clotting factor levels was explored by multiple linear regression. Clotting factor levels accounted for only 65-85% of the variability in these tests. However, clotting factor activities less than 20% were reliably reflected by marked prolongations of the PT and PTT (values greater than 1.8 times control). Our data suggest that commonly used replacement formulas are not likely to prevent MVB, since consumption of platelets and/or clotting factors, rather than simple dilution, is a major cause of the deficiencies leading to MVB. Modified whole blood alone was sufficient replacement therapy for most patients. Guidelines for transfusion of supplemental components during massive transfusion are given.     

Inactivation of factor Xa by the synthetic inhibitor DX-9065a causes strong anticoagulant and antiplatelet actions in human blood.

In an in vitro study, anticoagulant and antiplatelet effects of the synthetic, direct factor Xa inhibitor DX-9065a, (+)-2S-2-[4-[[(3S)-1-acetimidoyl-3-pyrrolidinyl]oxy]phenyl]-3-[7-a midino-2-naphthyl]propanoic acid hydrochloride pentahydrate, which shows a high affinity and selectivity towards the enzyme, were investigated. Anticoagulant actions of DX-9065a were studied in human plasma using global clotting assays [prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and Heptest]. The effect on thrombin generation was measured in whole blood by determining the plasma concentration of prothrombin fragment F1.2. The influence on agonist-induced platelet activation in whole blood was studied using flow cytometric analysis. DX-9065a caused a concentration-dependent prolongation of clotting times in the PT and APTT assay, whereas Heptest was less affected and TT was not influenced. Furthermore, DX-9065a strongly inhibited the generation of thrombin without and after coagulation activation. The factor Xa inhibitor did not affect platelet activation mediated by either thrombin receptor activating peptide, arachidonic acid or y-thrombin, but prevented tissue factor- and factor Xa-induced activation of platelets in a concentration-dependent manner. Inactivation of factor Xa by a highly effective and selective inhibitor, and the resulting inhibition of thrombin generation leads to strong anticoagulant and antiplatelet actions. The interference with the coagulation system at the early level of factor Xa is expected to be an effective approach for a successful anticoagulant/antithrombotic therapy.     

联合输注新鲜冰冻血浆和冷沉淀凝血因子的止血效果观察

目的:探讨联合输注新鲜冰冻血浆(FFP)和冷沉淀凝血因子用于肝肿瘤术后凝血功能异常患者的止血效果。方法:将120例肝肿瘤术后凝血功能异常患者随机分为3组:FFP单独输注组、冷沉淀凝血因子单独输注组及FFP和冷沉淀凝血因子联合输注组,每组各40例。所有患者住院期间均行肝肿瘤切除术,术后进行常规治疗,联合或单独输注FFP和冷沉淀凝血因子,3组分别于输注前1h及输注后24h静脉采血,检测输注前后凝血酶原时间(PT)、部分凝血活酶时间(APTT)、凝血酶时间(TT)和纤维蛋白原(FIB)。结果:3组输注后PT、APTT、TT、FIB和输注前1h比较均差异有统计学意义(均P0.01);与2个单独输注组比较,联合输注组PT、APTT、TT数值均差异有统计学意义(均P0.05),FIB数值与FFP单独输注组比较也有明显提高(P0.05)。结论:联合或单独给肝肿瘤术后凝血功能异常患者进行输注均能改善患者的凝血功能,联合输注的止血效果要好于单独输注一种成分。     

Effects of α-tocopherol on platelets and the coagulation system

Vitamin E is one of the most widely used antioxidants in cryopreservation and preservation technology. The objective of this study is to examine the effect of vitamin E on platelets and the coagulation system. Vitamin E was added at different concentrations in the range between 0.25 and 5 mM to donor plasma. Using a STA/STA Compact coagulation analyzer the following clotting tests were performed: prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT). The control clotting times PT (13.80 - 0.4 s), APTT (27.4 - 2.4 s) and TT (17.6 - 0.4 s) remained unchanged in the presence of vitamin E. The effect of vitamin E on platelets was assessed by platelet-induced clot retraction (PICR) and aggregation by thrombin. PICR was unaffected by vitamin E. Platelet aggregation, however, was profoundly inhibited by vitamin E. We found that inhibition of platelet aggregation by vitamin E was concentration dependent: increasing with increasing vitamin E concentration. This inhibitory effect, however, was widely reversible upon dilution of vitamin E with autologus platelet-poor plasma.     

Laboratory measurement of the non-vitamin K antagonist oral anticoagulants: selecting the optimal assay based on drug,assay availability,and clinical indication

Although the non-vitamin K antagonist oral anticoagulants (NOACs) do not require routine monitoring, there are special circumstances in which laboratory measurement may be warranted. The objectives of this review are to summarize evidence on the influence of the NOACs on coagulation tests and provide practical guidance to clinicians on measurement and interpretation of coagulation assays in NOAC-treated patients. Selection of an appropriate assay for NOAC measurement depends on the drug, clinical objective, and assay availability. Separate suggestions for assay selection are provided depending on whether specialized assays are available or whether choice is limited to conventional coagulation assays such as the prothrombin time (PT) and activated partial thromboplastin time (APTT). The dilute thrombin time (TT) and ecarin-based assays are able to quantify dabigatran across a broad range of concentrations, but are not widely available. A normal TT excludes clinically relevant levels. A normal APTT probably excludes excess levels of dabigatran, but does not rule out typical on-therapy drug concentrations. The PT is insufficiently sensitive to dabigatran to be useful in most situations. Factor Xa inhibitors may be quantified with an anti-Xa assay calibrated with drug-specific standards. A normal PT probably excludes excess levels of rivaroxaban and edoxaban, but not typical on-therapy levels of these agents. The PT is less sensitive to apixaban. Depending on the sensitivity of the thromboplastin reagent, a normal PT may not exclude excess levels of apixaban. The APTT has inadequate sensitivity to factor Xa inhibitors and is not recommended for their measurement.     

Alteration in the laboratory profile of a lupus anticoagulant in a patient with non‐Hodgkin's lymphoma

We describe a patient with non‐Hodgkin's lymphoma who developed a lupus anticoagulant (LA) detectable by activated partial thromboplastin time (APTT), dilute Russell's viper venom time (DRVVT) and kaolin clotting time (KCT). IgM anticardiolipin antibodies (ACA) were elevated. At a later admission, and following treatment for the lymphoma, routine coagulation screening showed an elevated prothrombin time (PT) without correction in mixing tests using a recombinant thromboplastin. Routine APTT was below the reference range and ACA levels were normal. Raw data for one‐stage factor assays demonstrated the presence of an inhibitor. Analysis for LA was undertaken by DRVVT, KCT, activated seven lupus anticoagulant assay, Taipan snake venom time, platelet neutralisation procedures (PNP), Ecarin time and PT using rabbit brain thromboplastin. The results revealed a LA capable of prolonging the clotting times of the PNPs and PT using recombinant thromboplastin, but that was corrected using Ecarin venom, modified PNP and brain thromboplastin. The antibody also demonstrated the lupus anticoagulant co‐factor effect. The factor VIII : C was markedly raised which may have masked the LA in the APTT. The changing laboratory profile over time demonstrates the effects of LA heterogeneity and variations in sensitivity and specificity of assays for the detection of antiphospholipid antibodies.     

Alteration in the laboratory profile of a lupus anticoagulant in a patient with non-Hodgkin's lymphoma

We describe a patient with non-Hodgkin's lymphoma who developed a lupus anticoagulant (LA) detectable by activated partial thromboplastin time (APTT), dilute Russell's viper venom time (DRVVT) and kaolin clotting time (KCT). IgM anticardiolipin antibodies (ACA) were elevated. At a later admission, and following treatment for the lymphoma, routine coagulation screening showed an elevated prothrombin time (PT) without correction in mixing tests using a recombinant thromboplastin. Routine APTT was below the reference range and ACA levels were normal. Raw data for one-stage factor assays demonstrated the presence of an inhibitor. Analysis for LA was undertaken by DRVVT, KCT, activated seven lupus anticoagulant assay, Taipan snake venom time, platelet neutralisation procedures (PNP), Ecarin time and PT using rabbit brain thromboplastin. The results revealed a LA capable of prolonging the clotting times of the PNPs and PT using recombinant thromboplastin, but that was corrected using Ecarin venom, modified PNP and brain thromboplastin. The antibody also demonstrated the lupus anticoagulant co-factor effect. The factor VIII: C was markedly raised which may have masked the LA in the APTT. The changing laboratory profile over time demonstrates the effects of LA heterogeneity and variations in sensitivity and specificity of assays for the detection of antiphospholipid antibodies.     

The effects of hypothermia on fibrinogen metabolism and coagulation function in swine

Clinical coagulopathy frequently occurs in the presence of hypothermia. The primary purpose of this study was to investigate the effects of hypothermia on clotting protein fibrinogen metabolism and on coagulation function in a swine model. Twelve pigs were randomly allocated into control and hypothermia groups. Hypothermia of 32 degrees C was induced using a blanket with circulating water at 4 degrees C. Fibrinogen synthesis and breakdown were quantified using a 6-hour stable isotope infusion with subsequent gas chromatograph and mass spectrometry analysis. Clotting enzyme thrombin generation kinetics was quantified at baseline and at the end of the infusion. Changes in fibrinogen metabolism and thrombin generation were correlated with coagulation function assessed by thromboelastography (TEG). Hypothermia decreased fibrinogen synthesis from the control value of 2.6 +/- 0.4 to 1.2 +/- 0.2 mg kg(-1) h(-1) (P < .05), with no effect on fibrinogen breakdown. Thrombin generation at the initiation phase was delayed by hypothermia, but there were no changes at the propagation phase. In thromboelastography measurements, the initial clotting time (R time) was prolonged from the baseline value of 3.01 +/- 0.13 to 4.30 +/- 0.24 minutes (P < .05) and clotting rapidity (angle alpha) was decreased from the baseline value of 72.30 +/- 0.90 to 65.34 +/- 1.07 (P < .05). Hypothermia caused no significant changes in clot strength (maximum amplitude) and clot lysis (LY(60)). We concluded that hypothermia caused a potential deficit in fibrinogen availability and a delay in thrombin generation, consequently inhibiting coagulation function. Our data support the current practices of rewarming and prescribing recombinant factor VIIa for hypothermic patients with coagulation defects.     

晚期血吸虫病肝硬化患者凝血功能检测分析

目的 对比检测晚期血吸虫病与慢性血吸虫病患者的凝血指标,探讨晚血病人的凝血功能机制,及时监测晚血病人的出血倾向并为临床指导用药提供依据。方法 运用国产雷杜RT-2204C 血凝仪检测37 例晚血病人和80 例慢血病人的血浆凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）和凝血酶时间（TT）。结果 晚血病人PT、APTT 和TT 值均大于慢血病人,差异有统计学意义（P 均<0.01）。结论 晚血患者凝血功能明显异常,处于低凝状态且纤溶系统受损,检测该指标对监测晚血病人出血倾向与指导临床用药具有重要的意义。     

Effect of taurine on platelets and the plasma coagulation system

It is not yet clear what exact mechanisms are at work in hibernating animals that prevent clot formation and maintain tissue perfusion under conditions of very slow blood flow and increased blood viscosity brought about by the low temperatures. It has been shown that the total amino acid pool increases more then two fold in hibernating animals with taurine accounting for about 50% of this increase [Storey et al., Proc Natl Acad Sci USA 1988; 85(21): 8350-4]. This work investigates the effect of taurine on platelets and the plasma coagulation system. Taurine was added at different concentrations in the range between 5 and 25 mM to donor plasma. Using STA/STA Compact coagulation analyzer the following tests were performed: prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT). At the highest concentration tested (25 mM) taurine prolonged TT by 9%. The prolongation was statistically significant but not clinically significant retaining TT within normal limits (16.7-20.7 s). PT and APTT remained unchanged by taurine. The effect of taurine on platelets was assessed by platelet aggregation by thrombin, extent of platelet shape change (ESC) induced by ADP, and thrombelastography. Taurine at 5 mM final concentration inhibited platelet aggregation by 10%. Increasing taurine concentration to 25 mM did not result in a further augmentation of the inhibitory effect. ESC was unaffected by taurine. Clot strength determined by thrombelastography also remained unchanged by taurine.     

肝硬化患者凝血功能检测分析

目的分析肝硬化患者凝血指标随肝功能损害程度的变化,并探讨其临床意义。方法测定肝硬化组（50例）和对照组（40例）血浆凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）、凝血酶时间（TT）和纤维蛋白原（FIB）。结果肝硬化组凝血指标与对照组比较,PT、APTT、TT均明显延长,差异有显著统计学意义（P〈0.01）,FIB明显下降,差异有统计学意义（P〈0.05）。肝硬化失代偿组PT、APTT、TT及FIB与代偿组比较,差异有显著统计学意义（P〈0.01）。结论凝血指标可以客观准确的评价肝硬化患者的凝血功能,能够发现早期肝病造成的凝血机制障碍,对肝硬化出血患者的抢救和治疗具有重要意义。     

A step change in oral anticoagulation: lack of coagulation monitoring with ximelagatran

The clinical development of ximelagatran for the treatment and prevention of various arterial and venous thromboembolic disorders has used fixed-dose regimens without coagulation monitoring in all indications. Although monitoring is not required, effects on the various coagulation assays that are available are seen with its active form melagatran, and there are situations where an assessment of anticoagulant effect may help to inform clinical decisions. However, the sensitivity of different coagulation assays varies considerably. The thrombin clotting time (TT) and ecarin clotting time (ECT) are highly sensitive to plasma melagatran concentrations (IC 50 approximately 0.01 micromol/L and approximately 0.15 micromol/L, respectively), with an approximate linear relationship between plasma melagatran concentration and prolongation of clotting time. In comparison, the activated partial thromboplastin time (APTT) (IC 50 approximately 0.3 to 0.8 micromol/L) and prothrombin time (PT) (IC 50 approximately 0.9 to 2.9 micromol/L) are relatively insensitive, and the concentration-response relationship shows a flattening with increasing plasma melagatran concentration. Commercially available APTT and PT reagents varied considerably in their sensitivity to melagatran. Comparing the various coagulation assays, the APTT, ECT, and TT are suitable choices when an indicator of the anticoagulant effect of ximelagatran is required, although the absence of international standards requires calibration of each test in individual laboratories and the ECT is not widely available.     

Effects of levothyroxine treatment on biochemical and hemostasis parameters in patients with hypothyroidism

OBJECTIVE: The aims of the study were to evaluate the disturbances in the coagulation system in patients with overt hypothyroidism (OH), to assess the effects of levothyroxine (LT4) on the coagulation parameters, and to determine whether subclinical hypothyroidism (SH) affects concentrations of coagulation markers and several biochemical parameters, thereby supporting early substitution. DESIGN: The study included 15 patients with SH (TSH levels 5-10 mU/l), 15 patients with OH and 15 euthyroid controls. METHODS: Blood urea nitrogen, creatinine, creatine phosphokinase, aspartate aminotransferase, lactate dehydrogenase, total-cholesterol, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol and triglyceride levels, and bleeding time, prothrombin time (PT), activated partial thromboplastin time (APTT), factor VIII activity, von Willebrand factor activity (vWF), platelet count and clotting time were evaluated just before and three months after the maintenance of euthyroidism with LT4 treatment. RESULTS: Factor VIII and vWF activities were lower in patients with SH than in controls (P < 0.01). Increased bleeding time, PT, APTT and clotting time and decreased factor VIII activity and vWF activity were observed in patients with OH when compared with controls. Bleeding time, PT, APTT and clotting time decreased and factor VIII activity, vWF and platelet count increased after LT4 in patients with OH. Increases in factor VIII activity and vWF (P < 0.01) were detected also in the SH group with treatment. CONCLUSIONS: OH is associated with significant abnormalities in clotting parameters which are reversed by LT4. In contrast, SH is associated with minor changes in factor VIII activity and vWF which are reversible by LT4. Serum lipids and other measured parameters are not improved by LT4 in patients with TSH < 10 mU/l and these data fail to demonstrate a need to treat such patients.     

凝血状况对社区获得性肺部感染患者病情影响的研究

目的：探讨凝血状况对社区获得性肺炎(CAP)患者病情评估的价值。方法选取2014年4月至2016年2月期间我院接诊的168例 CAP 患者为研究对象,归为观察组,再根据1∶1的配对比例选取同期来我院体检的168例健康成人作为对照组。并根据肺炎严重程度指数(PSI)将观察组患者分为中高风险组(n =63)和低风险组(n =105)。比较各组的凝血酶原时间(PT)、活化的部分凝血活酶时间(APTT)、凝血酶时间(TT)、纤维蛋白原(Fib)、血小板(PLT)、D-二聚体(DD)等指标,采用简单线性相关分析各凝血指标与肺炎严重程度指数(PSI)评分的相关性,采用受试者工作特征(ROC)曲线评价各凝血指标及 PSI 评分对 CAP 患者死亡的预测价值。结果共有15例(8.9%)患者因 CAP 或并发症死亡。观察组的 PT、APTT、Fib、PLT、DD 均显著高于对照组,差异有统计学意义(P <0.05)。中高风险组的血 PT、APTT、TT、DD 水平及 PT、DD 的异常率均显著高于低危组,差异有统计学意义(P <0.05)。简单线性相关分析结果表明 DD 与 PSI 评分呈显著正相关(r =0.508,P <0.01),而 PT、APTT、TT、Fib、PLT 等与 PSI 评分无显著相关性(r =0.143、0.106、0.129、0.085、0.098,P 值均>0.05)。ROC 曲线分析结果表明 PT、DD、PSI 评分在预测 CAP 的生存状况方面的 AUC 分别为0.552(95% CI 0.461~0.646,P >0.05)、0.916(95% CI 0.883~0.956,P <0.01)、0.889(95% CI 0.842~0.931,P <0.01)。结论 CAP 可以引起凝血功能的紊乱,DD 与其病情严重程度密切相关,可作为患者病情评估和预后预测的重要指标。     

新鲜冰冻血浆不同解冻方式的凝血试验分析

目的:探讨新鲜冰冻血浆(FFP)在电热恒温水浴箱和数控冷冻血浆干式解冻仪解冻后凝血因子检测指标的变化,保证临床输血的有效性和安全性。方法:将保存3个月的同一献血者分离的2份FFP分别用电热恒温水浴箱和数控冷冻血浆干式解冻仪解冻,测定其完全解冻时间、凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、凝血酶时间(TT)、纤维蛋白原(FIB),并进行统计学分析。结果:数控冷冻血浆干式解冻仪与电热恒温水浴箱在解冻时间、APTT测定上差异有统计学意义(P0.05);其他凝血因子指标PT、TT、FIB差异无统计学意义(P0.05)。结论:FFP用数控冷冻血浆干式解冻仪解冻优于电热恒温水浴箱,可以提高输血的安全性和有效性,值得推荐使用。     

Coagulation disorders and inhibitors of coagulation in children from Mansoura, Egypt

Disorders of coagulation in children often prove challenging to the medical care team. The aims of this study were to assess the spectrum and prevalence of coagulation disorders among children attending Mansoura University Children Hospital (MUCH), Mansoura, Egypt. A total of 105 pediatric patients were referred to MUCH. They were divided into two groups: congenital coagulation disorders (75 cases, age 45.36 +/- 48.59 months), and acquired coagulation disorders (30 cases, age 56.13 +/- 61.61 months). All patients were subjected to thorough history taking including the nature of bleeding, family, past history, mode of inheritance, and detailed physical findings. Hemostatic tests included: platelet count, bleeding time (BT), prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT). Specific tests in the congenital group include assay of coagulation factors according to each disorder, Von Willebrand factor assay, ristocetin aggregation test, APTT mixing study for detection of inhibitors in complicated hemophilia cases, F VIII C to VWAg ratio with cut off 0.7 for detection of carriers in some hemophilia A families. Congenital disorders constituted 71.4% of the studied cases vs. 28.6% for acquired disorders. Hemophilia A (42.85%), hemophilia B (14.28%) and liver diseases (14.28%) represented the majority of the studied cases. Mild and moderate cases of hemophilia A and B are more frequent than severe cases in both types. Male sex is more frequent than female in the congenital group (94.7 vs. 5.3%, P < 0.001). Direct correlation existed between factor level assay and severity of hemophilia (r = 0.73, P = 0.006). Three mothers and one sister were identified as carrier out of four families. Anti-clotting factors inhibitor was detected in 18.2% of patients with hemophilia A and in 9.1% with hemophilia B. In conclusion, our study found that hemophilias are the most prevalent congenital coagulation disorders among children. Attention must be given for detection of hemophilia carriers and inhibitors of clotting factors.     

Activated Partial Thromboplastin Time

An internationally standardized preparation and 10 commercial kits widely used to perform the activated partial thromboplastin time (APTT) were compared in 4 laboratories for the purpose of assessing their ability to detect mild deficiencies of factor VIII activity. The participating laboratories were asked to carry out with each APTT reagent quadruplicate readings of 3 coded lyophilized plasmas containing varying levels of factor VIII (109, 26 and 17 U/dl respectively). An analysis of variance of clotting times showed significant differences between reagents and laboratories. All the reagents detected the abnormality of the plasma containing 17 U/dl, whereas a number of failures were found when the plasma with 26 U/dl was tested. When analysis of variance was carried out on ratios of factor-VIII deficient to normal plasma clotting times, the results showed less difference between laboratories and reagents. Clotting times of plasma with normal factor VIII level (109 U/dl) usually fell within the normal range indicated by manufacturers of the commercial reagents.     

血栓弹力图在主要外科手术围手术期中的应用

影响围手术期凝血功能的因素具有多样性,目前检测凝血功能的方法包括凝血酶原时间(PT)、活化部分凝血酶原时间(APTT)、血小板(PLT)计数、纤维蛋白原(FIB)浓度等传统凝血检测项目和血栓弹力图(TEG),而传统的凝血检测只能监测凝血过程中的一部分,不能反映凝血的动态变化,无法准确判断凝血异常的原因。TEG可以快速、准确、全面、动态地监测血液凝固的全过程,合理地评估围手术期的凝血功能,为临床治疗提供理论依据。     

血小板参数和凝血指标与溶栓治疗关系的探讨

目的 动态观察急性脑梗死患者溶栓治疗过程中血小板参数及凝血指标的变化规律,探讨血小板参数和凝血指标与溶栓治疗的关系.方法 应用血细胞分析仪检测180例急性脑梗死患者（实验组）和180例健康体检者（对照组）的血小板计数（PLT）、血小板平均体积（MPV）和大血小板比率（P-LCR）,血凝分析仪检测凝血酶原时间（PT）、部分活化凝血活酶时间（APTT）、纤维蛋白原（Fg）及凝血酶时间（TT）,动态观察溶栓前及溶栓后1、2、4小时和48小时血小板参数和凝血指标的变化.结果 溶栓前脑梗死患者的MPV、P-LCR和Fg含量均高于对照组（P均＜0.05）,PLT、PT和APTT显著低于对照组（P均＜0.05）;溶栓治疗后,MPV、P-LCR和Fg含量显著下降,PLT、PT和APTT显著升高（P均＜0.05）.结论 溶栓治疗过程中,动态监测急性脑梗死患者的血小板参数（PLT、MPV和P-LCR）和凝血指标（PT、APTT、Fg）,可反映患者凝血功能的变化,对脑梗死患者的溶栓治疗具有一定的参考价值.     

Comparability of the results of PT-INR with local MNPT and APTTR with MNAPTT on different coagulation analyzers in China

The prothrombin time (PT), International normalized ratio (INR) and activated partial thromboplastin time (APTT) are the most used coagulation tests in China, where more than one type of automated coagulation analyzer is often used in the clinical laboratory. The PT-INR results of 109 samples were compared with local mean normal PT (MNPT) and APTT ratio (APTTR) with mean normal APTT (MNAPTT) on two different coagulation analyzers in the same laboratory. The two different coagulation analyzers showed no significant difference (P > 0.05) in PT and INR determination, but there was a significant difference (P < 0.01) for APTT. The INR with local MNPT and APTTR with MNAPTT, obtained with the ACL Futura and CA 510, showed much better agreement; 98.8% (82/83) of bias for INR with local MNPT was less than 15% compared with 90.4% (75/83) of bias for INR; and 100% of bias for APTTR (62/62) was less than 15% compared with only 6.5% (4/62) of bias for APTT. Meanwhile, there was no significant difference (P = 0.865) for APTTR with MNAPTT compared with APTT (P = 0.002) between the ACL Futura and CA 510. In conclusion, these analyzers showed very poor agreement for both the PT and APTT, but the calculation of ratios significantly improved agreement.