凝血活酶参考品国际敏感度指数的标定

目的 标记出凝血活酶参考品（ＷＲＰ），对国内凝血活酶产品国际敏感度指数（ＩＳＩ）的标定提供依据。方法 以凝血活酶国际参考品为标准（ＩＲＰ）按照世界卫生组织（ＷＨＯ）推荐的凝血活酶国际参考样品的使用方法进行了测定，计算了被定凝血活酶参考品的ＩＳＩ值和标定ＩＳＩ值的变异系数（ＧＶ），结果 标出的凝血活酶参考品的ＩＳＩ值为１．３５，标定ＩＳＩ值的ＣＶ为４．３％，符合ＷＨＯ的要求（ＣＶ≤５％），结论 用Ｉ     

自动凝血仪凝血活酶国际敏感指数的标定

全自动凝血仪对凝血活酶ＩＳＩ的影响。按ＷＨＯ推荐的方法将凝血仪检测ＰＴ时的凝血活酶视为未知ＩＳＩ值的凝血活酶，用已知ＩＳＩ的凝血活酶对其进行标定。比较两仪器ＩＳＩ标定前后检测听ＩＮＲ结果，ＣＡ＿５３０及ＣＡ－１５００凝血仪对ＩＳＩ标为１．２７的凝血活酶标定值分别为１．１８和１．２１；比较两仪器珠ｌｏｇＰＴＲ值有显著性差异；ＩＳＩ一前两仪器测定的ＩＮＲ结果有较大的变异（ＣＶ值为１３．４％），ＩＳＩ标     

凝血活酶参考制品的标定与推广应用

目前国际上已有公认的凝血活酶参考制品,但国内尚无统一的参考制品供应使用,卫生部临床检验中心于１９９６年向世界卫生组织（ＷＨＯ）申请获得了凝血活酶的国际参考制品,以该参考品为标准,标定了国家凝血活酶参考制品,国际敏感度指数为１．７８,变异系数为５％,符合凝血活酶参考品的标准,并已在国内推广应用,为我国凝血活酶测定的标准化提供了必备的条件 。     

猪肺凝血活酶的标定及初步临床应用

目的：标定自制猪肺凝血活酶并应用于病人测定。方法：根据ＷＨＯ参比方法,用已知国际敏感指数（ＩＳＩ）的凝血活酶标定自制猪肺凝血活酶。用进口试剂的自制品测定６０例口服华法令抗凝治疗病人和４０例肝病患者的ＰＴ,求得ＰＴＲ和ＩＮＲ并进行比较。     

标准曲线法测定凝血酶原时间国际标准化比值

目的利用ＩＮＲ质控血浆，建立一种简便、易于临床实验室开展的凝血酶原时间国际标准化检测方法，并对其进行初步评价。方法用ＷＨＯ推荐的手工检测方法标定ＩＮＲ质控血浆ＩＮＲ值作为ＩＮＲ参比血浆，自动化凝血仪检测其ＰＴ凝固时间，建立ＩＮＲ标准曲线；利用标准曲线测定待检血浆的ＩＮＲ值。比较两种常用凝血活酶试剂并分别用ＩＮＲ公式计算法和本方法检测ＩＮＲ参比血浆的ＩＮＲ值，评价其线性、重复性以及不同试剂之间的重复性。用ＷＨＯ推荐的ＩＮＲ公式计算方法，分别用手工和仪器检测 ４７例临床标本 ＩＮＲ值，并与本方法进行比较。结果血浆 ＩＮＲ值与ＰＴ凝固时间有很好的线性关系（ｒ＝ ０．９９５）；单种试剂本方法检测ＩＮＲ参比血浆ＩＮＲ值，重复性良好（ＣＶ％＜２％）；两种不同试剂测定血浆ＩＮＲ值，结果显示本方法的重复性优于ＩＮＲ公式计算法；本方法测定结果与 ＷＨＯ推荐的手工法测定结果有很好的相关（ｒ＝０．９９），并比 ＩＮＲ 公式计算法检测的 ＩＮＲ值更接近手工检测值（ｔ检验Ｐ值：０．００３对０．０７３）。结论本方法能检测抗凝治疗患者血浆的ＩＮＲ值。用自动化仪器检测ＰＴ时，本方法较ＩＮＲ公式计算法简便易行，干扰因素少，其检测结果可能更接近血浆Ｉ     

凝血质的标定及凝血酶原时间标准化的临床应用

本文根据ＷＨＯ参比方法用已知国际敏感度指数的凝血质对两种未知ＩＳＩ的凝血质进行了标定，并以标准形式报告ＰＴ结果。     

仪器对凝血酶原时间国际标准化比值的影响及校正

为了评价血凝仪对国际标准化比值的影响。模拟ＷＨＯ标定凝血质的参比方法，用一种已 知国际敏感指标的凝血质对两种血凝仪的特异性ＩＳＩ进行标定，并以ＩＮＲ形式报告ＰＴ结果。     

凝血活酶试剂敏感性的观察

探讨国产凝血活酶敏感性不高的原因。方法：１．用进口标有ＩＳＩ的凝血活酶，定值参比血浆，标定国产凝血活酶的ＩＳＩ。２．以此凝血活酶检测参比血浆及患者血浆的ＰＴ。３．测定进口及国产凝血活酶的ｐＨ，磷脂含量。结果：凝血活酶Ａ，Ｂ，ＩＳＩ为１．３９，１．８５。ＰＴ正常参考值１１－１３ｓ。但测定异常参比血浆Ｌｅｖｅｌ２，３及患者ＰＴ，ＰＴＰ均低于参比血浆测定的结果。     

混合静脉血氧饱和度与心脏指数的关系

对３０例心脏换瓣术病人术后同时监测混合静脉血氧饱和度（ＳＶＯ２）与心脏指数（ＣＩ），二者呈非线性相关，相关系数０６６，当校正了个体之间氧耗（ＶＯ２）和血红蛋白值（Ｈｂ）的差异后，其相关系数为０９４。运用直线回归法分析个体资料，Ａ、Ｂ组病人平均ＣＩ和ＳＶＯ２分别为２４５Ｌ·ｍｉｎ－１·ｍ－２和６１％，３３０Ｌ·ｍｉｎ－１·ｍ－２和７３４％，其平均斜率和相关系数分别是１８２和０８６，０８８和０２０。故认为一组病人ＳＶＯ２与ＣＩ关系的非线性相关系数高低取决于其ＶＯ２和Ｈｂ值的均一性，ＳＶＯ２作为某一病人监测ＣＩ变化的作用取决于ＳＶＯ２和ＣＩ的状态。     

组织凝血活酶的标化在PT测定中的应用

我们应用自制的组织凝血活酶制剂对凝血活酶的ＩＳＩ值标定及ＰＴ测定的标准化做了一些探索。1　试剂抗凝剂:129ｍｍｏｌ/Ｌ枸橼酸钠溶液(ＢＤ公司);ＣａＣｌ2溶液:25ｍｍｏｌ/Ｌ(自配,化学纯);丙酮:化学纯;标准凝血活酶:ＩＬ公司,批号:ＮＯ379471;自制兔脑干粉。2　方法与结果21　标本　校正血浆(Ｃａｌｉｂｒａｔｉｏｎｐｌａｓｍａ):ＩＬ公司,批号:ＮＯ1269707。正常血浆:枸橼酸钠1:9抗凝的正常自愿者血浆在低温(-70。Ｃ)保存。口服抗凝药患者血浆:心脏换瓣手术后,口服华法令稳定三周后的患者血,处理保存同前。22　组织凝血活酶的制备　…     

Comparison of pituitary and recombinant human thyroid-stimulating hormone (rhTSH) in a multicenter collaborative study: establishment of the first World Health Organization reference reagent for rhTSH

BACKGROUND: The increasing use of recombinant-DNA-derived materials in therapy and diagnosis poses a new challenge for biological standardization, that of developing reference preparations appropriate for both the native and recombinant products. Here we report the results of an international collaborative study that was carried out under the auspices of WHO to assess the suitability of a preparation of recombinant thyroid-stimulating hormone (rTSH; 94/674) to serve as a potential standard for the calibration of diagnostic immunoassays compared with the International Reference Preparation (IRP) for human TSH (80/558). METHODS: Coded samples were provided to the 33 laboratories in the study, and participants were asked to perform TSH assays currently in use in their laboratories. Twenty-eight laboratories contributed 93 immunoassays in 41 different method-laboratory combinations, and an additional 5 laboratories contributed bioassay data. All data were analyzed centrally at the National Institute for Biological Standards and Control. RESULTS: The results obtained in different laboratories and with different assay systems revealed significant variability between estimates of rTSH relative to the IRP. These ranged from 5. 51 mIU (95% limits, 3.95-7.67 mIU) per ampoule by RIA to 7.15 mIU (95% limits, 6.7-7.63 mIU) per ampoule by immunofluorometric assay. However, the results showed that the assignment of a value of 6.70 mIU per ampoule of 94/674 would give reasonable continuity with the IRP in many assay systems. CONCLUSIONS: The preparation was established as the First WHO Reference Reagent for TSH, human, recombinant, to provide a means of validating assay performance and to maintain continuity with the IRP without compromising clinical data.     

International collaborative study for the calibration of proposed International Standards for thromboplastin,rabbit, plain,and for thromboplastin,recombinant, human,plain

Essentials

• Two candidate International Standards for thromboplastin (coded RBT/16 and rTF/16) are proposed.
• International Sensitivity Index (ISI) of proposed standards was assessed in a 20‐centre study.
• The mean ISI for RBT/16 was 1.21 with a between‐centre coefficient of variation of 4.6%.
• The mean ISI for rTF/16 was 1.11 with a between‐centre coefficient of variation of 5.7%.

Summary

Background

The availability of International Standards for thromboplastin is essential for the calibration of routine reagents and hence the calculation of the International Normalized Ratio (INR). Stocks of the current Fourth International Standards are running low. Candidate replacement materials have been prepared. This article describes the calibration of the proposed Fifth International Standards for thromboplastin, rabbit, plain (coded RBT/16) and for thromboplastin, recombinant, human, plain (coded rTF/16).

Methods

An international collaborative study was carried out for the assignment of International Sensitivity Indexes (ISIs) to the candidate materials, according to the World Health Organization (WHO) guidelines for thromboplastins and plasma used to control oral anticoagulant therapy with vitamin K antagonists.

Results

Results were obtained from 20 laboratories. In several cases, deviations from the ISI calibration model were observed, but the average INR deviation attributabled to the model was not greater than 10%. Only valid ISI assessments were used to calculate the mean ISI for each candidate. The mean ISI for RBT/16 was 1.21 (between‐laboratory coefficient of variation [CV]: 4.6%), and the mean ISI for rTF/16 was 1.11 (between‐laboratory CV: 5.7%).

Conclusions

The between‐laboratory variation of the ISI for candidate material RBT/16 was similar to that of the Fourth International Standard (RBT/05), and the between‐laboratory variation of the ISI for candidate material rTF/16 was slightly higher than that of the Fourth International Standard (rTF/09). The candidate materials have been accepted by WHO as the Fifth International Standards for thromboplastin, rabbit plain, and thromboplastin, recombinant, human, plain.     

The prothrombin time/international normalized ratio (PT/INR) Line: derivation of local INR with commercial thromboplastins and coagulometers – two independent studies

Summary. Background: The WHO scheme for prothrombin time (PT) standardization has been limited in application, because of its difficulties in implementation, particularly the need for mandatory manual PT testing and for local provision of thromboplastin international reference preparations (IRP). Methods: The value of a new simpler procedure to derive international normalized ratio (INR), the PT/INR Line, based on only five European Concerted Action on Anticoagulation (ECAA) calibrant plasmas certified by experienced centres has been assessed in two independent exercises using a range of commercial thromboplastins and coagulometers. INRs were compared with manual certified values with thromboplastin IRP from expert centres and in the second study also with INRs from local ISI calibrations. Results: In the first study with the PT/INR Line, 8.7% deviation from certified INRs was reduced to 1.1% with human reagents, and from 7.0% to 2.6% with rabbit reagents. In the second study, deviation was reduced from 11.2% to 0.4% with human reagents by both local ISI calibration and the PT/INR Line. With rabbit reagents, 10.4% deviation was reduced to 1.1% with both procedures; 4.9% deviation was reduced to 0.5% with bovine/combined reagents with local ISI calibrations and to 2.9% with the PT/INR Line. Mean INR dispersion was reduced with all thromboplastins and automated systems using the PT/INR Line. Conclusions: The procedure using the PT/INR Line provides reliable INR derivation without the need for WHO ISI calibration across the range of locally used commercial thromboplastins and automated PT systems included in two independent international studies.     

International normalized ratio in the prothrombin test: clinical significance and use

The safety and efficiency of therapy by peroral anticoagulants (PA) depend on a laboratory monitoring based on the prothrombin test (PT). The test is distinguished through its variability conditioned by different means of results' presentation as well as through the sensitivity of thromboplastin and a type of a device used in coagulation detection. WHO recommended, 1983, to standardize the thromboplastin preparations through adjusting their sensitivity (the so-called International Sensitivity Index--ISI) to blood coagulation defects induced by PA versus the primary international reference thromboplastin. Thromboplastin ISI as well as the mean normal prothrombin time (MNPT) of blood plasma are used to calculate the international normalized ratio (INR). The presentation of PT results as INR is justified exclusively for the PA-therapy stabilized patients. The INR system makes it possible to optimize the PA therapy only if the laboratory expert and clinician can clearly understand the PT standardization essence and observe the key WHO recommendations, i.e. definition of a coagulometer-specific ISI by manufacturing companies, estimation of MNPT by laboratories and use of the correct anticoagulant concentration.     

Determination of thromboplastin time with a new standardized thromboplastin from human placenta: results of a cooperative study

In five centres a new sensitive standardized thromboplastin from human placenta (Thromborel S) for determination of prothrombin time (PT) was evaluated on plasmas from healthy subjects, from patients on oral anticoagulant therapy and from patients with different diseases, especially of the liver. The standardization of the human placenta thromboplastin (HPT) for prothrombin time determination was performed by comparison with a lot of the Reference Preparation British Comparative Thromboplastin (BCT). The obtained International Sensitivity Index (ISI) for 14 differents lots of the new thromboplastin varied between 1.04 and 1.29 (mean value: 1.16). The reagent is highly sensitive to the factors of the extrinsic coagulation pathway and is not affected by heparin at least up to 0.6 IU/ml. From the comparison with the British Comparative Thromboplastin lot No. 235, a therapeutical range for the stable phase of the oral anticoagulation of 2.4-4.0 prothrombin ratio or 15-27% of normal, respectively, was obtained. Comparison of prothrombin time determination using the Human Placental Thromboplastin and the British Comparative Thromboplastin lot No. 235 in 330 patients on oral anticoagulation showed good correlations either in "percent normal" or in prothrombin ratio.     

Interpretations of five monoclonal immunoassays of lutropin and follitropin: effects of normalization with WHO standard

Five mono(oligo)clonal immunometric assays for lutropin (LH) and follitropin (FSH)--bioMérieux, IRE-Medgenix, Serono Diagnostics, Diagnostics Products Corp. (DPC), and LKB--were evaluated in comparison with two polyclonal RIAs (DPC and Amersham). Detection limits varied from 0.04 to 0.32 int. unit/L and 0.06 to 0.86 int. unit/L for LH and FSH, respectively. Intra- and interassay precision (CV) at three concentrations varied from 2.0% to 29.8%, showing that not all kits tested gave acceptable results, especially for LH. Linearity and parallelism were acceptable, except for the DPC FSH kit and the bioMérieux LH kit. High-dose "hook" effects were seen in some kits at LH concentrations of 250 int. units/L, but not in the FSH kits up to concentrations of 350 int. units/L. Reagents in some kits cross-reacted with choriogonadotropin. The clinical validity of the assays was tested in 25 pre- and 25 postmenopausal healthy women and in 66 patients with polycystic ovary disease. In contrast to FSH, LH values varied significantly not only between polyclonal and monoclonal assays but also between the various monoclonal assays, despite the fact that all manufacturers state that their kits are calibrated on the same standards: WHO International Reference Preparation (IRP) 68/40 for LH and 78/549 for FSH. We normalized the results by using new WHO standards: IRP 80/552 for LH and IRP 83/575 for FSH. This decreased significantly the between-kit differences in LH results for individuals. The much-used LH/FSH ratio greater than 3 for diagnosing patients with polycystic ovary disease is not valid when monoclonal assays are used, and is kit-dependent. However, using the normalized results yields a "new" LH/FSH ratio, which is kit-independent and differs significantly between patients and healthy subjects.     

Use of lyophilized calibrant plasmas for simplified international normalized ratio determination with a human tissue factor thromboplastin reagent derived from cultured human cells

BACKGROUND: For monitoring of treatment with oral anticoagulants, the clotting time obtained in the prothrombin time (PT) test is transformed to the International Normalized Ratio (INR) with use of a system-specific International Sensitivity Index (ISI). The calibrant plasma procedure (CPP) is an alternative approach to INR calculation based on the use of a set of lyophilized plasmas with assigned INRs. METHODS: With the CPP, a linear relationship is established between log(PT) and log(INR), using orthogonal regression. CPP was validated for Simplastin HTF, a new human tissue factor reagent derived from cultured human cells. CPP precision was assessed as the CV of the slope of the regression line. The accuracy of the CPP was determined by comparing the INR obtained with the CPP with that obtained with the established ISI-based reference method. INRs of the calibrants were assigned by different routes: by manufacturer (consensus labeling) or by use of Simplastin HTF or International Reference Preparations (IRPs; rTF/95 or RBT/90). RESULTS: The mean CV of the CPP regression slope ranged from 1.0% (Simplastin HTF reagent-specific INR) to 2.4% (INR assigned with rTF/95). INRs calculated with the CPP were similar to those obtained with the reference method, but when the routes for assigning INRs to the calibrant plasmas were compared, the mean difference in INR between CPP and the reference method was smaller with Simplastin HTF reagent-specific values. In several (but not all) cases, this difference was significant (P <0.05, t-test). CONCLUSION: CPP can be used for local INR determination, but better precision and accuracy are obtained with reagent-specific INRs compared with INR assignment by consensus labeling or IRP.     

International collaborative study for the calibration of a proposed international standard for thromboplastin, rabbit, plain

BACKGROUND: A preparation of rabbit brain thromboplastin, provisionally coded 04/162, is proposed as a candidate for the World Health Organization (WHO) International Standard (IS) for thromboplastin (rabbit, plain), meant to replace the IS coded RBT/90 (rabbit, plain), stocks of which are now exhausted. RESULTS: The preparation was calibrated in an international collaborative study involving 21 laboratories from 13 countries and the calibration was performed against the existing WHO-IS (i.e. rTF/95 and OBT/79) and other Certified Reference Materials from the Institute for Reference Materials and Measurements of the European Commission (i.e. CRM149 S) and from the European Action on Anticoagulation (i.e. EUTHR-01). An additional candidate rabbit brain thromboplastin coded as 04/106 was also included in the study. On the basis of predefined criteria (the within- and between-laboratory precision of the calibration and the conformity to the calibration model), 04/162 was the preferred candidate. CONCLUSIONS: The assigned International Sensitivity Index value was 1.15 and the inter-laboratory SD and coefficient of variation were 0.057% and 4.9%, respectively.     

Multicenter evaluation of new enzyme-linked immunoassays of follitropin and lutropin in serum or plasma

Results from a multicenter evaluation of two new enzyme-linked immunosorbent assays [Enzymun-Test for follitropin (FSH) and lutropin (LH)] are presented and compared with results from 11 other commercial immunoassays, radioactive as well as nonradioactive. Enzymun-Test FSH and LH assays are suitable for automated systems and manual applications. The tests were reproducible (CV less than 5%), highly specific, and sensitive enough (less than 0.5 int. unit/L) to measure the hormones directly in almost all patients' samples, except for LH measurements in prepubertal children. We did not find interference by heterophilic antibodies or other factors. A comparison of assays for FSH found very good agreement among all modern two-site assays; competitive immunoassays almost invariably yielded systematically lower results for FSH, probably because of the heterogeneity of the International Reference Preparation (2nd IRP FSH, 78/549). For LH also we found good agreement, with no systematic differences among the various reagents. Guidelines for reference values with the new reagents are given.     

Properties of recombinant human thromboplastin that determine the International Sensitivity Index (ISI)

Prothrombin Time (PT) clotting tests are widely used to monitor oral anticoagulation therapy and to screen for clotting factor deficiencies. The active ingredient in PT reagents (thromboplastins) is tissue factor, the integral membrane protein that triggers the clotting cascade through the extrinsic pathway. Several years ago, a system for calibrating and using thromboplastin reagents, known as the International Sensitivity Index (ISI) and the International Normalized Ratio (INR), was developed to standardize monitoring of oral anticoagulant therapy. The ISI/INR method, while revolutionizing the monitoring of coumarin therapy, has been criticized for a number of perceived shortcomings. We have undertaken a series of studies aimed at achieving a detailed understanding of which parameters influence the ISI values of thromboplastin reagents, with an ultimate goal of creating 'designer thromboplastins' whose sensitivities to the various clotting factors can be individually tailored. In this study, we demonstrate that ISI values of thromboplastin reagents based on relipidated, recombinant human tissue factor can be controlled by a combination of changes in the phospholipid content (in particular, the levels of phosphatidylserine and phosphatidylethanolamine) and ionic strength. The sensitivity of a given thromboplastin reagent can be increased (i.e. its ISI value decreased) by decreasing the content of phosphatidylserine and/or increasing the ionic strength. The molar ratio of phospholipid to tissue factor, on the other hand, had essentially no impact on ISI value.