浅析国际标准化比值与纤维蛋白原测定的实验室校准

随着人们饮食结构和生活方式的改变,心血管和血栓性疾病的发病率和病死率呈逐年增高的趋势,血栓栓塞作为多种系统疾病的并发症也成为临床医学的研究重点.近年来,止血血栓学检验在出血性疾病的诊断、术前筛查和抗凝治疗检测中得到了广泛应用,自动化凝血仪的普及大大提高了检测效率,使检测结果的精密度和准确度达到了前所未有的水平.配合凝血诊断试剂国家行业标准的推出,本文试对当前临床实践中的误区加以辨析.     

浅析国际标准化比值与纤维蛋白原测定的实验室校准

随着人们饮食结构和生活方式的改变,心血管和血栓性疾病的发病率和病死率呈逐年增高的趋势,血栓栓塞作为多种系统疾病的并发症也成为临床医学的研究重点.近年来,止血血栓学检验在出血性疾病的诊断、术前筛查和抗凝治疗检测中得到了广泛应用,自动化凝血仪的普及大大提高了检测效率,使检测结果的精密度和准确度达到了前所未有的水平.配合凝血诊断试剂国家行业标准的推出,本文试对当前临床实践中的误区加以辨析.     

血浆纤维蛋白原测定的进展

血浆纤维蛋白原是临床上常用的测定项目,它与出凝血性疾病、血栓病、缺血性心脑血管病等有关。本文综述了纤维蛋白原水平、亚组份、纤维蛋白单体聚集功能和基因多态性的测定方法以及各自的临床应用进展。     

血浆纤维蛋白原水平与纤维蛋白单体聚合功能的测定

目的 :建立广州地区健康成人血浆纤维蛋白水平及纤维蛋白原单体聚合功能的正常参考值。方法 :用蕲蛇酶 (Acutulase)水解纤维蛋白 ,用计算机自动检测系统测定。结果 :①纤维蛋白单体聚合反应速率 (FMPV)为 0 498± 0 1 1 0 ;②最大吸光度 (Amax)为 0 2 50± 0 0 5;③纤维蛋白原的浓度 (S)为 2 80±0 65( g/L) ;④FMPV/Amax比值为 1 992± 0 1 80 ;⑤反应延滞时间 (DT)为 2 5± 5(s)。结论 :计算机自动检测系统操作简单快捷 ,测出的纤维蛋白原浓度与传统改良的Clauss法相比 ,无显著性差异。FMPV/Amax比值稳定 ,表明正常人的纤维蛋白单体聚合能力与纤维蛋白的量成正相关。     

纤维蛋白原测定系统的探讨

目的探讨纤维蛋白原(FIB)冯*克劳斯法(von Clauss)测定仪器、试剂、标准曲线的配套问题,为上海市地区性血液凝固质量管理工作提供依据.方法使用仪器-试剂-标准曲线配套和非配套的方法对新鲜血浆和不同品牌质控血浆的FIB含量进行测定.结果使用仪器-试剂-标准曲线配套组合测定新鲜血浆和配套质控血浆的FIB含量结果良好.在仪器-试剂-标准曲线非配套组合时,测定新鲜血浆和质控血浆的FIB含量结果有差异.结论仪器间的FIB标准曲线不能混用,仪器-试剂应配套使用.应重视基质效应问题,FIB应根据仪器、试剂、方法进行分组统计.     

纤维蛋白原测定系统的探讨

目的　探讨纤维蛋白原 (FIB)冯·克劳斯法 (vonClauss)测定仪器、试剂、标准曲线的配套问题 ,为上海市地区性血液凝固质量管理工作提供依据。方法　使用仪器 试剂 标准曲线配套和非配套的方法对新鲜血浆和不同品牌质控血浆的FIB含量进行测定。结果　使用仪器 试剂 标准曲线配套组合测定新鲜血浆和配套质控血浆的FIB含量结果良好。在仪器 试剂 标准曲线非配套组合时 ,测定新鲜血浆和质控血浆的FIB含量结果有差异。结论　仪器间的FIB标准曲线不能混用 ,仪器 试剂应配套使用。应重视基质效应问题 ,FIB应根据仪器、试剂、方法进行分组统计     

血浆纤维蛋白原测定的进展

血浆纤维蛋白原是临床上常用的测定项目 ,它与出凝血性疾病、血栓病、缺血性心脑血管病等有关。本文综述了纤维蛋白原水平、亚组份、纤维蛋白单体聚集功能和基因多态性的测定方法以及各自的临床应用进展。     

硫酸铵比浊法测定血浆纤维蛋白原

本文经反复试验，筛选出的（ＮＨ４）２ＳＯ４１８０ｇ／Ｌ溶液与血浆中纤维蛋白原形成均匀浊度，与含量成正比。在试验中，取血浆０．２ｍｌ，加试剂４ｍｌ，混合后静置室温５ｍｉｍ，取波长５２０ｎｍ光电比浊，得出的Ａ值查曲线或含量检索表即获结果。本法操作简便，且与双缩脉显色法比较２０例，结果相关显著（ｒ＝０．８０）。     

Effect of lepirudin on the international normalized ratio

BACKGROUND: Many patients receiving direct thrombin inhibitor (DTI) therapy require transition to warfarin. This transition may be complicated by DTI-induced elevations in the international normalized ratio (INR). While the effect of argatroban on the INR has been characterized, data assessing the effect of lepirudin on the INR are limited. OBJECTIVE: To evaluate the effect of lepirudin on the INR. METHODS: Patients receiving lepirudin therapy between January 2000 and May 2001 were identified using the pharmacy database, and a retrospective chart review was conducted. Patients were included for analysis if they had paired activated partial thromboplastin time (aPTT) and INR data while receiving lepirudin monotherapy. RESULTS: Fifty-three paired aPTT and INR data points from 8 patients receiving lepirudin monotherapy were collected. The Organon MDA 180 instrument was used for aPTT and prothrombin time (PT) determination. Organon MDA Platelin L reagent was used for the aPTT and Organon Simplastin L reagent was used for the PT. The international sensitivity index (ISI) of the Simplastin L thromboplastin was 2.0. The mean +/- SD lepirudin dose was 0.05 +/- 0.04 mg/kg/h. Linear regression was used to identify the INRs that correspond to a therapeutic aPTT value of 45-75 seconds (1.5-2.5 times mean laboratory normal of 30 sec). The correlation between aPTT and INR was 0.77. An aPTT of 45-75 seconds with lepirudin correlated to an INR of 1.6-3.2. CONCLUSIONS: Based on laboratory results, when using a thromboplastin with an ISI of 2, lepirudin appears to elevate the INR in the absence of warfarin.     

Effect of stress on international normalized ratio during warfarin therapy

OBJECTIVE: To discuss the effect of stress on the international normalized ratio (INR) when patients are taking warfarin. CASE SUMMARY: Two patients at a pharmacist-managed anticoagulation clinic who were stable with anticoagulation developed elevated INR values after a stressful event occurred. All other factors known to elevate the INR were unchanged; furthermore, the INR values returned to the prior level of control after resolution of the stressful events. DISCUSSION: Management of anticoagulation with warfarin requires the knowledge of factors that may alter an INR. Many of these factors, such as dietary changes, illnesses, drug interactions, patient compliance, and physical activity, have been described. In spite of this understanding, many patients continue to experience variability in their INR values, suggesting there are other factors that can alter the INR that have not been fully described. The cases presented here demonstrate that stressful events, physical or psychological, can elevate the INR. The mechanism for this occurrence is unknown, but may be related to decreased metabolism of warfarin during stress. CONCLUSIONS: When an unexplained INR value exists, a stressor should be evaluated as a potential cause.     

Clinical utilization of the international normalized ratio (INR)

The prothrombin time (PT) is one of the most important laboratory tests to determine the functionality of the blood coagulation system. It is used in patient care to diagnose diseases of coagulation, assess the risk of bleeding in patients undergoing operative procedures, monitor patients being treated with oral anticoagulant (coumadin) therapy, and evaluate liver function. The PT is performed by measuring the clotting time of platelet-poor plasma after the addition of calcium and thromboplastin, a combination of tissue factor and phospholipid. Intra- and interlaboratory variation in the PT was a significant problem for clinical laboratories in the past, when crude extracts of rabbit brain or human placenta were the only source of thromboplastin. The international normalized ratio (INR), developed by the World Health Organization in the early 1980s, is designed to eliminate problems in oral anticoagulant therapy caused by variability in the sensitivity of different commercial sources and different lots of thromboplastin to blood coagulation factor VII. The INR is used worldwide by most laboratories performing oral anticoagulation monitoring, and is routinely incorporated into dosage planning for patients receiving warfarin. Although the recent availability of sensitive PT reagents prepared from recombinant human tissue factor (rHTF) and synthetic phospholipids eliminated many of the earlier problems associated with the use of crude thromboplastin preparations, local instrument variability in the INR still remains a problem. Presently, the use of plasma calibrants seems the best solution to this problem. Standardizing the point-of-care instruments for INR monitoring is another dilemma faced by the industry. Ultimately, new generations of anticoagulant drugs may eliminate the need for laboratory monitoring of anticoagulant therapy.