激活剂对检测活化部分凝血活酶时间的差异性研究

目的探讨不同激活剂作为活化部分凝血活酶时间(APTT)检测试剂时对APTT测定结果的影响。方法用鞣花酸和白陶土两种激活剂分别在LG-PABER-1型血凝分析仪和Sysmex CA-500全自动血凝分析仪上进行APTT检测,并在血浆中分别加入肝素钠和乏因子血浆进行APTT检测。运用t检验和方差分析对检测结果进行统计学分析。结果⑴在LG血凝仪上运用鞣花酸和白陶土作为不同激活剂,对37例临床标本进行APTT测定结果显示:白陶土作为激活剂测得的结果高于鞣花酸测得的结果(P0.05)。⑵同一批号的鞣花酸作为激活剂在Sysmex血凝仪和LG血凝仪上分别对40例临床标本进行APTT测定,结果显示:LG血凝仪上测得的结果高于Sysmex血凝仪测得的结果(P0.05)。⑶鞣花酸和白陶土作为不同激活剂对含有不同浓度肝素钠的血浆35例进行APTT测定结果显示:随着肝素钠浓度的增加,两种激活剂的APTT结果明显延长,与未加肝素钠组比较有显著差异(P0.05)。且鞣花酸组变化比白陶土组变化更明显。⑷运用鞣花酸和白陶土作为不同激活剂,对加入不同乏凝血因子的血浆后的血浆33例进行APTT测定显示:随着血浆中加入乏因子血浆的比例增多,两种激活剂的APTT结果延长也明显,与未加乏因子血浆的血浆的APTT比较有显著差异(P0.05)。且白陶土组变化比鞣花酸组更明显。结论不同激活剂APTT检测结果存在差异,且对肝素或乏因子血浆的敏感性存在差异;同一激活剂在不同仪器上APTT检测结果存在差异。建议不同的实验室应建立自己的参考范围。     

儿童止血发育过程中APTT动态变化及延长原因分析

目的:研究正常儿童活化部分凝血活酶时间(APTT)随年龄变化的趋势,探讨儿童APTT延长原因.方法:统计分析18例新生儿、49例婴儿、1 308例1～18岁儿童APTT情况,并以697例成人(同期行择期非感染小手术患者)作为对照组,并测定部分APTT延长儿童的血浆凝血因子Ⅷ、Ⅸ、Ⅺ、Ⅻ活性(FⅧ:C、FⅨ:C、FⅪ:C、FⅫ:C)和狼疮抗凝物(LAC),以探讨差异形成原因.结果:新生儿APTT最长,6～12个月婴儿APTT向成人水平接近,但与成人间差异仍有统计学意义(P=0.017);3岁后APTT又有延长趋势,9岁以后APTT又趋向缩短,至18岁较为接近成人水平,但与成人比较,差异仍有统计学意义(P=0.038).APTT延长的儿童FⅫ:C、FⅨ:C显著低于成人对照组[JL童FⅫ:C和FⅨ:C分别为43.86%(28.92%～61.08%)和(74.45±14.93)%;成人FⅫ:C和FⅨ:C分别为83.48%(47.24%～113.8%)和(99.71±17.26)%],差异有统计学意义(P＜0.001).在a=0.01水平,APTT与FⅫ:C和FⅨ:C呈负相关,与LAC筛选比率(IAC-SR)呈弱相关,相关系数(r)分别为-0.829、-0.695、0.401(P均＜0.01);APTT与FⅨ:C和FⅧ:C不相关.FⅫ:C降低与LAC-SR呈弱负相关(r0.01=-0.379,P=0.008).结论:儿童APTT随着年龄增长而呈动态变化;FⅫ:C和FⅨ:C低水平是儿童APTT延长的主要原因.     

Performance guidelines for the partial thromboplastin time test

Summary The partial thromboplastin time (PTT) test is widely used as a screening test for the detection of hemophilia. It is also used to monitor patients on heparin anticoagulation. These proposed guidelines for the performance of this test, including comparable reference ranges, precision and sensitivity requirements are felt to be reasonable and attainable. Whether further progress will occur depends upon a perceived need by laboratorians, instrument and reagent manufacturers and government regulators that standardization of the PTT is desirable. Presented at the ‘2nd International Symposium on Standardization and Quality Control of Coagulation Tests: Implications for the Clinical Laboratory’, Rome, September 28–29, 1989.     

Coagulation studies: prothrombin time, partial thromboplastin time, bleeding time

Three coagulation tests available in the emergency department are described in this article. Methods, results, and implications in the bleeding patient are reviewed.     

Prediction of recurrent venous thromboembolism by the activated partial thromboplastin time

BACKGROUND: Venous thromboembolism (VTE) is a multi-factorial disease. Extensive thrombophilia screening is costly and often inconclusive. Simple laboratory methods are required to predict the risk of recurrence. OBJECTIVE: To assess if measurement of activated partial thromboplastin time (APTT) allows stratification of patients with VTE into high- and low-risk categories with regard to recurrence. PATIENTS AND METHODS: We prospectively followed 918 patients with a first unprovoked VTE and studied the relationship between recurrence and an APTT after discontinuation of anticoagulation. APTT was expressed as a ratio of test to reference coagulation times. Study endpoint was symptomatic recurrent VTE. RESULTS: Venous thromboembolism recurred in 101 (11%) patients. Patients without recurrence had a greater APTT ratio than those with recurrence (0.97 +/- 0.09 vs. 0.93 +/- 0.09, P = 0.001). After 4 years, probability of recurrent VTE was 8.5% (95% CI: 5.5-11.5%) among patients with a ratio equal to or > 0.95 and 15.6% (95% CI: 11.4-19.9%) among patients with a lower ratio (P = 0.005). Compared with patients with an APTT ratio < 0.95, the relative risk (RR) of recurrence among patients with a ratio equal to or > 0.95 was 0.56 (95% CI: 0.38-0.84, P = 0.005) before and 0.58 (95% CI: 0.39-0.87, P = 0.009) after adjustment for sex, age, factor V Leiden, and factor II G20210A. CONCLUSIONS: Measurement of APTT allows stratification of patients with VTE into high- and low-risk categories with regard to recurrence.     

活化的部分凝血活酶时间异常结果的判定标准

目的　探讨仪器法测定活化的部分凝血活酶时间 (APTT)的参考范围和异常结果的判定标准。方法　用两种APTT试剂测定正常人、口服抗凝药病人、标准Ⅷ因子血浆及肝素钙血浆的APTT值。分析两种APTT试剂测定的结果间是否存在差异。结果　两种APTT试剂测定结果若以秒的形式报告有显著差异 ,若以APTT比值的形式报告则无显著差异。结论　各临床实验室应确定自己的参考值范围。检测结果以比值的形式报告 ,各实验室间的结果具有可比性。仪器法测定APTT应以病人结果比正常对照延长 7s以上为异常的判定标准。     

A lyophilized reagent for standardization of the activated partial thromboplastin time]

Native partial thromboplastin, prepared from cadaver brain thromboplastin (a reagent), is a cephalin analog used to detect disorders in the first phase of coagulation. It was lyophilized with the aim of its stabilization, potential commercial manufacture, and introduction into practical clinical laboratories. Native emulsion was distributed into 0.2 ml penicillin flasks and lyophilized for 18-20 hrs in IZ-9 (CSR) or similar equipment at the maximum temperature of the product 5 degrees C. Lyophilized reagent is a white or slightly cream-colored powder. It retains its activity for at least a year as evidenced by the activated partial thromboplastin time test. The range of activities within one lot is less if commercial lyophilized donor reference plasma is used in the test. The reagent is stored in a refrigerator at 4-8 degrees C.     

Prognostic value of the activated partial thromboplastin time after orthotopic liver transplantation

Summary In this prospective study, we evaluated the predictive value of activated partial thromboplastin time on day 8 post transplantation for event-free survival in patients who had had orthotopic liver transplants; both death and retransplantation within 6 months were the events considered. In a 4-year period, 109 patients had orthotopic liver transplants in our hospital, and 104 were eligible for the study since they survived and were not given new transplants within 8 days. The activated partial thromboplastin time was significantly longer in patients who survived event-free for less than 6 months than in those with longer event-free survivals. Kaplan-Meier curves showed that patients with normal activated partial thromboplastin times were nine times more likely to survive more than 6 months without events than patients with prolonged values. The positive predictive value of activated partial thromboplastin time for event-free survival was 88% and the negative predictive value was 54%, indicating that the test is useful for predicting patient outcome. We suggest that activated partial thromboplastin time be performed on day 8 post transplantation to predict the medium-term event-free survival.     

Correlation between activated clotting time and activated partial thromboplastin times

OBJECTIVE: To evaluate the correlation between clotting time tests and heparin concentration, the correlation between activated clotting time (ACT) and activated partial thromboplastin time (aPTT) results, and to compare the clinical decisions based on ACT results with those based on aPTT results. METHODS: Retrospective evaluation of a large database containing heparin concentrations, ACT results (1 device), and aPTT results (3 different instruments: 2 bedside, 1 laboratory-based). Correlations between heparin concentrations and clotting time tests and between ACT results and aPTT results were determined. Clinical decisions regarding heparin dosage adjustments based on ACT results were compared with those based on aPTT results. RESULTS: Correlations between clotting time tests and heparin concentrations were r = 0.72 for ACT and r = 0.74-0.86 for the aPTT instruments. The laboratory-based aPTT had the highest correlation to heparin concentrations. The correlation between ACT and aPTT results ranged from r = 0.64-0.67. Heparin dosage adjustment decisions based on ACT results agreed with decisions based on aPTT results 59-63% of the time. CONCLUSIONS: The laboratory-based aPTT has a stronger correlation to heparin concentration than the bedside-based aPTT and ACT. The correlation between ACT and aPTT was similar among 3 different aPTT instruments. Decisions to adjust heparin therapy based on ACT results differed from decisions based on aPTT results more than one-third of the time.     

Comparative analysis on characteristics of two activated partial thromboplastin time reagents

BackgroundFor the lack of standardized activated partial thromboplastin time (APTT), it has been pointed out that there are differences in values among several reagents. Recently, we have performed a parallel measurement on two reagents, Thrombocheck APTT‐SLA and Coagpia APTT‐n, and resulted with some dissociated samples. The purpose of this study is to clarify the possible factors related to ΔAPTT, the difference in measured values between the two reagents.Materials and MethodsIn order to clarify the factors related to ΔAPTT, multiple regression analysis was performed on 8324 samples, using clinical laboratory data of all test items requested simultaneously with APTT. To confirm the items extracted from the multiple regression analysis, the target substance was spiked to pooled plasma and measured with two APTT reagents. Additionally, by spiking phospholipids, the effect on APTT measurement system was assessed.ResultMultiple regression analysis detected albumin–globulin ratio (AGR), C‐reactive protein (CRP), hematocrit, and prothrombin time as factors related to ΔAPTT (p < 0.001). Results revealed no significant differences when albumin was added to change the AGR. Whereas with the addition of CRP, prolongation of APTT was observed in Coagpia APTT‐n compared to Thrombocheck APTT‐SLA (p < 0.001). This prolongation was canceled by the addition of phospholipids, suggesting the interaction of CRP with phospholipids leads to the pseudo‐prolongation.ConclusionIt is considered that the pseudo‐prolongation of APTT is triggered by the interaction of CRP on the phospholipid in Coagpia APTT‐n, which contributed to the APTT dissociation.