Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Int J Lab Hematol. 2021 Jul;43 Suppl 1:96-102. doi: 10.1111/ijlh.13564.
Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition resulting from pathogenic antibodies to complexes of heparin and platelet factor 4 (PF4). The diagnosis of HIT can be challenging due to the widespread use of heparin and the frequency of thrombocytopenia in hospitalized patients. Laboratory testing for HIT typically includes an immunoassay to detect antibodies to PF4-heparin and a functional assay. Current HIT diagnostic algorithms recommend using the 4Ts score to determine the need for HIT laboratory testing. Automated calculation of HIT clinical prediction scores in the electronic health record may improve the identification of patients who should undergo HIT testing. Another challenge in the management of patients with suspected HIT is the turnaround time of the laboratory testing needed to confirm the diagnosis. Due to the high daily thrombotic risk of HIT, clinicians must treat patients with intermediate to high pretest likelihood of HIT empirically while awaiting the test results. Treatment for HIT often involves alternative anticoagulants that lack reversal agents, which may increase bleeding risk, prolong hospital stays, and increase costs for patients suspected of having HIT. Rapid immunoassays hold promise to improve the speed of HIT diagnosis. These assays must retain a very high sensitivity for this "can't miss" diagnosis, yet have sufficient specificity to be of diagnostic value. A Bayesian approach has been proposed using two rapid immunoassays in succession, which decreased analytic turnaround time to 60 minutes. Such an approach has the potential to be a much-needed clinical advance in improving accuracy and speed in the diagnosis of HIT.
肝素诱导的血小板减少症 (HIT) 是一种由肝素和血小板因子 4 (PF4) 复合物的致病性抗体引起的血栓形成状态。由于肝素的广泛使用和住院患者血小板减少症的频率，HIT 的诊断具有挑战性。HIT 的实验室检测通常包括检测 PF4-肝素抗体的免疫测定和功能测定。当前的 HIT 诊断算法建议使用 4Ts 评分来确定是否需要进行 HIT 实验室检测。在电子健康记录中自动计算 HIT 临床预测评分可能有助于识别需要进行 HIT 检测的患者。在管理疑似 HIT 患者时的另一个挑战是，确认诊断所需的实验室检测的周转时间。由于 HIT 的每日血栓形成风险很高，临床医生必须在等待检测结果的同时，根据中间至高的预检测 HIT 可能性对患者进行经验性治疗。HIT 的治疗通常涉及缺乏逆转剂的替代抗凝剂，这可能会增加出血风险、延长住院时间并增加疑似 HIT 患者的成本。快速免疫测定有望改善 HIT 诊断的速度。这些检测必须保持对这种“不能错过”诊断的高度敏感性，同时具有足够的特异性以具有诊断价值。已经提出了一种使用两个连续的快速免疫测定的贝叶斯方法，将分析周转时间缩短至 60 分钟。这种方法有可能成为在改善 HIT 诊断的准确性和速度方面急需的临床进展。
