服用肝素（Heparin）點滴的病人，哪項實驗室檢查是必要的？

肝素（Heparin）是一種抗凝血劑，其療效監測指標為部分凝血活酶時間（aPTT）。由於肝素的作用機轉是加強抗凝血酶 III（Antithrombin III）對凝血因子的抑制，會延長內源性凝血路徑，因此臨床需透過 aPTT 調整劑量。PT/INR 則用於監測 Warfarin 的療效，兩者不可混淆。

Activated partial thromboplastin time (aPTT) is the essential laboratory test to monitor heparin therapy because heparin affects the intrinsic coagulation pathway. While platelet counts are important for detecting heparin-induced thrombocytopenia, aPTT specifically measures the therapeutic efficacy of the anticoagulant.