護理師正在檢視病人的用藥清單，注意到病人正在服用華法林。監測此藥物必須進行哪項實驗室檢查？
A nurse is reviewing a client's medication list and notes the client is taking warfarin. Which laboratory test is essential for monitoring this medication?
- AActivated partial thromboplastin time (aPTT)活化部分凝血活酶時間 (aPTT)
- BComplete blood count (CBC)全血細胞計數 (CBC)
- CBlood urea nitrogen (BUN) and creatinine尿素氮 (BUN) 和肌酸酐
- DProthrombin time (PT) and International Normalized Ratio (INR)✓ 正解凝血酶原時間 (PT) 和國際標準化比值 (INR)
華法林（Warfarin）是維生素 K 拮抗劑，透過抑制肝臟合成凝血因子 II、VII、IX 和 X 來產生抗凝血作用。因為個體對藥物的代謝差異大且易受食物（如維生素 K）影響，必須定期抽血監測凝血功能。PT 用於評估外在路徑凝血功能，而 INR 則是將 PT 標準化後的數值，能排除不同實驗室試劑差異，是調整華法林劑量的國際金標準。
Warfarin is a vitamin K antagonist that inhibits hepatic synthesis of clotting factors II, VII, IX, and X. Because individual response varies and dietary vitamin K affects activity, regular monitoring is essential. PT measures the extrinsic pathway and INR standardizes PT across laboratories—INR is the international gold standard for adjusting warfarin therapy.
在台灣與美國，華法林的監測均高度依賴 INR。臨床上，美國醫院多設有專門的抗凝血門診（Anticoagulation Clinic）或由藥師（PharmD）根據實驗室報告調整劑量，護理師需確保病人了解定期回診抽血的重要性。