護理師準備給予心房顫動病人華法林（Warfarin）。給藥前應檢查哪項實驗室數值？
A nurse is preparing to administer warfarin to a client with atrial fibrillation. Which laboratory value should the nurse review before giving the medication?
- AHemoglobin level血紅素濃度
- BPlatelet count血小板計數
- CPartial Thromboplastin Time (PTT)部分凝血活酶時間 (PTT)
- DInternational Normalized Ratio (INR)✓ 正解國際標準化比值 (INR)
華法林（Warfarin）是一種維生素 K 拮抗劑，透過抑制肝臟凝血因子合成來產生抗凝血作用。其藥效受飲食與藥物交互作用影響極大，因此需嚴格監測國際標準化比值（INR）。治療目標通常設定在 2.0-3.0 之間（視適應症調整）。給藥前必須確認 INR 值，若數值過高表示出血風險增加，應即時暫停給藥並諮詢醫師。
Warfarin is a vitamin K antagonist that inhibits hepatic synthesis of clotting factors II, VII, IX, and X. Its effect is monitored by the INR (target generally 2.0-3.0, higher for some valve indications). The nurse must review the most recent INR before each dose: supratherapeutic INR increases bleeding risk and may require holding the dose. PTT monitors heparin therapy; platelets and hemoglobin are useful safety labs but not the dose-titration marker.