護理師照顧一位抗利尿激素分泌不當症候群（SIADH）患者。哪項實驗室檢查結果應立即通報醫師？
The nurse is caring for a client with syndrome of inappropriate antidiuretic hormone (SIADH). Which laboratory result should the nurse report to the healthcare provider immediately?
- AUrine specific gravity 1.030尿液比重 1.030
- BSerum osmolality 275 mOsm/kg血清滲透壓 275 mOsm/kg
- CUrine output 40 mL/hour尿量 40 mL/小時
- DSerum sodium 118 mEq/L✓ 正解血清鈉 118 mEq/L
SIADH 的核心病理生理是抗利尿激素（ADH）分泌過多，導致腎臟過度重吸收水份，產生「稀釋性低血鈉」。當血鈉下降至 120 mEq/L 以下時（選項 D 為 118），發生腦水腫、癲癇發作及昏迷的風險極高，屬於神經系統的醫療急症。選項 A（尿比重增加）與選項 B（血漿滲透壓低標）都是 SIADH 的預期臨床特徵，不一定需要「立即」通報，除非發生劇烈變化。選項 C（尿量 40 mL/hr）雖然偏少，但在 SIADH 患者中屬於常見發現（因水分被回收），且仍在正常範圍低標（30 mL/hr）。此題重點在於識別致命性的低血鈉。護理師必須理解 SIADH 會造成「水中毒」，首要介入是限水，而極低血鈉則需考慮給予高張鹽水（3% NaCl）。
The core pathophysiology of SIADH involves excessive secretion of antidiuretic hormone (ADH), causing the kidneys to reabsorb excessive water and producing dilutional hyponatremia. When serum sodium falls below 120 mEq/L (option D is 118), the risk of cerebral edema, seizures, and coma is very high—this represents a neurological medical emergency. Options B (elevated urine specific gravity) and B (low-normal serum osmolality) are expected clinical findings in SIADH and do not necessarily require immediate reporting unless they change drastically. Option C (urine output of 40 mL/hr) is on the low side but is a common finding in SIADH (because water is being reabsorbed) and remains above the lower limit of normal (30 mL/hr). The focus of this question is recognizing life-threatening hyponatremia. Nurses must understand that SIADH causes water intoxication; the primary intervention is fluid restriction, while severely low sodium may require hypertonic (3%) saline.
在美國護理實務中，血鈉低於 120-125 mEq/L 通常會自動觸發檢驗室的「危急值通報」（Critical Value Notification）機制，護理師需在限定時間內（如 15 分鐘）通知醫師。台灣亦有類似的醫學品質評鑑要求，但對 SIADH 的限水衛教，美國更強調與病人的契約式限水管理（Fluid contract）。