下列哪位病患發生低血鈉的風險最高？
Which of the following clients is at the highest risk for developing hyponatremia?
- AClient on long-term steroid therapy接受長期類固醇治療的個案
- BClient with chronic diarrhea患有慢性腹瀉的個案
- CClient with diabetes insipidus患有尿崩症的個案
- DClient with SIADH✓ 正解患有抗利尿激素分泌不當症候群（SIADH）的個案
低血鈉（hyponatremia）的最高風險族群分析：C. SIADH（抗利尿激素分泌失調症候群）導致 ADH 過度分泌，腎臟過度保留水分而引發稀釋性低血鈉，是最直接、最高風險的疾病。其他選項：B. 慢性腹瀉造成 isotonic 體液流失（鈉與水同時流失），可能導致低血容量但血鈉常維持正常或輕度變化；B. 長期類固醇（皮質醇有 mineralocorticoid 作用）會引起鈉滯留與水分滯留，傾向高血鈉而非低血鈉；D. Diabetes insipidus（尿崩症）因 ADH 不足造成大量稀釋尿，反而是高血鈉的高風險。
Analysis of the highest-risk population for hyponatremia: C. SIADH (syndrome of inappropriate antidiuretic hormone secretion) causes excessive ADH secretion, leading the kidneys to retain water and producing dilutional hyponatremia—it is the most direct and highest-risk condition. Other options: A. Chronic diarrhea causes isotonic fluid loss (sodium and water are lost together), which may produce hypovolemia but sodium typically remains normal or only mildly altered; B. Long-term steroid therapy (cortisol has mineralocorticoid activity) causes sodium and water retention, trending toward hypernatremia rather than hyponatremia; D. Diabetes insipidus, due to insufficient ADH, results in massive dilute urine output, which is a high risk for hypernatremia.