下列哪項評估結果是成年人脫水最可靠的指標？
Which assessment finding is the most reliable indicator of dehydration in an adult client?
- ASkin turgor on the forearm前臂之皮膚彈性
- BBlood pressure reading血壓讀數
- CPresence of dry mucous membranes黏膜乾燥之現象
- DSudden weight loss✓ 正解體重突然減輕
評估脫水（Dehydration）時，必須區分主觀感受與客觀指標。體重是反映液體容積狀態最敏感的指標，因為 1 公升的水約等於 1 公斤的體重，快速的體重下降通常代表體液流失。其他選項如皮膚彈性易受年齡影響（老人皮膚彈性差），黏膜乾燥易受口腔呼吸影響，血壓下降則是較晚期的代償失調表現，不如體重變化具備即時診斷意義。
When assessing dehydration, subjective symptoms must be distinguished from objective indicators. Body weight is the most sensitive indicator of fluid volume status because approximately 1 liter of water equals about 1 kilogram of body weight, so rapid weight loss usually reflects loss of body fluid. Other options such as skin turgor are easily affected by age (decreased turgor in older adults), mucous membrane dryness is influenced by mouth breathing, and a drop in blood pressure represents a late stage of decompensation. None of these provide the same immediate diagnostic value as changes in body weight.