護理師指導病人服用碳酸鋰（Lithium）。下列哪項安全指導最重要？

服用碳酸鋰（Lithium carbonate）是治療雙極性情感障礙（Bipolar Disorder）的常用藥物，但其治療窗（therapeutic window）狹窄，血中濃度過高容易引起毒性反應。因此，維持穩定的血藥濃度至關重要。 正確答案 D 是最關鍵的安全指導。鋰離子與鈉離子在腎臟的排泄機制相似，存在競爭關係。當病人攝入足夠且穩定的鈉時，鋰離子的排泄會維持在正常範圍；若鈉攝入量突然減少（如低鈉飲食或過度排汗），腎臟會試圖保留鈉，同時也減少鋰離子的排泄，導致血中鋰濃度升高，增加中毒風險。反之，若鈉攝入過多，可能導致鋰排泄過快，藥效不足。 錯誤選項 C（空腹服藥）可能加劇腸胃不適，但與維持藥效穩定性無直接關聯，通常建議隨餐或餐後服用。錯誤選項 A（限制飲水）是錯誤的，鋰鹽治療期間病人需要攝取足夠的水分（約 2.5-3 公升/天），以幫助排泄，避免脫水導致鋰濃度升高。錯誤選項 B（避免睡前服用）雖有時建議，但不如維持穩定鈉攝取來得關鍵，且依病人反應可調整。 臨床思路：護理師需教育病人關於鋰鹽的潛在風險與自我監測方法，包括定期抽血監測血藥濃度、注意中毒徵象，以及維持穩定的飲食與水分攝取。安全優先：鋰鹽中毒可能導致嚴重的神經系統損害甚至死亡，因此維持穩定的血藥濃度是安全用藥的關鍵。

Lithium carbonate is commonly used to treat bipolar disorder, but it has a narrow therapeutic window, and excessive serum levels readily produce toxicity. Maintaining a stable serum drug concentration is therefore critical. The correct answer, D, is the most important safety instruction. Lithium and sodium share similar renal excretion mechanisms and compete with one another. When the patient consumes an adequate and stable amount of sodium, lithium excretion remains within the normal range; if sodium intake decreases abruptly (such as with a low-sodium diet or excessive sweating), the kidneys retain sodium and simultaneously reduce lithium excretion, raising serum lithium levels and increasing the risk of toxicity. Conversely, excessive sodium intake can accelerate lithium excretion and result in subtherapeutic effects. Incorrect option C (taking the medication on an empty stomach) may worsen GI discomfort and has no direct relation to maintaining a stable drug level; lithium is generally taken with or after meals. Incorrect option A (limiting fluid intake) is wrong; patients on lithium need adequate fluid intake (approximately 2.5–3 liters per day) to support excretion and prevent dehydration-induced rises in lithium levels. Incorrect option B (avoiding bedtime dosing) is sometimes recommended, but it is less critical than maintaining a stable sodium intake and can be individualized based on patient response. Clinical reasoning: nurses must educate patients on the potential risks of lithium and on self-monitoring strategies, including routine serum level checks, recognition of toxicity signs, and maintenance of stable dietary and fluid intake. Safety priority: lithium toxicity can cause severe neurologic damage and even death, so maintaining a stable serum concentration is the cornerstone of safe medication management.

鋰鹽（Lithium）的治療與監測原則在台美兩地是相同的，都強調狹窄的治療窗、定期監測血中濃度、注意中毒徵象，以及維持穩定的鈉攝取與水分攝取。美國在藥物使用指引上可能更為細緻，但核心的臨床考量與病人教育重點一致。