5.一位62歲女性，長期服用amitriptyline治療憂鬱症(depression)，最近因stroke住院。病人無吞嚥困難，飲食正常，也沒有水腫。住院一週後抽血檢查發現serum [Na] 126 mEq/L，osmolality 262 mOsm/kg。urine [Na] 40 mEq/L，urine osmolality 398 mOsm/kg。病人hyponatremia的原因，最可能是?
(A)發生Renal sodium loss and dehydration
(B)發生Extra-renal loss of sodium, and fluid overload
(C)發生 lung cancer
(D)發生 SIADH (syndrome of inappropriate anti-diuretic hormone secretion)
(E)發生 stroke-induced central diabetes insipidus (DI)