[A case of syndrome of inappropriate antidiuretic hormone secretion in a patient with esophageal carcinoma possibly induced by cisplatin in neoadjuvant chemotherapy].
A 60 -year-old man complained of dysphagia and was admitted to our hospital for adjuvant chemotherapy under a diagnosis of esophageal carcinoma(squamous cell carcinoma[SCC], Stage II ). He was treated with cisplatin(CDDP)and 5- fluorouracil(5-FU). On the fifth day after administration, he experienced mild disorientation, and early morning on the sixth day, he showed impaired consciousness. Laboratory studies revealed a serum sodium level of 111mEq/L and a serum chloride level of 73mEq/L. The findings of computed tomography and magnetic resonance imaging of the head were unremarkable. Other laboratory studies revealed a plasma vasopressin level of 19.2 pg/mL, a plasma osmolality of 219mOsm/kg, a serum creatinine level of 0.61mg/dL, a serum cortisol level of 27.1 mg/dL, a urine osmolality of 665mOsm/kg, and a urine sodium level of 157.1mEq/L. There were no signs of dehydration, and so the patient was diagnosed with syndrome of inappropriate antidiuretic hormone secretion(SIADH). We discontinued chemotherapy and initiated fluid restriction and sodium supplementation. After this treatment, the patient's consciousness progressively improved. On the fifth day of treatment, laboratory studies revealed a serum sodium level of 138mEq/L and a serum chloride level of 98mEq/L, indicating recovery from hyponatremia.