An 82-year-old man with the chief complaint of anorexia was referred on suspicion pulmonary tuberculosis. He had undergone thyroidectomy because of thyroid cancer years ago, had taken levothyroxine sodium, and had kept plasma level of thyroidal mone within normal range. He had never pointed out hyponatremia. On laboratory findings on admission, serum natrium level was 125 mEq/l. A chest X-ray film showed infiltration in both lower lung fields, and a chest CT scan revealed a miliary pattern both lungs. Tubercle bacilli were detected from the sputum by the Ziehl-Neelsen staining ntituberculous drugs were started. On 5th hospital day, he developed conciousness disturbance, and the serum level of natrium and osmolarity was 103 mEq/l and 250 AgH20, respectively, while plasma ADH level was increased to 5.9 pg/ml/, and urine of natrium and osmolarity was 123 mEq/l and 394 mOsm/kgH20, respectively. His mental disturbance and hyponatremia gradually improved by supplementing NaCl. We diagnosed this case as SIADH associated with miliary tuberculosis. SIADH should considered when hyponatremia was occured in the case of miliary tuberculosis.
