[Syndrome of inappropriate secretion of antidiuretic hormone associated with miliary tuberculosis]

An 82-year-old man with the chief complaint of anorexia was referred on suspicion of pulmonary tuberculosis. He had undergone thyroidectomy because of thyroid cancer 5 years ago, had taken levothyroxine sodium, and had kept plasma level of thyroidal hormone 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 the infiltration in both lower lung fields, and a chest CT scan revealed a miliary pattern in both lungs. Tubercle bacilli were detected from the sputum by the Ziehl-Neelsen staining. Antituberculous drugs were started. On 5th hospital day, he developed consciousness disturbance, and the serum level of natrium and osmolarity was 103 mEq/l and 250 mOsm /kgH2O, respectively, while plasma ADH level was increased to 5.9 pg/ml, and urine level of natrium and osmolarity was 123 mEq/l and 394 mOsm/kgH2O, respectively. His mental disturbance and hyponatremia gradually improved by supplementing NaCl. We diagnosed this case as SIADH associated with miliary tuberculosis. SIADH should be considered when hyponatremia was occurred in the case of miliary tuberculosis.