A 71-year-old man with squamous cell carcinoma of lung mimicking pulmonary tuberculosis associated with the syndrome of inappropriate secretion of ADH(SIADH). Laboratory examination showed serum sodium concentration of 108 mEq/l. serum osmolality 247 mEg/l urine sodium concentration of 141 mEq/l urine osmolality 547 mEq/l. normal levels (<0.56 pg/ml) of serum antidiuretic hormone (ADH). ADH release was regulated normally with changes in serum osmolality. SIADH was diagnosed on the basis of hyponatremia with corresponding serum hypoosmolality and a high urine osmolality due to continuous sodium excretion. In this case, SIADH was probably induced by increased renal sensitivity to ADH and suspected high serum ANP level of unknown origin.
Aged ; Atrial Natriuretic Factor ; Carcinoma, Squamous Cell* ; Humans ; Hyponatremia ; Inappropriate ADH Syndrome ; Lung* ; Osmolar Concentration ; Sodium ; Tuberculosis, Pulmonary*