A 64-year-old woman was admitted for evaluation of
hyponatremia. She was maintained on hypertonic saline administration. Without this
therapy, the serum Na concentration decreased progressively to 127 mEq/L and the plasma osmolality to 254 mOsm/Kg H2O, on Day 3. At that time, the concentration of
antidiuretic hormone (ADH) was as high as 3.5 pg/ml. A skull radiogram revealed an enlarged sella turcica. Computed tomography (CT) revealed a low density in the sella, and magnetic resonance imaging revealed equal intensity of the sella turcica and the cerebrospinal fluid. A diagnosis of
empty sella syndrome was made by
metrizamide cisternography in conjunction with CT scanning. A diagnosis of
panhypopituitarism was made by endocrine function tests. 123I-thyroidal uptake was 6% when her serum TSH was 10.9 microU/ml, suggesting that she might also have
primary hypothyroidism. When this patient was given
glucocorticoid before
levothyroxine replacement, her serum Na concentration rose up to about 140 mEq/L and a normal relationship between her plasma ADH level (2.4 pg/ml) and plasma osmolality (281 mOsm/kg H2O) was restored. Therefore, it was suggested that ADH hypersecretion induced by the
glucocorticoid deficiency might in part contribute to the development of
hyponatremia. This is the case of primary empty syndrome associated with
panhypopituitarism, in whom initial symptom was caused by
hyponatremia.