Hypernatremia in the acutely ill elderly patients: role of impaired arginine-vasopressin secretion.

Hypernatremia, a common finding among the elderly, is believed to be due to water deficit. In the present study, in 12 consecutive hospitalized elderly patients (mean age 82.2 years) with moderate to severe hypernatremia (mean serum sodium 166.9 mEq/l), inappropriately low plasma levels of vasopressin were found in relation to serum osmolality (mean 1.8 pg/ml and 343 mosmol/l, respectively). All patients but 1 were hospitalized with acute febrile disease and all but 2 had underlying neurological disease. Hypernatremia persisted for at least 3 days despite the patients' rehydration. It seems, therefore, that temporary hypernatremia in elderly patients with acute febrile disease, especially in the presence of underlying neurological disorder, reflects an inadequate vasopressin response to the hyperosmolar state.