[Hypernatremia in the aged: clinical characteristics].

Objective: Hypernatremia in young adults is a rare condition, sometimes occurring after gastrointestinal diseases, osmotic diuresis or diabetes insipidus. The clinical characteristics and prognosis of hypernatremia in geriatric patients would be different. Each case must be examined separately.

Patients And Methods: We conducted a prospective uncontrolled study among patients over 70 with sodium levels equal to or greater than 150 mmol/l (at admission or during the hospitalization).

Results: Hypernatremia was found in 77 patients. Mean age was 84.1 +/- 6.7 years. The mean peak serum sodium level was 157.3 +/- 7.4 mmol (two-thirds ranged from 150 to 160). Hypernatremia onset was produced by a wide range of symptoms: 48% had a febrile illness, 470% were on diuretics, 15% had had a stroke, but only 9% were suffering from diarrhea or vomiting. Most of the patients had disabling chronic illnesses (62% loss of two or more ADL of Katz), severe dementia (84% level = 6 on the Reisberg global deterioration scale). In spite of fluid replacement and follow-up treatment, outcome was poor: 62% of the patients died within three months.

Conclusion: Besides digestive and renal losses, hypernatremia in elderly patients is increased by fluid supply disorders consecutive to hypodipsia contracted at the same time as disability and dementia. Hypodipsia is a sign of poor prognosis. Prevention must be undertaken early, emphasizing the importance of identifying dehydration early among elderly people with chronic disabling illnesses.