Clinical presentation of hypernatremia in elderly patients: a case control study.

OBJECTIVES: To assess early clinical signs and their prognostic value in elderly patients with hypernatremia.

DESIGN: Prospective, case control study of 150 patients with hypernatremia matched to 300 controls.

SETTING: Multicenter study including seven short- and long-term geriatric care facilities.

MEASUREMENTS: Clinical assessment of hydration status at bedside, such as abnormal skin turgor or dry oral mucosa.

SECONDARY OUTCOME MEASURES: 30-day mortality rate and clinical indicators (assessed at the peak of natremia) associated with mortality.

RESULTS: Patients and controls were comparable in terms of drugs and underlying diseases, except for history of dementia, which was more frequent in patients than in controls. Patients were significantly more likely than controls to have low blood pressure, tachycardia, dry oral mucosa, abnormal skin turgor, and recent change of consciousness. Only three clinical findings were found in at least 60% of patients with hypernatremia: orthostatic blood pressure and abnormal subclavicular and forearm skin turgor. The latter two signs were significantly more frequent in patients with hypernatremia. Four other signs (tachycardia, abnormal subclavicular skin turgor, dry oral mucosa, and recent change of consciousness) had a specificity of greater than 79%. Using logistic regression, four signs were significantly and independently associated with hypernatremia: abnormal subclavicular and thigh skin turgor, dry oral mucosa, and recent change of consciousness. The mortality rate was 41.5% and was significantly higher in patients with hypernatremia. The status of consciousness when hypernatremia was diagnosed was the single prognostic indicator associated with mortality (odds ratio=2.3, 95% confidence interval=1.01-5.2).

CONCLUSION: Most of the classical signs of dehydration are irregularly present in patients with hypernatremia. Caregivers should carefully screen any variations in consciousness, because they may reveal severe hypernatremia.