Water and sodium disturbances predict prognosis of acute disease in long term cared frail elderly.

Elderly patients are at increased risk for developing infections and fever. We aimed to investigate the incidence, causes and outcome of hypernatemia and hyponatremia among elderly long-term care patients with febrile illness. This is a prospective study conducted in a 110 beds, nursing department for dependent elderly in geriatric long-term care facility during 20 months period. Changes in plasma sodium concentrations were found in 48% (132/270) of the febrile illness: during the acute illness in 38% (102/270) of the events and during the follow-up period after acute febrile event, in 30% (59/198) of the events. Upper respiratory tract, bronchial, lung, and urinary tract infections were the most common causes for the fever. Hypernatremia was more prevalent on acute febrile illness (63%). Hyponatremia was more common before the febrile illness (10%) and during the follow-up period (69%). The most common causes of hypernatremia were inadequate hydration or correction (57%) and continuous diuretic treatment (38%). The most common causes of hyponatremia were: Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) (38%), incorrect hydration (19%), and continuous diuretic treatment (30%). During the study, 60% (28/47) of the patients died, and hypernatremia was detected in 82% (20/28). Disturbances in sodium concentrations were predictors of bad outcomes, related to the underlying diseases burden, and were not related to the magnitude of the changes in plasma sodium, time of its development, advanced age, gender and coexisting changes in plasma potassium level.