Hypernatremia and Copeptin Levels in the Elderly Hospitalized Patient

Abstract

Elderly patients have a high prevalence of hypernatremia. The aim of this study was to determine demographic and clinical characteristics of the elderly hypernatremic patient hospitalized in the internal medicine ward and to enhance understanding of the role of antidiuretic hormone (ADH) secretion in the pathogenesis of hypernatremia. Case-control study performed in an internal medicine ward in a university-affiliated hospital. Thirtythree elderly hypernatremic patients (admission sodium, >150 mEq/L; age, >70 years) were compared with 34 normonatremic patients. Demographic, functional (mental status and activities of daily living), clinical data (Acute Physiology and Chronic Health Evaluation [APACHE] II score), and serum copeptin levels as a marker of ADH secretion, were collected at admission. Mortality and change in the functional status were followed up to 30 days from discharge. Patients with hypernatremia presented with significantly lower baseline functional and cognitive states and higher APACHE II score (21.3 ± 8.6 vs. 15.4 ± 6.7; P<.01). Mortality within 30 days after discharge was higher in the hypernatremic group (58% vs. 32%; P<.05). Higher copeptin levels were found in the hypernatremic group compared to the normonatremic group (100.2 ± 60.6 pmol/L vs. 66.5 ± 57.2 pmol/L; P<.05). High levels of copeptin were associated with higher in-hospital (P<.05) and 30-day (P<.01) mortality. Sodium levels were found correlated with copeptin levels; yet, an even stronger correlation was found between copeptin levels and APACHE II score (r = 0.52; P<.001). Hypernatremia in the elderly at admission is associated with a high mortality rate. Copeptin level in the elderly seems to be a good single disease severity marker. ADH is strongly secreted in elderly hypernatremic patients. ADH = antidiuretic hormone APACHE = Acute Physiology and Chronic Health Evaluation.