Causes and Outcome of Severe Hyponatremia in Elderly Hospitalised Patients in an Indian Teaching Hospital

Abstract

Introduction: Hyponatremia is the most frequent electrolyte abnormality encountered in clinical practice. The prospective studies on the causes and outcomes of severe hyponatremia are very few, and hence this study was undertaken. Objectives: To describe the clinical profile, aetiology and clinical outcomes of medical in-patients more than 60 years of age with severe hyponatremia (Serum Sodium ≤ 125 mEq/L) Methods: All the in-patients (≥ 60 years of age) admitted in medical units of a tertiary care hospital with severe hyponatremia (Sodium ≤125 mEq/L) at admission were recruited. Demographic profile, history, medication history, co-morbidities, clinical findings, Confusion Assessment Method score (CAM), Charlson comorbidity index and primary diagnosis for each patient was assessed. All relevant laboratory investigations were done. The patients were followed up till discharge for outcomes. The data were analyzed using SPSS 16.0 using appropriate statistical tests. Results: 109 patients were included in the study. 66% of them were males. The mean age was 69.9 years (SD 6.8). The mean sodium level was 117.6 (SD 6.2) mEq/L. 51.3% of the patients had delirium at admission. Hyponatremia was the sole cause for delirium in 31.5% of these patients. Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) was the most frequent cause for hyponatremia (34.8%). The median length of hospital stay was two weeks. At discharge, 11% of the patients were still in delirium. Drugs (especially thiazide diuretics) were found to be important contributory factors for hyponatremia. 2.8% of the patients died and 16.5% left against medical advice, due to deteriorating clinical status. Conclusion: Elderly patients with severe hyponatremia may not present with typical symptoms attributable to the metabolic abnormality. Nearly a third of the delirious patients were encephalopathic because of hyponatremia. The commonest cause for severe hyponatremia was SIADH (34.8%). Drugs (especially thiazide diuretics) were implicated as an important etiological factor for hyponatremia in about one-fifth of the patients. Cognitive status improved to near normal state in a majority of patients at discharge. Severe hyponatremia was not found to be a predictor of mortality.