A comparative study of the clinico-aetiological profile of hyponatremia at presentation with that developing in the hospital

BACKGROUND & OBJECTIVES Hyponatremia is a common problem encountered in patients presenting with nonspecific symptoms. We undertook this study to investigate the clinical profile of patients with hyponatremia, the precipitating factors, the response to therapy and to compare, using these parameters, hyponatremia at presentation to that developing in the hospital. METHODS Seventy consecutive patients with serum sodium less than or equal to 125 mmol/l at presentation or at any time during hospital admission were identified and studied using a proforma. The severity of hyponatremia, therapy given and time taken for recovery were analysed. RESULTS The mean age of patients was 48.1 ± 16.1 yr. The mean serum sodium was 117.8 ± 6.4 mmol/l. Confusion, headache and malaise were the most common symptoms, two patients had seizures, and 20.0 per cent patients showed no clinical manifestations. Nausea was significantly (P<0.05) more common in patients presenting with hyponatremia. 22 patients (31.4%) developed hyponatremia during their stay in the hospital. 3 patients (4.3%) presented with hyponatremia which got worse during the admission period. Most had multiple precipitating factors, decreased intake being the most common (82.9%), followed by increased losses (65.7%) and miscellaneous factors (70.0%). Drugs, fluid overload and inappropriate Ryle's tube feeds more commonly precipitated hyponatremia in in-hospital patients. Time taken for recovery showed negative correlation with the serum sodium. Patients with in-hospital hyponatremia took significantly longer time to recover (P<0.05). INTERPRETATION & CONCLUSIONS Decreased intake was found to be the commonest cause of hyponatremia, thus, ensuring adequate oral intake, especially in patients on liquid diet and in manual labourers, and correction of hyponatremia as soon as an abnormality is detected is important.