Chronic versus new-onset hyponatremia in geriatric patients undergoing orthopedic surgery

Background: Hyponatremia is a common electrolyte disorder encountered in geriatric population undergoing an orthopedic surgery and is associated with adverse clinical outcomes. There is a paucity in literature comparing the effects of chronic- and new-onset hyponatremia on patient outcomes. Materials and Methods: A prospective study on 220 patients of age >= 60 years with an orthopedic injury was carried out over 1 year. The aim of this study was to determine the prevalence of chronic hyponatremia during hospitalization and the incidence of new-onset hyponatremia developing perioperatively and compare between the two groups with regard to the severity of hyponatremia, perioperative morbidities, serum sodium level trend in the early postoperative period, and mortality. Results: The prevalence of chronic hyponatremia was 14.1%, with an incidence of new-onset hyponatremia of 22.7%. Patients who developed new-onset hyponatremia were mostly of mild grade (130-134 mmol/L) and were significantly different from those with chronic hyponatremia who were more likely to be of profound grade (<125 mmol/L). When aggressively managed with adequate sodium corrections and strict monitoring, new-onset hyponatremia corrected within 48 h, whereas chronic hyponatremia had a gradual rise in serum sodium levels and did not achieve full correction within 48 h (P < 0.05). Those with chronic hyponatremia had a longer duration of hospital stay (P < 0.0001). No significant differences were obtained in mortality between the two groups. Conclusions: Patients developing new-onset hyponatremia are of milder grade and recover faster. Patients with chronic hyponatremia require a more cautious approach as they are more likely to be of profound grade and take longer time to correct.