Prevalence and risk factors of hyponatremia in hospitalized critically ill children: an observational study

Critically ill children frequently encounter the most common and potentially life-threatening electrolyte disturbances, i.e., hyponatremia. It is an independent risk factor for prolonged hospitalization in the intensive care unit and increased in-hospital mortality. Hyponatremia occurs in up to 20%-30% of admissions in the pediatric intensive care unit (PICU). This observational study was conducted in the PICU of a tertiary care hospital in a developing country from September 2018 to September 2019. Admission criteria in our PICU are the need for mechanical ventilation, fulminant hepatic failure, vasopressor support, respiratory failure and poorly controlled seizure. We studied 256 children, aged 1 month to 18 years, with normal serum sodium at admission. In our study, 72 (28.1%) children developed hyponatremia, and about two third (n=48, 66.7%) of them developed within 72 hours of admission in PICU. The majority of children (n = 46, 63.9%) in the hyponatremic group were below 5 years. Wasted children (n = 68, 26.6%) in the hyponatremic and isonatremic groups were 20 (27.8%) and 48 (26%), respectively. The most common etiology of hyponatremia was cerebral salt wasting syndrome (n = 20, 27.8%) followed by drug-induced cases (n = 19, 26.4%). The drugs responsible were diuretics and anti-epileptics. In our study, multiorgan failure (OR = 5.05, 95%CI = 1.90-13.43; p = 0.0001), shock (OR = 7.38, 95%CI = 3.56-12.28; p = 0.0001), vasopressor use (OR = 6.74, 95%CI = 3.45-13.17; p = 0.0001) and coagulopathy (OR = 6.74, 95%CI = 3.45-13.17; p = 0.0001) were the risk factors for the development of hyponatremia. Mortality among the hyponatremic group (44.4%) was significantly higher than in the isonatremic group (21.7%). Hyponatremia is a common electrolyte disturbance found in critically ill patients and is associated with prolonged hospitalization and increased mortality.