Admission serum osmolarity and outcomes in critically ill children: A single-center prospective observational study

Background: Serum osmolarity plays a critical role in cellular homeostasis, fluid balance, and organ function, particularly in critically ill children. Hypo- and hyperosmolarity can result in organ dysfunction and poor outcomes. The objectives were to determine the incidence of abnormal serum osmolarity at pediatric intensive care unit (PICU) admission and to evaluate its association with admission pediatric sequential organ failure assessment (pSOFA) score and in-hospital mortality. Subjects and Methods: Children aged 1 month–18 years admitted to the PICU were screened . Exclusions were chronic kidney disease, diabetic ketoacidosis, and administration of intravenous fluids or medicines altering osmolarity before admission. Demographics, diagnoses, the main system involved, and treatment details were recorded. Children were grouped into hypo-osmolar (<289 mmol/L), normo-osmolar (290–309 mmol/L), and hyperosmolar (>310 mmol/L) categories based on admission serum osmolarity and were compared for pSOFA score, length of stay, need for mechanical ventilation, and mortality. Results: A total of 108 children were included and categorized into 3 groups: 61 (56.5%) had normal osmolarity, 44 (40.7%) had hypoosmolality, and 3 (2.8%) had hyperosmolarity. The median age was 5 (2–11) years; 62 (57.4%) were male, and the respiratory system was the most commonly involved (46.3%). The median pSOFA scores were higher among children with abnormal serum osmolarity at admission. The normo-osmolar group had no deaths, the hypo-osmolar group had 5 deaths (11.4%), and the hyperosmolar group had 1 death (33.3%), with P = 0.004. Conclusions: Abnormal serum osmolarity at admission was seen in nearly half (45%) of critically ill children and was associated with higher pSOFA scores and poor clinical outcomes.