Association between Serum Osmolality and Acute Kidney Injury in Critically Ill Patients

A BSTRACT Introduction: Serum osmolality may predict the development of acute kidney injury (AKI) at an earlier stage, even before changes in biochemical parameters, such as serum creatinine become evident and may help prevent AKI in intensive care unit (ICU) settings. The present study was conducted to investigate the association between serum osmolality and AKI in critically ill patients. Methods: This observational study was conducted between April 2022 and June 2023 in the ICU of a tertiary care hospital. A total of 1,300 ICU patients aged 18 years or older were included. The primary and secondary objectives were to determine the incidence of abnormal serum osmolality at admission and to find an association of serum osmolality with AKI and mortality in critically ill patients. Results: Serum osmolality was <280 mmol/L in 547 patients (42.1%), between 280 and 295 mmol/L in 692 patients (53.2%), and >295 mmol/L in 61 patients (4.7%). AKI developed in 346 patients (26.6%), and 75 patients (5.8%) succumbed. Age, presence of diabetes mellitus, serum osmolality <280 mmol/L and >295 mmol/L, and the median duration of ICU stay were significantly associated with the development of AKI. AKI Stage 3 and serum osmolality >295 mmol/L were significantly associated with inhospital mortality. Multivariate analysis revealed that a hospital stay >10 days and serum osmolality <280 mmol/L or >295 mmol/L at the time of admission were significantly associated with AKI. Conclusions: High or low serum osmolality at the time of admission were significantly associated with an increased risk of developing AKI in critically ill patients.