Oh TK, et al. - Researchers examined 90-day mortality and morbidity following noncardiac surgery in relation to preoperative hyperchloremia or hypochloremia, as evaluated using preoperative serum chloride tests, in this retrospective cohort analysis. Participants were patients > 20 years of age who had a noncardiac surgery between January 2010 and December 2016. For these patients, medical records were reviewed. Depending on the outcomes of serum chloride testing done within 1 month prior to surgery, patients were classified into one of the following groups: normochloremia, 97–110 mmol·L⁻¹; hyperchloremia, > 110 mmol·L⁻¹; and hypochloremia, < 97 mmol·L⁻¹. The final analysis included 106,505 patients. Findings revealed increased 90-day mortality following noncardiac surgery in relation to preoperative hypochloremia and hyperchloremia. Also, an increased risk for postoperative acute kidney injury was observed in relation to preoperative hypochloremia.