Assessment of Electrolyte Imbalances as an Early Manifestation of Refeeding Syndrome in Critically Ill Patients Receiving Total Parenteral Nutrition at a Tertiary Hospital in Mexico City

Introduction The nutritional status of critically ill patients is a key determinant of their clinical outcomes. Total parenteral nutrition (TPN) is an essential intervention when oral or enteral routes are not feasible, but it carries important risks such as hepatic and infectious complications, and particularly the development of refeeding syndrome (RFS), a potentially life-threatening condition associated with severe metabolic disturbances. Objectives The primary objective of the study was to determine the primary electrolyte imbalances associated with the development of RFS in critically ill patients receiving TPN. Secondary objectives were to determine the prevalence of RFS and evaluate the most effective prevention strategies in this population. Methods We conducted a retrospective descriptive study including critically ill hospitalized adults receiving TPN at Hospital Medica Sur, Mexico City, Mexico, between December 2024 and July 2025. Of 1,433 screened patients, 195 met the inclusion criteria. Clinical and laboratory data were collected from medical records with a seven-day follow-up after initiation of TPN. Outcomes studied were electrolyte disturbances (hypophosphatemia, hypokalemia, and hypomagnesemia) and prevalence of diagnosis of RFS using National Institute for Health and Care Excellence (NICE) diagnostic criteria. Logistic regression analyses adjusted for confounders were performed to identify associated factors (age, sex, BMI, significant weight loss, TPN duration, and nutritional risk with NRS-2002). R software (R Foundation for Statistical Computing, Vienna, Austria) was used for statistical analyses, with p < 0.05. Results A high prevalence of electrolyte imbalances was observed. Hypokalemia was documented in 37% of the study population (n = 73), hypophosphatemia in 36% (n = 71), and hypomagnesemia in 24% (n = 47). A dose-response relationship was identified: compared with patients without electrolyte alterations, the risk of RFS progressively increased with the presence of one (OR = 1.39, 95% CI: 1.27-1.52), two (OR = 2.54, 95% CI: 2.31-2.79), and three imbalances (OR = 2.55, 95% CI: 2.32-2.81). Conclusions RFS is a common complication in critically ill patients receiving TPN. The presence of electrolyte imbalances is directly and significantly associated with the development of this syndrome; Therefore, early identification allows the implementation of preventive interventions aiming at reducing the morbidity and mortality associated with nutritional support.