Refeeding Hypophosphatemia Among Critically Ill Surgical Patients: A Prospective Analysis of Incidence, Risk Factors, and Clinical Outcomes

Background: This study aimed to determine the incidence of refeeding hypophosphatemia (RH) in critically ill surgical patients admitted to the surgical intensive care unit, to identify associated risk factors, and to evaluate its impact on clinical outcomes. Methods: This prospective observational study included 135 patients admitted to the general surgery ICU for ≥48 h, with 109 included in the final analysis. Clinical, nutritional, and laboratory data from the first five ICU days were collected and evaluated. According to the baseline phosphorus level, a 10–20% decrease was classified as mild RH, a 20–30% decrease as moderate RH, and a decrease of more than 30% as severe RH. Results: Serum phosphorus levels over the first five days were 3.89 ± 1.5, 3.44 ± 1.6, 3.20 ± 1.6, 3.13 ± 1.7, and 3.35 ± 1.8 mg/dL, respectively, with the lowest level on Day 4. The overall RH incidence was 76% (11% mild, 11% moderate, 54% severe). In multivariable analysis, lower albumin, decreased HCO3 and higher WBC were associated with RH. Reoperation (18%) and shock (14%) were the most common complications. Mechanical ventilation was required in 62% of patients. Median ICU stay was 8 days, and ICU mortality was 22%. Conclusion: Refeeding hypophosphatemia is highly prevalent among critically ill surgical patients, with more than half of affected patients developing severe hypophosphatemia. Higher disease severity, hypoalbuminemia, and vasopressor use were identified as significant risk factors for RH.