Hypophosphatemia in a Specialized Intestinal Failure Unit: An Observational Cohort Study

Background: Patients with intestinal failure (IF) are prone to hypophosphatemia and shifts in magnesium and potassium levels. Although these shifts are often attributed to refeeding syndrome (RFS), the incidence of electrolyte shifts among patients with IF is unknown. We evaluated the occurrence of hypophosphatemia and other electrolyte shifts according to the functional and pathophysiological IF classifications.

Methods: We consecutively included all patients' first admission to an IF unit from 2013 to 2017. Electrolyte shifts were defined as severe hypophosphatemia <0.6 mmol/L (mM) or any 2 other shifts below reference range, comprising hypomagnesemia <0.75 mM, hypophosphatemia <0.8 mM, or hypokalemia <3.5 mM. Outcomes included length of stay, central line-associated bloodstream infection, and other infections. Mortality was evaluated 6 months after discharge.

Results: Of 236 patients with IF, electrolyte shifts occurred in 99 (42%), and 127 (54%) of these patients received intravenous supplementation with either phosphate, magnesium, or potassium. In patients who started parenteral nutrition, up to 62% of early-onset shifts (<5 days) related to refeeding, and up to 63% of late-onset shifts (≥5 days) could be ascribed to infections. Derangements occurred in 7 (18%) with type 1 IF, 53 (43%) with type 2 IF, and 39 (53%) readmitted patients with type 3 IF. Of 133 patients with IF secondary to short-bowel syndrome, 65 (49%) developed shifts.

Conclusion: In patients with IF, electrolyte shifts are frequent but not always due to RFS. Electrolyte shifts are common in patients with type 2 and those readmitted with type 3 IF.