Enteral Phosphate Replacement in the Intensive Care Unit

Background: Enteral phosphate replacement offers multiple advantages over intravenous phosphate replacement, but optimal dosing and administration are unclear. Objective: This study aimed to compare 2 different dosing strategies (PRE vs POST) of enteral phosphate replacement for mild hypophosphatemia (serum phosphorus = 2.1-2.5 mg/dL) and to evaluate our dosing strategy for moderate hypophosphatemia (serum phosphorus = 1.5-2 mg/dL) in critically ill patients. Methods: This single-center quasiexperimental, institutional review board–approved study was conducted in adult patients admitted to an intensive care unit (ICU) who received enteral phosphate replacement with a follow-up serum phosphorus level obtained within 24 hours of replacement. Patients were excluded if they had diabetic ketoacidosis, acute kidney injury, or received total parenteral nutrition or targeted temperature management. The mild PRE and POST groups received 48 and 72 mmol of enteral phosphate, respectively. The moderate group received 72 mmol of enteral phosphate. Effectiveness outcomes included normalization of serum phosphorus, defined as 2.6 to 4.5 mg/dL, and median change in phosphorus concentration. Safety outcomes included the incidence of new onset diarrhea and hyperphosphatemia (serum phosphorus >4.5 mg/dL) within 24 hours after phosphate replacement. Results: Of the 138 patients included, the median age was 59 (44-70) years and 69.6% were admitted to the surgical trauma ICU. Normalization of serum phosphorus occurred in 55 (58.2%) patients in mild PRE and 44 (72.7%) patients in mild POST ( P = 0.13). Change in serum phosphorus was 0.4 (0.1-0.9) mg/dL in mild PRE vs 0.7 (0.3-1.2) mg/dL in mild POST ( P = 0.06). Normalization occurred in 39 (66.7%) patients in the moderate group with a change in serum phosphorus of 1.0 (0.6-1.6) mg/dL. Rates of new onset diarrhea and hyperphosphatemia were not significantly different between groups. Conclusion and Relevance: Enteral phosphate replacement appears safe and effective in critically ill patients with mild-to-moderate hypophosphatemia and may serve as an alternative to intravenous phosphate.