Towards Safer Phosphate Repletion: A 24-Hour Weight-Based Infusion Protocol for Hypophosphatemic ICU Patients

Abstract

Background: Evidence on the safety and efficacy of phosphate (P) replacement in hypophosphatemic intensive care unit (ICU) patients remains limited. Objectives: To evaluate the efficacy and safety of a 24-hour weight-based intravenous phosphate replacement protocol. Methods: Adult ICU patients with hypophosphatemia received potassium acid phosphate (25 mL) diluted in 500 mL of saline or 5% glucose, administered via infusion pump. Dosing was 0.3 mmol/kg/24 h for mild hypophosphatemia (0.65 - 0.73 mmol/L) and 0.6 mmol/kg/24 h for moderate to severe cases (≤ 0.64 mmol/L). Phosphate levels were measured every 24 hours. Efficacy was defined as normalization of phosphate within 24 hours. Safety outcomes included hypocalcemia, hypotension, hyperphosphatemia, hyperkalemia, and acute kidney injury. Results: Among 134 patients (aged 67.6 ± 14.6 years; 55% female; median APACHE II median 18), 197 hypophosphatemia episodes were treated. Phosphate normalized within 24 hours in 121 episodes (61%). Mild adverse events occurred in 28 patients (21%); no severe complications were reported. Conclusions: This protocol is not a replacement for standard guidelines in symptomatic hypophosphatemia and unstable patients. It proved effective and generally safe in critically ill patients with mild to severe hypophosphatemia, offering a feasible approach in resource-limited ICU settings where oral formulations are unavailable and frequent laboratory monitoring is unfeasible.