Intravenous phosphate repletion regimen for critically ill patients with moderate hypophosphatemia

To document the safety and efficacy of an intravenous phosphate repletion regimen that is more aggressive than recommended by previously published guidelines, in intensive care unit (ICU) patients with hypophosphatemia.

Prospective evaluation of rapid, intravenous phosphate repletion in eligible patients.

Surgical ICU in a teaching hospital.

Patients with a serum phosphorus concentration of < 2 mg/dL (< 0.65 mmol/L) while in the ICU.

Enrolled patients received 15 mmol of sodium phosphate in 100 mL of 0.9% sodium chloride, infused intravenously over a period of 2 hrs. Patients with a serum potassium concentration of < 3.5 mmol/L received potassium phosphate, if no other potassium supplementation was ordered. The same dose could be repeated to a maximum of 45 mmol in a 24-hr period if either the 6-hr or follow-up (18- to 24-hr) postinfusion serum phosphorus remained < 2 mg/dL (< 0.65 mmol). Serum electrolytes, renal function, vital signs, and reflexes were closely monitored.

Eleven patients enrolled had baseline serum phosphorus values of 1.6 to 1.9 mg/dL (0.51 to 0.61 mmol/L). The serum phosphorus value immediately postinfusion was 2.3 to 5.3 mg/dL (0.74 to 1.7 mmol/L). Only one patient had a 6-hr postinfusion serum phosphorus of < 2 mg/dL (< 0.65 mmol/L), requiring two additional doses. Two other patients each required a second dose. Serum phosphorus was corrected in other patients with a single dose. No significant changes were noted in serum calcium, magnesium, or potassium concentrations, urine output, vital signs, or reflexes throughout the repletion period.

All patients were successfully repleted using the described protocol without any significant adverse effects. This repletion regimen may have widespread applicability in the ICU setting.