Intravenous phosphate in the intensive care unit: More aggressive repletion regimens for moderate and severe hypophosphatemia

Objective: To evaluate efficacy and safety of aggressive correction of hypophosphatemia with intravenous potassium phosphate in the ICU. Design and setting: Randomized interventional prospective study in the medical and surgical ICU of a tertiary university hospital. Patients: Critically ill patients with hypophosphatemia between June and November 1998. Measurements and results: Patients with moderate hypophosphatemia (<0.65 and >0.40 mmol/l; n=37) were randomized into two groups: group 1 received 30 mmol potassium phosphate intravenously in 50 ml saline over 2 h, and group 2 received 30 mmol potassium phosphate in 100 ml saline over 4 h. Patients with severe hypophosphatemia (<0.40 mmol/l; n=10) were also randomized into two groups: group 3 received 45 mmol potassium phosphate intravenously in 100 ml saline over 3 h, and group 4 received 45 mmol potassium phosphate in 100 ml saline over 6 h. Electrolytes, blood gas, renal function were monitored until day 3; urine was collected during and until 6 h after infusions. The overall efficacy of the protocols was 98% by the end of the infusion. There was no statistical difference in phosphate values between groups at the end of infusion or at 24 h. No adverse events were noted; one patient had an increase in serum potassium to 6.1 mmol/l. Phosphaturia in all groups was elevated as evidenced by fractional excretion above 20%. Conclusions: More rapid administration of large potassium phosphate boluses is effective and safe for correcting hypophosphatemia in ICU patients with preserved renal function if baseline serum potassium is below 4 mmol/l.