What is the intravenous (IV) dose for severe hypophosphatemia?

From the Guidelines

For severe hypophosphatemia, the recommended IV dose is 5 mg/kg (maximum: 300 mg) over 20–60 min, as indicated by the most recent and highest quality study available 1. This dose can be adjusted based on the urgency of the situation and may be followed by a continuous infusion of 5mg/kg per min, increased to a maximum of 10mg/kg per min, with a concentration not exceeding 2 mg/mL and diluted with D5W. Key considerations for administration include:

• Adjusting the administration rate according to the urgency of the situation
• Monitoring for potential complications such as hypocalcemia, hyperphosphatemia, and calcium-phosphate precipitation
• Selecting the appropriate phosphate salt (sodium or potassium) based on the patient's electrolyte status
• Ensuring careful monitoring of serum phosphate levels after administration to guide further treatment. The IV route is preferred for severe cases due to the potential for oral supplementation to be insufficient in critically low phosphate levels or in patients with malabsorption, NPO status, or hemodynamic instability, as supported by the study 1.

From the FDA Drug Label

The maximum initial or single dose of potassium phosphates injection in intravenous fluids to correct hypophosphatemia is phosphorus 45 mmol (potassium 66 mEq). The recommended infusion rate for administration through a peripheral venous catheter is approximately phosphorus 6. 8 mmol/hour (potassium 10 mEq/hour).

The intravenous (IV) dose for severe hypophosphatemia is a maximum initial or single dose of phosphorus 45 mmol (potassium 66 mEq) with a recommended infusion rate of approximately phosphorus 6.8 mmol/hour (potassium 10 mEq/hour) through a peripheral venous catheter 2.

From the Research

Intravenous Dose for Severe Hypophosphatemia

• The intravenous dose for severe hypophosphatemia can be calculated using different methods, as seen in various studies 3, 4, 5, 6, 7.
• According to a study published in 1997, the phosphate solution was administered at a dosage of 2.5-3.0 mg phosphate/Kg body weight every 6-8 hours 3.
• Another study from 1983 used a solution containing 0.32 mmol of phosphorus per kilogram of body weight, infused intravenously over 12 hours and repeated every 12 hours until the serum phosphorus was greater than or equal to 2 mg/dl 4.
• A 2010 study recommended intravenous phosphate (0.16 mmol/kg) administered at a rate of 1 mmol/h to 3 mmol/h until a level of 2 mg/dL is reached 5.
• A 2018 study used an individualized regimen with a supplementation dose calculated according to the equation: phosphate dose (in mmol) = 0.5 x body weight x (1.25 - [serum phosphate]), with sodium-potassium-phosphate infused at a rate of 10 mmol/hour 6.
• A 2003 study used a Phosphates Polyfusor infusion of 50 mmol intravenous phosphate for the treatment of severe hypophosphataemia in refeeding syndrome 7.

Administration Rates and Durations

• The administration rates and durations of intravenous phosphate therapy vary depending on the study and the patient's condition 3, 4, 5, 6, 7.
• The 1997 study administered phosphate every 6-8 hours until the serum phosphate level reached 5.0-5.5 mg/dL 3.
• The 1983 study infused phosphorus over 12 hours and repeated every 12 hours until the serum phosphorus was greater than or equal to 2 mg/dl 4.
• The 2010 study recommended administering intravenous phosphate at a rate of 1 mmol/h to 3 mmol/h until a level of 2 mg/dL is reached 5.
• The 2018 study infused sodium-potassium-phosphate at a rate of 10 mmol/hour 6.
• The 2003 study administered a single Phosphates Polyfusor infusion of 50 mmol intravenous phosphate, with some patients requiring more than one infusion 7.