Treatment of neonatal hypophosphataemia

Hypophosphataemia is frequently encountered in neonatal patients, especially if they are small, premature or unwell. Although correction is possible through parenteral or enteral feeding, some patients do need additional intravenous supplementation.

The following case considers a hypophosphatemic premature neonate at 3 days of age with a body weight of 1.2 kg for whom we wish to supplement with 1.2 mmol/kg/day of phosphate.

Sodium glycerophosphate has the chemical formula of C₃H₇Na₂O₆P and a molecular mass of 216 g/mol, it is available as a 21.6% w/v solution which can be administered undiluted centrally.

What daily dose, in mmol, of phosphate is required to treat this child?

What volume, in ml, of 21.6% sodium glycerophosphate will be needed to provide the daily dose calculated in Question 1?

The infusion rate for undiluted solution will be too low to administer through a rate controlled pump, so if you dilute 10 ml of 21.6% solution to 50 ml what infusion rate should the pump be set at, in ml/hour?