There is no national guidance on the treatment of hypophosphataemia and practice varies widely across hospital Trusts. The guidance in this document reflects practice at Leeds Teaching Hospitals NHS Trust.
Phosphate replacement should be prescribed for patients with severe hypophosphataemia (serum phosphate concentration < 0.3 mmol/L). For patients with moderate hypophosphataemia (serum phosphate concentration 0.3 – 0.6 mmol/L), phosphate replacement should be considered if the patient is symptomatic or following a consideration of the clinical risks and benefits.
In moderate hypophosphataemia where the patient is asymptomatic, oral phosphate therapy should be considered if dietary modification is unsuitable. A dose of Phosphate Sandoz¨ effervescent tablets for hypophosphataemia is 1-2 tablets three times daily. The dose should be reviewed daily and adjusted according to phosphate levels.
In severe hypophosphataemia, in symptomatic patients and when the oral route is not appropriate, intravenous phosphate therapy may be considered. Doses for intravenous phosphate vary in the literature and suggested regimens have included 0.2-0.5mmol/kg/day up to a maximum of 50mmol (see Table in Q&A) however local practices may vary. Phosphates Polyfusor¨ is a commonly used product for this indication.
The required dose from a Phosphates Polyfusor¨ is usually given over 12 – 24 hours but can be given over 6 – 12 hours.
Phosphate is renally cleared. Phosphate (especially via the intravenous route) should be used with caution in patients with renal impairment.
Phosphates Polyfusors¨ should be administered with caution to patients with cardiac failure, peripheral or pulmonary oedema, impaired renal function or conditions predisposing to hyperkalaemia due to the potassium and sodium content of Phosphates Polyfusors¨.
Patients with hypocalcaemia should have their calcium corrected before replacing phosphate to prevent further hypocalcaemia.