Synopsis
Recognise acute phosphate-related respiratory and cellular dysfunction, prevent refeeding harm and manage renal phosphate excess without unsafe replacement.
- Phosphate is essential for ATP, 2,3-DPG, cell membranes, signalling and bone mineral, so severe deficiency can impair diaphragm, myocardium, brain, erythrocytes and leukocyte function.
- A rapid intracellular shift follows refeeding, insulin treatment, respiratory alkalosis and recovery from DKA, and can produce profound symptoms despite a smaller preceding extracellular abnormality.
- NICE identifies low phosphate, potassium or magnesium and prolonged minimal intake as major refeeding-risk features; prevention begins before calories are advanced.
Key red flags
New difficulty weaning ventilation, shallow breathing, weak cough or reduced vital capacity can reflect severe phosphate depletion and warrants urgent confirmation and replacement.
Investigation priorities
Confirm direction and assess reciprocal calcium change and precipitation risk.
Management branches
An adult has prolonged minimal intake, major weight loss, alcohol dependence or low baseline phosphate, potassium or magnesium.
- Apply NICE CG32 refeeding-risk criteria before nutrition, obtain baseline electrolytes and glucose and prescribe thiamine and multivitamin support through the local nutrition protocol.
- Start energy at the guideline rate appropriate to risk and replace potassium, phosphate and magnesium through planned oral, enteral or intravenous routes rather than waiting for symptoms.
Key medicines
Oral phosphate replacementChoose the current local licensed or approved preparation and divided dose according to phosphate concentration, symptoms, gastrointestinal tolerance, sodium and potassium content and renal function; confirm the specific product rather than converting by tablet count.
Intravenous phosphate replacementUse only the organisation’s pharmacy-approved sodium- or potassium-phosphate product, dilution, line and infusion rate, with dose selected from the current measured level, symptoms, body size and renal function and reviewed before repetition.