Phosphorus (PO₄)
BMP / ElectrolytesNormal range
3.0–4.5 mg/dL
SI: 0.97–1.45 mmol/L
Critical low: < 1 mg/dL · Critical high: > 8.9 mg/dL (context)
☎ When to call
Phos < 1.5 in a refeeding or ventilated patient — call; respiratory muscle failure is the risk.
What you do
- Phos and calcium see-saw — high phos usually means low Ca symptoms to watch
- Starting feeds on a malnourished patient? Watch phos daily — refeeding drops it fast
- Severe low phos = weak respiratory muscles — watch work of breathing
Causes of HIGH phosphorus
Causes of LOW phosphorus
Source: Pagana, Mosby's Manual of Diagnostic and Laboratory Tests, 7th ed.Reference only — verify against your facility's policy.
