ICU · Renal and metabolic

Phosphate disorders: hypophosphataemia and hyperphosphataemia in ICU

Also known as Hypophosphataemia · Hyperphosphataemia · Phosphate · Inorganic phosphate

Phosphate (PO4) is essential for ATP (energy), 2,3-DPG (oxygen release from Hb), cell membrane function (phospholipids), bone metabolism, and leukocyte/respiratory muscle function. HYPOPHOSPHATAEMIA (<0.8 mmol/L, phosphorus <2.5 mg/dL): COMMON in ICU (refeeding, sepsis, CRRT, diuretics, alkalosis) → RESPIRATORY FAILURE (diaphragm weakness — can't make ATP), WEAKNESS, CARDIAC dysfunction. MANAGEMENT: IV sodium/potassium phosphate — published ICU regimens are severity-banded (15–30 mmol over 3 h; up to 45 mmol over 3–6 h for severe, or weight-based 0.32–1 mmol/kg); oral if mild-moderate. HYPERPHOSPHATAEMIA (raised PO4 in acute illness): AKI (can't excrete), tumour lysis, rhabdomyolysis. MANAGEMENT: treat cause (RRT if AKI or severe tumour lysis); binders are for chronic CKD, not acute. Never give calcium reflexively — calcium-phosphate precipitation worsens AKI.

Checked against its sources on 14 Oct 2026