see also: [[Anorexia#Refeeding syndrome]] - [Rosen - hypophosphatemia](x-devonthink-item://9B254CA4-9017-4AEA-BCB0-ED0B7FB9E893?page=15&start=5249&length=16&search=HYPOPHOSPHATEMIA) **Severity** - mild - 0.6-0.75 mmol/L (2-2.5 mg/dL) - mod - 0.3-0.6 mmol/L (1-2 mg/dL) - severe - <3 mmol/L (1 mg<dL) # symptoms most pts with mild-mod ↓ PO4 asymptomatic *muscular* - weakness -- proximal most common - dysphagia or ileus - [[rhabdomyolysis]] - esp in EtOH withdrawl, DKA, and [[Anorexia#Refeeding syndrome]] - due to rapid uptake of PO4 into muscles *cardiac* - resp and cardiac failure in severe ↓ PO4 - reduced threshold for ventricular arrhythmias *CNS* - ALOC - [[Seizures]] - peripheral neuropathy - guillain-barre-like syndrom *haem* - haemolytic anaemia in severe ↓ PO4 - RBC unable to maintain cell membrane integrity - decreased O2 release in tissues due to decrease in 2,3 DPG - left-shift of Hb-O2 dissociation curve - impaired leucocyte function - impaired platelets # Management - DKA - routine PO4 doesn't affect outcome - increases risks of ↓ Ca and ↓ Mg - only replace if severe/symptomatic - mild-to-moderate asymptomatic ↓ PO4 - usually jsut tx cause - **PO4 0.08-0.16 mmol/kg BD** oral can be given, but usually *poorly tolerated due to diarrhoea* - ==Severe hypophosphataemia== 0.3-0.5 mmol/L - give up to 0.25 mmol/kg KPO4 (17.5 mmol for 70kg adult over 6 hours > 1mL of K2PO4 contains: > - 4.4mmol K+ > - 3 mmol of PO4 > > Initial replacement is IV infusion of 8 mmol K2PO4 over 6 hours > use NaPO4 in pts with impaired renal function ## adverse effects of PO4 infusion - common if too fast - ↓ Ca - **metastatic calcification** - crystal deposition in blood vessels, eye, lung, heart, kideny - hyperkalemia