Definition: Phosphate (Phos) < 2.5 mg/dL Causes

• Refeeding Syndrome
• Liver Resection (Significant Requirements for Hepatocyte Regeneration)
• Hyperparathyroidism
• Acute Respiratory Alkalosis and Hyperventilation
• Malnutrition with Poor Oral Intake
• Medications (Antacids)
• Chronic Diarrhea
• Urinary Phosphate-Wasting Syndromes (Fanconi Syndrome, etc.)
• Renal Replacement Therapy

Presentation

• Decreased Intracellular ATP and Failure of Energy-Dependent Functions
  • Diaphragm Weakness – May Cause Failure to Wean from Ventilator
  • Myocardial Contractility Impairment
  • Metabolic Encephalopathy
  • Myopathy
  • Ileus
• Impaired Renal Reabsorption of Calcium and Magnesium (Can Be Dramatic but Mechanism is Unknown)

Treatment

• Primary Treatment: Phosphate Replacement

• Sodium Phosphate (Na-Phos)
  • IV Correction: Every 15 mmol will Increase Serum Phos 0.4 mg/dL
  • Generally Preferred Over K-Phos
  • Enteral Dosing:
    • Oral Bioavailability is Highly Variable – Dose Should Be Tripled
    • 250 mg PO is Equivalent to 8 mmol
    • Generally Given in 3-4 Doses Over the Day
  • Rechecking After Replacement: Wait 2-4 Hours

• Potassium Phosphate (K-Phos)
  • Same Correction as Na-Phos
  • Also Provides 22 mEq K per 15 mmol

• Goal is to Achieve the Middle of the Normal Range, Not the Lower Limit of Normal, to Allow for Ongoing Losses