- Epidemiology
- Starvation states (e.g., anorexia nervosa, chronic alcoholism, severe marasmus/malnutrition).
- Oncology pts, post-bariatric surgery, prolonged fasting (> 7-10 days).
- Pathophysiology
- Starvation -> depleted intracellular electrolytes (phosphate, potassium, magnesium) with normal/low-normal serum levels.
- Carbohydrate reintroduction -> insulin surge -> rapid intracellular shift of phosphate, potassium, magnesium, and water.
- Concomitant rapid utilization of thiamine (glycolysis cofactor).
- Sodium and water retention due to insulin action on renal tubules.
- Clinical Features
- Cardiovascular: Arrhythmias, CHF, pulmonary edema, prolonged QTc.
- Pulmonary: Respiratory muscle weakness, diaphragmatic failure.
- Neurological: Wernicke encephalopathy (confusion, ataxia, ophthalmoplegia), seizures, paresthesias, delirium. c
- Musculoskeletal: Rhabdomyolysis, diffuse muscle weakness, hyporeflexia.
- GI: Nausea, vomiting, abdominal distention.
- Diagnostics
- Initial/Screening: Baseline serum electrolytes (Phosphate, Potassium, Magnesium) in at-risk pts before starting nutrition.
- Key Labs: Severe hypophosphatemia (hallmark; < 1.85 mg/dL or > 30% drop from baseline), hypokalemia, hypomagnesemia. Elevated CK (if rhabdomyolysis occurs).
- Imaging/Other: ECG to screen for arrhythmias, prolonged QTc, or T-wave changes.
- Confirmatory/Gold Standard: Clinical diagnosis combining acute electrolyte drop (primarily phosphate) within 72 hours of starting refeeding with associated clinical signs (e.g., fluid overload, weakness).
- Management & Prevention
- Prevention/First-line: Screen high-risk pts. Check baseline PO4, K, Mg.
- Prophylaxis: Administer Thiamine (B1) before initiating any carbohydrate intake.
- Initiation: Start feeding slowly (e.g., 50% of energy requirements, 10 kcal/kg/day) and titrate up gradually over 3–7 days.
- Correction: Correct PO4, K, and Mg aggressively (often IV replacement needed).
- Monitoring: Check daily BMP and serum phosphorus levels; monitor fluid balance closely.