How does D5 (Dextrose 5%) worsen refeeding syndrome?

How D5 Worsens Refeeding Syndrome

D5 (5% Dextrose) solution worsens refeeding syndrome primarily by triggering a rapid insulin response that causes dangerous intracellular shifts of electrolytes, particularly phosphate, potassium, and magnesium. 1

Mechanism of D5's Effect on Refeeding Syndrome

D5 solution contains concentrated glucose (50g/L) which, when administered to malnourished patients, can precipitate or exacerbate refeeding syndrome through several mechanisms:

1. Insulin Surge and Electrolyte Shifts

   • The sudden glucose load from D5 stimulates insulin secretion 1
   • Insulin promotes:
     • Cellular uptake of phosphate, potassium, and magnesium
     • Increased cellular glucose uptake
     • Shift from fat to carbohydrate metabolism

2. Specific Electrolyte Derangements

   • Hypophosphatemia: Most dangerous consequence 2, 1
     • Phosphate is essential for ATP production
     • Depletion leads to cardiac, respiratory, and neurological dysfunction
   • Hypokalemia: Causes cardiac arrhythmias and muscle weakness
   • Hypomagnesemia: Contributes to arrhythmias and neuromuscular symptoms

3. Carbohydrate-Specific Risk

   • Carbohydrates (like D5) pose the highest risk compared to proteins or fats 3
   • The European Society for Clinical Nutrition and Metabolism recommends limiting carbohydrate intake during initial refeeding 1

Clinical Implications and Prevention

To prevent D5-induced refeeding syndrome:

• Start with lower dextrose concentrations or avoid D5 entirely in high-risk patients 1

• Begin nutrition at 5-15 kcal/kg/day with gradual increase over 5-10 days 1

• Administer prophylactic electrolyte supplementation before initiating nutrition:

  • Phosphate: 0.3-0.6 mmol/kg/day
  • Potassium: 2-4 mmol/kg/day
  • Magnesium: 0.2 mmol/kg IV or 0.4 mmol/kg orally 1

• Provide thiamine (300mg IV) before initiating nutrition therapy to prevent Wernicke's encephalopathy 1

High-Risk Patient Identification

Patients at highest risk for D5-induced refeeding syndrome include those with:

• BMI <16 kg/m²
• Unintentional weight loss >15% in 3-6 months
• Little or no nutritional intake for >10 days
• Low baseline electrolyte levels 2
• Anorexia nervosa, chronic alcoholism, or oncologic conditions 1

Monitoring During Refeeding

When D5 or other nutrition is initiated in at-risk patients:

• Monitor electrolytes (phosphate, potassium, magnesium) closely during first 72 hours 1
• Watch for clinical signs of refeeding syndrome:
  • Fluid retention with peripheral edema
  • Cardiac arrhythmias
  • Respiratory failure
  • Neurological symptoms 2

Common Pitfalls to Avoid

1. Overlooking risk in obese patients who may still have malnutrition 1
2. Administering D5 without electrolyte supplementation in malnourished patients
3. Failing to administer thiamine before glucose-containing solutions like D5
4. Not recognizing that refeeding syndrome typically occurs within the first four days after nutrition therapy begins 2

The careful management of glucose administration, including avoiding or limiting D5 in high-risk patients, is essential to prevent the potentially life-threatening complications of refeeding syndrome.