What are the contents of Total Parenteral Nutrition (TPN)?

Contents of Total Parenteral Nutrition (TPN)

Total Parenteral Nutrition (TPN) contains amino acids, glucose, lipids, electrolytes, vitamins, and trace elements administered intravenously to provide complete nutritional support when the enteral route cannot be used. 1, 2

Core Components of TPN

Macronutrients

• Carbohydrates:

  • Provided as dextrose (glucose monohydrate)
  • Provides 3.4 kcal/mL
  • Maximum infusion rate: 5-7 mg/kg/min 1
  • Blood glucose should be maintained at 180-200 mg/dL 1

• Proteins:

  • Provided as free amino acids
  • Dosage: 1.0-1.5 g/kg/day based on ideal body weight for adults 1
  • Higher amounts needed for infants and children

• Lipids:

  • Typically provides 20-30% of total calories 1
  • 20% lipid emulsion is more calorically dense than dextrose
  • Serum triglyceride levels should be kept below 400-800 mg/dL 1

Micronutrients

• Vitamins:

  • Water-soluble vitamins (B1, B2, B3, B6, B12, biotin, folate, C)
  • Fat-soluble vitamins (A, D, E, K)
  • Specific dosing recommendations 1:
    • Vitamin A: 10,000-50,000 units daily
    • Vitamin B12: 300 μg subcutaneously monthly (for terminal ileal resections)
    • Vitamin C: 200-500 mg
    • Vitamin D: 1600 units DHT daily
    • Vitamin E: 30 IU daily
    • Vitamin K: 10 mg weekly

• Trace Elements:

  • Zinc: 220-440 mg daily (sulfate form)
  • Selenium: 60-100 μg daily
  • Others as needed (iron, copper, manganese, etc.)

• Electrolytes:

  • Sodium, potassium, calcium, magnesium, phosphate, chloride
  • Bicarbonate as needed
  • Dosing must be individualized based on serum levels 1

Administration Considerations

Route of Administration

• Central venous access is required for standard TPN due to high osmolarity 3
• Peripheral administration is possible with lower nutrient concentration and larger volume 3

Dosing Parameters

• Energy requirements: 25-30 kcal/kg/day based on ideal body weight 1, 2
• Insulin requirements: May be added to TPN at initial dose of 0.1 U/g dextrose if needed 1
• Fluid requirements: Individualized based on clinical status

Monitoring Requirements

• Blood glucose monitoring (at least daily, optimally four times daily) 1
• Electrolyte levels
• Fluid status
• Triglyceride levels
• Liver function tests

Clinical Considerations

• Initially administered continuously while addressing postoperative complications 1
• For home TPN, infusion is typically compressed to overnight schedule 1, 2
• Metabolic complications include hyperglycemia, hypertriglyceridemia, and electrolyte imbalances 3
• Catheter-related complications include mechanical problems and infections 4

Special Populations

• Infants and children require higher levels of support per kg of body weight 1
• Patients with glucose intolerance may require higher percentage of lipid calories 1
• Patients with renal or hepatic dysfunction require modified formulations

TPN formulations should be tailored to meet individual nutritional requirements based on clinical status, but the core components remain consistent across standard preparations.