What are the essential amino acids requirements for cancer patients receiving parental (parenteral) nutrition?

Essential Amino Acid Requirements for Cancer Patients on Parenteral Nutrition

Cancer patients receiving parenteral nutrition require amino acids at a rate of 1.2-2.0 g/kg/day, with specific attention to glutamine supplementation at 0.2-0.4 g/kg/day when indicated. 1

Amino Acid Requirements in Cancer Patients

General Requirements

• The optimal nitrogen supply for cancer patients on parenteral nutrition ranges between:
  • Minimum amino acid supply: 1.0 g/kg/day
  • Target amino acid supply: 1.2-2.0 g/kg/day 1
• Higher protein requirements (closer to 2.0 g/kg/day) are recommended for patients with:
  • Severe malnutrition
  • Cachexia
  • Ongoing weight loss
  • Hypercatabolic states 1, 2

Specific Amino Acid Considerations

Glutamine

• When parenteral nutrition is indicated in cancer patients, the amino acid solution should contain 0.2-0.4 g/kg/day of L-glutamine (equivalent to 0.3-0.6 g/kg/day alanyl-glutamine dipeptide) 1
• Benefits of glutamine supplementation:
  • Improved immune function
  • Enhanced gut barrier function
  • Reduced infectious complications
  • Better glycemic control 1
• Glutamine becomes conditionally essential in cancer patients due to increased demand and decreased endogenous production 1

Essential Amino Acids

• Cancer patients often show deficiencies in specific essential amino acids:
  • Branched-chain amino acids (valine, leucine)
  • Threonine
  • Methionine
  • Lysine 3
• These deficiencies may persist during treatment, particularly during chemotherapy 3

Clinical Application

Indications for Parenteral Nutrition in Cancer Patients

• Parenteral nutrition is indicated when:
  • Patients are unable to meet nutritional requirements orally or enterally
  • Inadequate food and enteral intake (<60% of estimated energy expenditure) is anticipated for more than 10 days 1
  • Patients have severe mucositis or radiation enteritis 1
  • Patients have malignant obstruction or partial obstruction of the gastrointestinal tract 1

Monitoring and Adjustments

• Regular monitoring of:
  • Nitrogen balance
  • Plasma amino acid levels
  • Renal function
  • Liver function
  • Electrolyte balance 1
• Adjust amino acid provision based on:
  • Clinical response
  • Metabolic status
  • Presence of organ dysfunction
  • Concurrent treatments (e.g., chemotherapy, radiation) 1

Special Considerations

Home Parenteral Nutrition (HPN)

• For patients requiring long-term parenteral nutrition:
  • Maintain amino acid requirements at 1.2-2.0 g/kg/day
  • Consider supplemental nocturnal HPN (20-25 kcal/kg/day; 0.10-0.15 g nitrogen per kg per day) for weight-losing cancer patients 1

Hematopoietic Stem Cell Transplantation (HSCT)

• HSCT patients may benefit from glutamine-supplemented parenteral nutrition 1
• Reserve PN for those with severe mucositis, ileus, or intractable vomiting 1

Common Pitfalls to Avoid

1. Underestimating protein requirements: Cancer patients often have higher protein needs than non-cancer patients due to increased catabolism and inflammation 2

2. Overlooking specific amino acid deficiencies: Regular monitoring of plasma amino acid levels can help identify and correct specific deficiencies 3

3. Inappropriate use of PN: PN is not recommended for non-aphagic oncological patients in whom there is no gastrointestinal reason for intestinal failure 1

4. Ignoring glutamine supplementation: When PN is indicated, glutamine supplementation should be considered standard of care for cancer patients 1

5. Excessive protein provision: While meeting requirements is important, excessive protein provision can lead to azotemia and metabolic stress, particularly in patients with compromised renal function 4

By addressing these essential amino acid requirements in parenteral nutrition for cancer patients, clinicians can optimize nutritional support, potentially improving clinical outcomes, quality of life, and treatment tolerance.