🍓Medical Nutrition Therapy II Unit 5 – Nutrition Support for Dialysis Patients

Key Concepts in Dialysis and Nutrition

• Dialysis serves as a life-sustaining treatment for individuals with end-stage renal disease (ESRD) by removing waste products and excess fluid from the blood
• Two main types of dialysis include hemodialysis, which uses an artificial kidney machine to filter the blood, and peritoneal dialysis, which utilizes the peritoneal membrane as a natural filter
• Adequate nutrition plays a crucial role in maintaining the health and well-being of dialysis patients, as they are at increased risk for malnutrition and other nutrition-related complications
• Protein-energy wasting (PEW) commonly occurs in dialysis patients due to factors such as increased catabolism, inflammation, and loss of nutrients during the dialysis process
• Nutritional management focuses on providing appropriate amounts of macronutrients (protein, carbohydrates, and fats) and micronutrients (vitamins and minerals) to meet the unique needs of dialysis patients
• Regular nutrition assessments and monitoring are essential to identify and address nutritional deficiencies or imbalances in dialysis patients

Nutritional Needs of Dialysis Patients

• Protein requirements are higher for dialysis patients compared to the general population, with recommendations ranging from 1.2 to 1.4 g/kg body weight per day to promote muscle mass maintenance and prevent PEW
• Energy needs are individualized based on factors such as age, sex, physical activity level, and body composition, with a general recommendation of 30-35 kcal/kg body weight per day
• Adequate fiber intake (20-30 g/day) is important for maintaining bowel regularity and promoting the growth of beneficial gut bacteria
• Dialysis patients often require phosphorus, potassium, and sodium restrictions to prevent complications such as hyperphosphatemia, hyperkalemia, and fluid overload
  • Phosphorus intake is typically limited to 800-1000 mg/day
  • Potassium intake is usually restricted to 2000-3000 mg/day
  • Sodium intake is often limited to 2000-2300 mg/day
• Fluid intake is closely monitored and adjusted based on the patient's residual kidney function, urine output, and interdialytic weight gain, with a common recommendation of 1000 mL/day plus the volume of urine output

Macronutrient Considerations

• Protein intake should be closely monitored to ensure adequate intake while minimizing the accumulation of waste products (urea) that can lead to uremic toxicity
  • High-quality protein sources (eggs, lean meats, fish) are preferred to maximize essential amino acid intake
  • Plant-based protein sources (legumes, nuts, seeds) can be incorporated but may require careful planning to ensure adequate essential amino acid intake
• Carbohydrate intake should be balanced to provide sufficient energy while minimizing the risk of hyperglycemia, especially in patients with diabetes
  • Complex carbohydrates (whole grains, fruits, vegetables) are preferred over simple sugars and refined carbohydrates
• Fat intake should focus on heart-healthy sources (olive oil, fatty fish, avocados) to reduce the risk of cardiovascular disease, which is a common complication in dialysis patients
  • Saturated and trans fats should be limited
• Omega-3 fatty acids (EPA and DHA) may have anti-inflammatory and cardioprotective benefits for dialysis patients and can be obtained through fatty fish consumption or supplementation

Micronutrient Management

• Vitamin and mineral supplementation may be necessary to address deficiencies common in dialysis patients, such as vitamin D, vitamin B6, vitamin C, and zinc
  • Vitamin D deficiency is prevalent due to reduced synthesis in the skin and loss of vitamin D-binding protein during dialysis, and supplementation (calcitriol or analogs) is often required
  • Vitamin B6 (pyridoxine) deficiency can occur due to increased losses during dialysis and may require supplementation to prevent anemia and neuropathy
  • Vitamin C (ascorbic acid) levels may be low due to dietary restrictions and losses during dialysis, and supplementation can help improve iron absorption and reduce oxidative stress
  • Zinc deficiency is common and can impair immune function and wound healing, and supplementation may be necessary
• Iron supplementation is often required to prevent and treat anemia, which is common in dialysis patients due to increased blood loss and reduced erythropoietin production
  • Oral iron supplements (ferrous sulfate, ferrous gluconate) or intravenous iron (iron sucrose, ferric carboxymaltose) may be prescribed based on the severity of anemia and individual patient factors
• Phosphate binders (calcium acetate, sevelamer, lanthanum carbonate) are often prescribed to reduce phosphorus absorption from the diet and prevent hyperphosphatemia, which can lead to bone and cardiovascular complications

Fluid and Electrolyte Balance

• Maintaining fluid balance is crucial for dialysis patients to prevent complications such as hypertension, heart failure, and pulmonary edema
  • Interdialytic weight gain (IDWG) should be monitored closely and ideally limited to 2-3 kg between dialysis sessions
  • Sodium and fluid intake should be adjusted based on the patient's blood pressure, edema, and IDWG
• Potassium balance is important to prevent hyperkalemia, which can lead to cardiac arrhythmias and sudden death
  • Dietary potassium restriction and the use of potassium-binding resins (sodium polystyrene sulfonate) may be necessary
  • Dialysate potassium concentration can be adjusted to help manage serum potassium levels
• Calcium and phosphorus balance is essential for maintaining bone health and preventing vascular calcification
  • Dietary phosphorus restriction, the use of phosphate binders, and the adjustment of dialysate calcium concentration are strategies used to manage calcium and phosphorus levels
• Magnesium balance may also require attention, as both hypomagnesemia and hypermagnesemia can occur in dialysis patients and may contribute to cardiovascular and neuromuscular complications

Nutrition Assessment Techniques

• Anthropometric measurements, such as body weight, height, and body mass index (BMI), provide valuable information about the patient's overall nutritional status and changes over time
  • Ideal body weight (IBW) and adjusted body weight (ABW) may be used to determine nutrient requirements and dosing of medications
• Biochemical markers, such as serum albumin, prealbumin, and transferrin, can be used to assess protein status and identify patients at risk for PEW
  • Serum albumin levels <3.5 g/dL are associated with increased morbidity and mortality in dialysis patients
• Dietary intake assessment, including food records, 24-hour recalls, and food frequency questionnaires, can help identify nutrient deficiencies or excesses and guide dietary interventions
  • Protein catabolic rate (PCR) and normalized protein catabolic rate (nPCR) can be calculated from urea kinetic modeling to estimate protein intake and adequacy
• Subjective global assessment (SGA) is a comprehensive tool that combines medical history, physical examination, and functional status to classify patients as well-nourished, mildly to moderately malnourished, or severely malnourished
• Handgrip strength and other functional measures (sit-to-stand test, 6-minute walk test) can provide insights into the patient's muscle function and physical performance, which are important indicators of nutritional status

Dietary Interventions and Meal Planning

• Individualized meal plans should be developed based on the patient's nutritional needs, food preferences, cultural background, and socioeconomic status
  • Collaboration with a registered dietitian is essential for creating practical and sustainable meal plans
• Protein-controlled diets that emphasize high-quality protein sources and evenly distribute protein intake throughout the day can help optimize protein utilization and minimize waste product accumulation
  • Plant-based protein sources (legumes, nuts, seeds) can be incorporated to reduce the phosphorus and potassium load while providing other beneficial nutrients (fiber, antioxidants)
• Low-phosphorus and low-potassium food choices should be emphasized to help patients adhere to dietary restrictions
  • Encouraging the use of herbs, spices, and low-sodium seasonings can enhance the flavor of meals without adding excessive sodium, potassium, or phosphorus
• Nutrient-dense foods (fruits, vegetables, whole grains) should be prioritized to ensure adequate intake of essential vitamins and minerals while minimizing the overall dietary burden
• Meal timing and distribution should be optimized to prevent excessive catabolism and promote anabolism, particularly in relation to dialysis sessions
  • Providing a protein-rich snack or small meal after dialysis can help counteract the catabolic effects of the treatment
• Oral nutritional supplements (ONS) or enteral nutrition support may be necessary for patients who are unable to meet their nutritional needs through regular food intake alone
  • ONS can provide concentrated sources of protein, energy, and other essential nutrients in a convenient and palatable form
  • Enteral nutrition via a nasogastric tube or percutaneous endoscopic gastrostomy (PEG) may be required for patients with severe malnutrition or inability to consume adequate nutrition orally

Monitoring and Adjusting Nutritional Support

• Regular monitoring of nutritional status, including anthropometric measurements, biochemical markers, and dietary intake, is essential to assess the effectiveness of nutritional interventions and identify areas for improvement
  • Monthly or quarterly assessments may be appropriate, depending on the patient's stability and risk for malnutrition
• Adjustments to the nutritional care plan should be made based on changes in the patient's clinical status, laboratory values, and dietary adherence
  • For example, if a patient develops hyperkalemia, further restrictions in dietary potassium intake and the use of potassium-binding resins may be necessary
• Ongoing patient education and counseling are crucial to promote adherence to dietary recommendations and empower patients to make informed choices about their nutritional health
  • Providing practical tips for meal planning, grocery shopping, and dining out can help patients navigate the challenges of following a renal diet
• Collaboration among the interdisciplinary healthcare team, including nephrologists, registered dietitians, nurses, and social workers, is essential for providing comprehensive and coordinated care to address the complex nutritional needs of dialysis patients
• Monitoring and addressing psychosocial factors, such as depression, anxiety, and social support, is important as these can significantly impact a patient's ability to adhere to nutritional recommendations and overall quality of life
• Regularly assessing and adjusting dialysis prescription parameters, such as dialysate composition, treatment time, and frequency, can help optimize the removal of waste products and maintain fluid and electrolyte balance, which can have a significant impact on nutritional status