Enteral nutrition in dialysis and kidney disease

Goals of nutritional intervention in CKD and dialysis

Principles

• Enteral feedings are frequently necessary to ensure adequate nutrient intake
  • Administered by enteral feeding tube (e.g., NGT, NJT, GT, GJT), by mouth, or as a combination
• Individualized
  • May provide sole or partial source of nutritional needs
  • Avoid excessive intake of any single nutrient, especially vitamin A (particularly in retinol form)
    • Nutrients and minerals can accumulate in CKD and cause toxicity (e.g., hypervitaminosis A)
  • Use of modular components (carbohydrate [CHO], fat, protein) to increase caloric density or protein provision when necessary
• PD and HD treated the same in terms of calorie composition

Kidney formulas

Similac® PM 60/40

• Made by Abbott
• The only kidney-specific infant formula
• Suitable for birth-12 months
  • Infant formula has higher percentage of fat (similar to that of breastmilk)
  • Can be used up to 14 months if a patient would benefit from additional catch-up growth
• Powder (unflavored), standard mixing 20 kcal/oz
  • Can be used as a fortifier for EBM
  • Can be concentrated up to 30 kcal/oz
• Suitable for oral and tube feeding use
• Suitable as sole-source of nutrition for an infant
• Lower in calcium, phosphorus, iron, sodium and potassium compared to standard pediatric formulas
  • Designed to approximate the mineral contents of breastmilk
  • Infants often still need decanting for potassium, but often require phosphorus supplementation and iron supplementation

Renastart™

• Made by Vitaflo, a Nestlé subsidiary
• Formulated for pediatric patients ≥1 year old
  • Has been shown to be safe in case studies as a fortifier for expressed breastmilk (EBM), even in infants (<1 year old)
    • Can be alternative for Similac 60/40 or used for patients who have significant hyperkalemia issues despite decanting
• Powder (unflavored), standard mixing 30 kcal/oz
  • Can be concentrated up to 2 kcal/mL (60 kcal/oz)
    • Increased rates of feeding intolerance when on highly concentrated
  • Usually dosed based on grams or scoops
• Suitable for oral and tube feeding use, but usually used in tube feeding
  • Unflavored: does not taste great but can be mixed in with other formulas or food products (e.g., used in baking)
• Not suitable as a sole-source of nutrition
  • Used for supplemental feeds, added to food products, or as an additional ingredient in part of a feeding recipe with a more nutritionally complete formula with greater micronutrient content
• Lower in protein, calcium, chloride, potassium, phosphorus and vitamin A compared to standard pediatric formulas

Renal Support 1.8

• Made by Kate Farms
• Ready-to-feed (RTF) liquid, 54 kcal/oz (1.8 kcal/mL)
• Technically an adult formula
  • Designed for adult dialysis patients (higher in protein)
  • Can be used in pediatric patients ≥1 year old; however, typically used in older adolescent patients due to high protein content
• Suitable for oral and tube feeding use
• Suitable as a sole-source of nutrition
• Lower in potassium, phosphorus, and vitamin A compared to standard formulas
• The lower vitamin A makes it an attractive alternative to Nepro
  • Relatively new product so many not be available on hospital formularies

Suplena®

• Made by Abbott
• Ready-to-feed (RTF) liquid (vanilla), 54 kcal/oz (1.8 kcal/mL)
  • Can be used within 48 hours of opening as long as it is refrigerated
  • Vanilla flavor is used at LPCH as that is the best flavor for potassium and phosphorus content
• Technically an adult formula
  • Designed for adult non-dialysis CKD patients
    • Lower in protein compared to Nepro, which tends to be a bit too high in protein for our pediatric patients
    • Can be used in pediatric patients ≥1 year old
• Suitable for oral and tube feeding use
• Suitable as a sole-source of nutrition
  • Rare to be 100% of nutritional needs, typically because the volume required to meet their nutritional needs would exceed their maximum allowable vitamin A, so it is usually paired with additional formulas or modulars
• Lower in potassium and phosphorus compared to standard formulas

Nepro®

• Made by Abbott
• Ready-to-feed (RTF) liquid, 54 kcal/oz (1.8 kcal/mL)
  • Vanilla flavor is used at LPCH as that is the best flavor for potassium and phosphorus content
• Technically an adult formula
  • Designed for adult dialysis patients (higher in protein)
  • Can be used in pediatric patients ≥1 year old, however typically use in older/adolescent patients (≥12 years)
• Suitable for oral and tube feeding use
• Suitable as a sole-source of nutrition
• Lower in potassium and phosphorus compared to standard formulas

Renastep™

• Made by Vitaflo, a Nestlé subsidiary
• Formulated for pediatrics ≥1 year old
• Ready-to-feed (RTF), vanilla flavored, 60 kcal/oz (2 kcal/mL)
• Suitable for oral and tube feeding use
• Not suitable as a sole-source of nutrition
• Lower in potassium, calcium, chloride, phosphorus, and vitamin A compared to standard pediatric formulas
  • Similar to Renalcal but has more DHA in it
• Relatively new product so many not be available on hospital formularies

Modular formulas (additives)

Duocal®

• Made by Nutricia
  • High calorie powder
  • Only contains CHO and fat, no protein
  • Safe for patients with cow’s milk
• Trace amounts of micronutrients but rarely causes issues unless given in excessive amounts
• Suitable for oral and tube feeding use
• Not suitable as a sole-source of nutrition

Beneprotein®

• Made by Nestlé
• Intact, whey-based protein powder
• Suitable for oral and tube feeding use
• Unflavored product
• Tends to form a chunky texture, but can mix well with a blender
• Lower in protein per scoop than comparable products used in adults
  • 1 scoop (1.5 Tbsp) is 7 grams of powder by weight but contains 6 grams of protein
    • Because of the potential for confusion, most dietitians will prescribe Beneprotein in terms of scoops or tablespoons rather than by weight.
• Not suitable as a sole-source of nutrition
• Used for a child who needs additional protein and who does not have milk protein allergy

Complete Amino Acid Mix

• Made by Nutricia
• Amino acid (AA)-based protein powder
• Safe for patients with cow’s milk allergy or multiple food allergies
• Suitable for oral and tube feeding
• Not suitable as a sole-source of nutrition

MCT Oil®

• Made by Nestlé
• ~7.7 kcal/mL
• Unflavored
• For patients who are unable to digest or absorb conventional (long chain) fats
  • MCTs are more readily hydrolyzed and absorbed than long chain fats
  • MCTs are absorbed directly into the portal circulation and do not require the bile salts for emulsification
• Helpful for patients with fat malabsorption who struggle with other modular formulas like duocal
• Suitable for oral and tube feeding use
• Usually given as a separate bolus
• Not suitable as sole source of nutrition
• Administered alone, not mixed with formula
  • Hydrophobic and does not contain an emulsifier: does not interact well with water
    • Will float to the top of a formula batch, so is usually given on its own
    • Does tend to stick to tubing, so may require a water flush to get through the tube

Liquigen® (by Nutricia)

• Emulsified for easier mixing
  • 50% MCT/50% water
  • Can be mixed with formula or provided alone
  • May not be the best choice for someone who is very fluid restricted
• ~4.5 kcal/mL
  • Lower caloric density than MCT Oil, but doesn’t require a flush to get through the tube, so may end up being lower volume
• Unflavored
  • Not unpalatable
• For patients who are unable to digest or absorb conventional fats
  • MCTs are more readily hydrolyzed and absorbed than long chain fats
  • MCTs are absorbed directly into the portal circulation and do not require bile salts for emulsification
• Suitable for oral and tube feeding use
• Not suitable as a sole source of nutrition

Microlipid®

• Made by Nestlé
• Emulsified for easier mixing
  • 50% MCT/50% water
  • Can be mixed with formula or provided alone
• Microlipid has long chains
• Avoided in chylothorax but either is a fine choice for the kidney population
• For patients who are unable to digest or absorb conventional fats
  • MCTs are more readily hydrolyzed and absorbed than long chain fats
  • MCTs are absorbed directly into the portal circulation and do not require bile salts for emulsification
• Suitable for oral and tube feeding use
• Not suitable as a sole source of nutrition

Decanting

• Decanting is the action of using a medication to remove a specific nutrient from a formula (or breastmilk)
• The two medications commonly used to do this are:
  • Sodium polystyrene sulfonate (Kayexalate®)
    • Used to decrease the amount of potassium from formula
  • Sevelamer (Renvela®)
    • Used to decrease the amount of phosphorus in formula
• When added to formula, these medications act as a “sponge” to bind these nutrients and form a solid precipitate
• Other nutrients are affected by decanting, but the impact is difficult to quantify
  tip

  If a patient requires decanting for both potassium and phosphorus, always decant with with the potassium binder first and the phosphorus binder second

Potassium binder used in decanting formula

• Sodium polystyrene sulfonate (SPS, Kayexalate®)
  • Mechanism of action
  • Binds potassium ions in the GI tract and prevents intestinal absorption (sodium exchange)
  • Comes in powder or liquid form
    • Powder form is preferred
      • Liquid does not form as obvious a precipitate (more of a slurry), making it hard to pour off
        • It is still safe to ingest, but may clog tubes or enzyme cartriges
      • Liquid form increases aluminum content in feeds and contains sorbitol which can cause gastrointestinal side effects
  • Typical doses
    • 4 level teaspoons = 15 grams
    • 60 mL = 15 grams
  • Can cause diarrhea or hypernatremia

Phosphorus binders used in decanting formula

Non-calcium based

• Sevelamer (e.g., Renvela®)
• Use powder form only (pills will not disintegrate into the formula)
• Typical doses: 0.8 g packet, 2.4 g packet
  • Recommend starting on the low end of dosing range and titrating up to effect
• Added to formula with instructions to pour off specific volume of formula for use
  • Extra formula is built into the recipe to account for the loss that comes from decanting

Calcium-based

• Calcium carbonate (CaCO₃)
  • Use liquid form only
    • Typical dose: 5 mL liquid = 1250 mg (500 mg elemental Ca²⁺)
  • 40% elemental calcium (100 mg elemental Ca²⁺ per mL)
  • Can cause/contribute to hypercalcemia
  • Added to formula with no instructions to pour off specific volume of formula for use
• Calcium acetate (Ca(C₂H₃O₂)₂)
  • Use liquid form only (Phoslyra®)
  • Typical dose: 5 mL liquid = 667 mg (169 mg elemental Ca²⁺)
  • 25.3% elemental calcium (33.75 mg elemental Ca²⁺ per mL)
  • Added to formula with no instructions to pour off specific volume of formula to use
    • Does not cause issues with clogging tube

Modifying formula recipes for decanting

• Extra 100 mL of extra total volume of formula added per decanting agent
• Typically, only decant formula ingredients that largely contribute to the potassium and/or phosphorus load to avoid waste and complicated recipes
  • For example, not necessary to decant water or most modular formulas (additives)

Decanting process

• Supplies: prescribed formula(s) and recipe
• Prescribed decanting medication(s)
• Two large plastic containers
• A spoon if the container does not have a cap or liquid
• Refrigerator or cooler