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Decanting in dialysis and kidney disease

Decanting enteral formulas for use in pediatric patients on dialysis and children with acute or chronic kidney disease

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 the potassium binder first and the phosphorus binder second

Potassium binder used in decanting formula

  • Sodium polystyrene sulfonate (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 separate the formula from the precipitate
          • It is not harmful if the precipitate is ingested, though may cause issues with feeding tubes or enzymatic cartridges
        • 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

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

example

Patient is on 700 mL PediaSure® Enteral 1.0 Cal with Fiber and needs to start decanting due to
  • Step 1: In a clean container, measure out 800 mL of PediaSure® Enteral 1.0 Cal with Fiber
  • Step 2: Add 15 grams of Kayexalate® to the formula
  • Step 3: If you are using an open top container, use a spoon to stir the formula mixture well for at least 1 minute

  • Step 4: Cover the formula mixture with a lid or piece of saran wrap and refrigerate for 30-60 micronutrients

    • Minimal difference between 30 and 60 minutes
    • OK to do longer than 60 minutes but this is not necessary
    • This will allow for the Kayexalate® medication to bind with the potassium and settle at the bottom of the container

  • Step 5: Pour off 700 mL decanted formula into the second clean container and save for later use

    • Optional: you may use a strainer to help prevent the precipitate from spilling over in the decanted formula
    • It is common (and harmless) to have a little bit of precipitate in the formula that will be given to the patient
    • Throw away the solid precipitate that is sitting on the bottom of the container