Sodium Polystyrene Sulfonate Used to Reduce the Potassium Content of a High-Protein Enteral Formula: A Quantitative Analysis

Background: Sodium polystyrene sulfonate (Kayexalate) commonly is used in treating hyperkalemia. As a cation exchange resin, it also can be used to reduce the potassium content of enteral nutrition formulas. This study evaluates the use of Kayexalate to reduce potassium in one high-protein enteral formula and describes the quantitative analysis of the product. Methods: Sodium polystyrene sulfonate and enteral formula were mixed into a slurry and allowed to settle, and then the supernatant was decanted off and tested as samples. Three sample concentrations were analyzed: a control not subjected to potassium reduction, 0.5 g of Kayexalate per mEq K⁺ sample, and a 1 g/mEq K⁺ sample. Of these samples, moisture, lipid, protein, carbohydrate, ash, and mineral content were obtained. Results: Compared with the control, the percentage decrease of potassium ranged from 25% to 36%, depending on the concentration of Kayexalate. A significant increase of 324% in sodium concentration was found in the 1.0 g/mEq K⁺ sample. Although there was no change in magnesium content, a slight increase in phosphorus, iron, and zinc was evident. Conclusions: The treatment of an enteral formula with sodium polystyrene sulfonate significantly increases its sodium content, with a modest decrease in potassium content. Clinicians using this method in clinical practice should be aware of the increase in sodium content.