The effects of resins added to the milk of children suffering from chronic kidney disease: a clinical relevance to control potassium and phosphate levels?

Abstract

Background: In infants with chronic kidney disease (CKD), the management of nutrition and growth is highly challenging, particularly compared to older children. Management of hyperkalemia and hyperphosphatemia is difficult, and incorporating potassium and phosphate binders directly in formulas could be beneficial, as it avoids direct ingestion of resins by infants.

Materials and methods: We conducted a study using Gallia® standard first-stage infant formula and Pregestimil®. We added either carbonate sevelamer (Renvela®, 200, 400 or 800 mg) or polystyrene sulfonate (Resikali®, 2000, 4000 or 8000 mg) to 90 ml of formula. Additionally, we evaluated the combined use of the resins with Gallia® by adding in 90 mL 200 mg/2000 mg, 400 mg/4000 mg, and 200 mg/4000 mg of Renvela® and Resikali®, respectively. The Milk was decanted for 10 minutes, and the resulting supernatants were weighted and analyzed for osmolality and pH. Sodium, potassium, chlore, bicarbonate, magnesium, glucose, calcium, phosphate, protein, cholesterol, triglycerides, iron, folate, vitamin B12 levels were measured after centrifugation.

Results: With polystyrene sulfonate, potassium levels in milk decreased in a dose-dependent manner, by 36%, 52% and 68%, respectively. Polystyrene sulfonate also reduced magnesium levels and increased both calcium concentration (from 9.7 to 21 mmol/L) and osmolality (from 359 to 423 mOsm/kg). No significant effect on phosphate was observed. Sevelamer decreased both calcium and phosphate concentrations in a dose-dependent manner, by 14%, 26% and 29%, and by 24%, 36% and 40%, respectively. Sevelamer also increased pH from 6.9 to 9.1, and decreased folate levels by 32%, 66% and 81% respectively, from 465 to 88 mmol/L. The combined use of sevelamer and polystyrene sulfonate results in decreased levels of potassium (by 45%, 59% and 59%, respectively), phosphate (by 38%, 39% and 36%, respectively), and folate, albeit with a slighter increase in pH. Osmolality remained unchanged and no other relevant differences were observed.

Conclusion: Pretreating formulas with resins is a reproducible and straightforward method when specific diets for CKD are unavailable. However, it is important to keep in mind that resins may impact the overall composition (osmolality) and the concentration of other nutrients (folates).