Pretreatment of formula or expressed breast milk with sodium polystyrene sulfonate (Kayexalate(®)) as a treatment for hyperkalemia in infants with acute or chronic renal insufficiency.

OBJECTIVE: To evaluate the effect on serum potassium of treating infant formula or expressed breast milk (EBM) with sodium polystyrene sulfonate (SPS) before patient consumption.

DESIGN AND SETTING: Retrospective cohort study of patients at Seattle Children's Hospital who received SPS-treated formula or EBM.

SUBJECTS AND INTERVENTION: Thirteen patients less than 2 years of age with a diagnosis of hyperkalemia and acute kidney injury or chronic kidney disease that had received formula or EBM pretreated with SPS between September 2009 and May 2012 were identified. Hyperkalemia was defined as a serum potassium concentration greater than 5.5 mEq/L.

MAIN OUTCOME MEASURE: The primary endpoint was the mean change in serum potassium 48 hours after receiving pretreated formula or EBM. Serum potassium levels before and after patient consumption were averaged and compared using a paired t test.

RESULTS: Pretreatment of formula or EBM with SPS resulted in a 24% decrease in serum potassium levels (6.3 mEq/L to 4.8 mEq/L; P < .0001). There was a significant difference in before and after calcium and creatinine levels (P < .05), and no significant differences in blood urea nitrogen, sodium, magnesium, phosphorus, chloride, or bicarbonate levels.

CONCLUSION: Pretreatment of formula or EBM with SPS before consumption is an effective treatment for hyperkalemia in infants. Caution needs to be taken in patients who have sodium restrictions because the exchange for potassium produces a sodium-rich formula.