Risks and Benefits of Sodium Polystyrene Sulfonate for Hyperkalemia in Patients on Maintenance Hemodialysis

BACKGROUND: Concerns about sodium overload when using sodium polystyrene sulfonate (Na-resin) as an ion-exchange resin for the treatment of hyperkalemia led our institution to gradually shift to the use of calcium polystyrene sulfonate (Ca-resin). However, as serum potassium levels were insufficiently controlled and patients experienced constipation, we returned to using Na-resin and observed better results than previously. OBJECTIVE: As few papers have examined the potassium adsorption ability of Ca-resin compared with Na-resin, we investigated this issue within our institution. METHODS: We studied potassium adsorption in patients who switched from Ca-resin to an equivalent amount of Na-resin (change group). We also investigated the incidence of sodium loading with Na-resin, including in patients newly commencing Na-resin treatment (new start group). RESULTS: Mean (± standard deviation) serum potassium levels decreased significantly, from 5.5 ± 0.6 to 4.9 ± 0.6 mEq/l in the change group and from 5.9 ± 0.4 to 4.7 ± 0.6 mEq/l in the new start group. No changes were observed in blood pressure, weight gain or serum sodium levels in the change group, but serum sodium levels in the new start group increased significantly, from 137.4 ± 2.3 to 139.0 ± 2.5 mEq/l, although they remained within the normal range. CONCLUSIONS: Our results indicate that Na-resin exhibited an advantage in treating hyperkalemia when used in small amounts. However, when prescribing an ion-exchange resin at a higher dose, physicians should select the type and amount of resin according to the sodium and/or calcium load in each case.