Effectiveness of Sodium Polystyrene Sulfonate for Short-Term Treatment of Hyperkalemia

Background: Sodium polystyrene sulfonate (SPS) is a potassium-binding resin that is commonly used to treat mild hyperkalemia. However, there is limited evidence supporting its effectiveness in the short-term management of hyperkalemia.

Objective: To determine whether SPS is effective in reducing serum potassium in general medical patients after a single oral dose.

Methods: A retrospective observational study was conducted for patients admitted to the internal medicine service of a tertiary care hospital between January 2011 and May 2012 with documentation of a serum potassium level between 5.0 and 5.9 mmol/L during the hospital stay. Patients eligible for inclusion were adults without chronic or acute renal failure or recent changes in medication or diet that would affect serum potassium level. Propensity score matching was performed to minimize differences between the control group (no treatment) and the treatment group (treatment with oral SPS). Follow-up serum potassium levels (at 6-24 h) were compared with index potassium levels.

Results: A total of 138 patients met the inclusion criteria, 72 in the control group and 66 in the treatment group. For most patients in the treatment group, the dose was 15 or 30 g of SPS orally. The difference between the control and treatment groups in terms of mean change in serum potassium at 6 to 24 h after the index potassium measurement was statistically significant (by paired t test) in both an unmatched analysis (-0.41 ± 0.50 and -0.58 ± 0.39 mmol/L, respectively; p = 0.039) and a matched analysis (-0.44 ± 0.29 and -0.58 ± 0.39 mmol/L, respectively; p = 0.026). No difference was observed in terms of mean change in serum potassium between patients who received 15 and 30 g of SPS (-0.51 ± 0.38 and -0.66 ± 0.40 mmol/L, respectively; p = 0.13).

Conclusions: In patients with mild hyperkalemia, oral SPS therapy reduced serum potassium by 0.14 mmol/L more than control. Although this difference was statistically significant, the small treatment effect observed in this study may not be clinically important. Furthermore, the cost and potential adverse effects of treatment suggest that routine use of SPS may be inappropriate for patients with mild hyperkalemia. Prospective randomized controlled trials would help in further evaluating the effectiveness and safety of SPS.