Potassium Reduction Associated with Lactulose and Sodium Polystyrene Sulfonate Use in Hospitalized Patients with Hyperkalemia: A Real-World Observational Study

Background Hyperkalemia is a common electrolyte disorder in hospitalized patients. Sodium polystyrene sulfonate (SPS) is frequently used to increase gastrointestinal potassium loss. The objective of this study was to describe and compare the potassium reduction associated with lactulose, SPS alone, and combined lactulose-SPS use in hospitalized patients with hyperkalemia. Materials and Methods We performed a post-hoc analysis of adult hospitalized patients with hyperkalemia (potassium concentration [K + ] ≥5.5 mmol/L) treated with either lactulose alone (L), SPS alone (S), or lactulose plus SPS (LS) from 01 January to 31 December 2019. Patients undergoing dialysis were excluded. We compared the reduction in potassium concentration ([K + ]) among these three groups over the first 24 h and 2-7 days. Results A total of 134 patients were included, with 30% in the L-group, 53% in the S-group, and 17% in the LS-group. There were no differences in age, sex, or comorbidities among the groups; however, all patients in the LS-group had kidney dysfunction ( p < 0.001). Baseline [K + ] was highest in the LS-group (6.0 mmol/L (L) vs. 6.4 mmol/L (S) vs. 7.2 mmol/L (LS), p = 0.003). There were no differences in serum potassium concentrations at 24 h ( p = 0.146) or at days 2-7 ( p = 0.610). However, the absolute reduction in serum potassium over days 2-7 was greater in the LS group compared with the L group (-1.75 mmol/L vs -0.9 mmol/L; p = 0.038). Sensitivity analyses and multilinear regression consistently showed that potassium reduction was primarily associated with baseline [K + ]. Conclusion Among hospitalized patients with hyperkalemia, the combination of lactulose and SPS was associated with larger reductions in serum potassium at days 2-7, although causal inference cannot be made.