Background: Hyperkalemia is prevalent in end-stage renal disease patients, being involved in life-threatening arrhythmias. Although polystyrene sulfonate (PS) is commonly used for the treatment of hyperkalemia, direct comparison of effects between calcium and sodium PS (CPS and SPS) on mineral and bone metabolism has not yet been studied.
Methods: In a randomized and crossover design, 20 pre-dialysis patients with hyperkalemia (>5 mmol/l) received either oral CPS or SPS therapy for 4 weeks.
Results: After 4-week treatments, there was no significant difference of changes in serum potassium (K) from the baseline (ΔK) between the two groups. However, SPS significantly decreased serum calcium (Ca) and magnesium (Mg) and increased intact parathyroid hormone (iPTH) values, whereas CPS reduced iPTH. ΔiPTH was inversely correlated with ΔCa and ΔMg (r = -0.53 and r = -0.50, respectively). Furthermore, sodium (Na) and atrial natriuretic peptide (ANP) levels were significantly elevated in patients with SPS, but not with CPS, whereas ΔNa and ΔANP were significantly correlated with each other in all the patients. We also found that ΔNa and Δ(Na to chloride ratio) were positively correlated with ΔHCO3-. In artificial colon fluid, CPS increased Ca and decreased Na. Furthermore, SPS greatly reduced K, Mg, and NH3.
Conclusion: Compared with SPS, CPS may be safer for the treatment of hyperkalemia in pre-dialysis patients, because it did not induce hyperparathyroidism or volume overload.
Keywords: Calcium; Chronic kidney disease; Hyperkalemia; Potassium; Secondary hyperparathyroidism; Sodium.