Clinically significant hyperkalemia, defined as potassium ≥ 6.0 mEq/L can be a life-threatening, and urgent lowering of serum potassium is needed to prevent life-threatening arrhythmias. There are many potential causes of hyperkalemia including acute or chronic kidney disease, medications (e.g. ACE-inhibitors), and rhabdomyolysis among other causes.
Kaur, Rajandeep PharmD and Linn, Dustin D PharmD, BCPS, BCCCP, "Efficacy of Sodium Polystyrene Sulfonate in Hyperkalemia" (2019). Pharmacy. 38.