The Investigator hypothesize that a single dose of patiromer will lower serum potassium levels in less than 6hrs. Since a dosage of 30g/day for a period of 4 weeks has been studied in at least two multicenter randomized controlled trials, the Investigator further hypothesize that a single dose of 25.2g of patiromer will be well tolerated in hyperkalemic patients in the Emergency Department setting. The FDA approved dosage of 25.2g is appropriate for this study because the research staff will enroll patients with moderate (K greater than 6 mEq/L) to severe hyperkalemia, and the higher dosage has typically been used in this population for more effective control.