Inclusion Criteria:  Renal transplant recipients, at least 3 weeks after transplantation, who receive Tacrolimus as part of their immunosuppressive therapy, with stabile tacrolimus dose and trough tacrolimus concentration. Recipients 18 years of age or older. Hyperkalemia (K>5 and <6,0) Signed informed consent.  Exclusion Criteria:  Concomitant treatment with: diltiazem, verapamil, fenytoin, carbamazapin, fluconazole, ketoconazole, vorikonazole, erythromycin, clarithromycin, resonium-calcium, and/or sodium zirconium cyclosilicate. Constipation, defined as fewer than three bowel movements per week. Hypomagnesemia less than 0.6 mmol/L. Serum potassium level of greater than 6.0 mEq/L. Increased immunologic risk patient (DSA, ABO-incompatible transplant). Pregnancy or suspected pregnancy (pregnancy is excluded at time of transplantation by measuring HCG, kidney transplanted patients should not become pregnant before at least one year after transplant, and no transplanted patient has ever become pregnant during the first weeks after transplantation. They are all informed regarding different types of contraception). Fertile women will be tested for pregnancy before inclusion. Hypersensitivity/allergy to patiromer. Other serious medical or psychiatric condition likely to interfere with participation.