A 58-year-old woman with a 10-year history of hypertension on amlodipine monotherapy (BP currently 142/88 mmHg) is found to have a plasma renin activity of 0.2 ng/mL/hr (normal 0.5–1.6) and aldosterone of 22 ng/dL (normal <15). Serum potassium is 3.5 mEq/L and sodium is 145 mEq/L. She denies licorice use and is not on diuretics. Saline suppression test shows aldosterone of 8 ng/dL. What is the most appropriate next step in management?