A 54 year-old male is admitted to the hospital for an abdominal surgery. His current medications include digoxin, enalapril, ibuprofen and ketoconazole. He is on heparin for DVT prophylaxis. His laboratory tests reveal the following: random, non-fasting, serum glucose: 357 mg/dl (normal fasting glucose: 70 – 100 mg/dL; Random, non-fasting: <140 mg/dL) serum potassium 6.2 mEq/L (normal serum potassium: 3.5 - 5.0 mEq/L) You reviewed his medical records as you investigated the etiology of his hyperkalemia. Which of the following is a cause of hyperkalemia, because it inhibits potassium excretion from the body?
