A 55 year-old man comes to your office with complaints of gradual breast enlargement over the past 3 months. He has mild tenderness in both breasts, more pronounced on the left side. He also describes psychological discomfort about his appearance, explaining the feelings of embarrassment. His medical history is significant for hypertension, chronic heart failure (NYHA Class II), and type 2 diabetes mellitus. His current medications include spironolactone, metoprolol, metformin, furosemide and aspirin. He does not consume alcohol excessively and denies use of anabolic steroids or recreational drugs. He has no family history of breast cancer or hormonal disorders. On physical examination, you notice a well-appearing male. His blood pressure is 128/80 mm Hg and heart rate is 72 bpm. He has enlarged breasts, but no discharge or lumps. There is mild tenderness on palpation of both breasts. There is no nipple retraction or discharge. Which of his current medications most likely caused his breast condition?
