A 35-Year-Old Man Comes to the Office Due to Recent

A 35-year-old man comes to the office due to recent erectile dysfunction. He has no medical conditions and takes no medications. He states that he has a loss of libido and chronic headaches for 3 months.  He does not use tobacco, alcohol, or illicit drugs.  Vital signs are normal.  The examination is notable for peripheral vision loss, bilateral gynecomastia, and soft testes without masses.  Laboratory evaluation shows normal serum prolactin, normal B-hCG, low serum LH, and low serum testosterone.  Which of the following is the most likely mechanism for this patient's gynecomastia?

A) Decreased systemic clearance of estrogen
B) Defective androgen receptor function
C) Enzymatic defect in the testosterone biosynthetic pathway
D) Excessive estrogen production in the testes
E) Persistent aromatization of adrenal estrogen precursors