A 40-Year-Old Man Comes to the Physician for the Evaluation

A 40-year-old man comes to the physician for the evaluation of episodic headaches for 5 months. The headaches involve both temples and are 4/10 in intensity. The patient has been taking acetaminophen, but the headaches did not subside. He has also had visual disturbances, including double vision. He has no nausea, temperature intolerance, or weight changes. The patient does not smoke. He drinks 2-3 beers on weekends. He appears pale. His temperature is 37°C (98.6°F) , pulse is 75/min, and blood pressure 125/80 mm Hg. Ophthalmologic examination shows impaired peripheral vision bilaterally. An MRI scan of the head with contrast shows a 16 × 11 × 9 mm intrasellar mass. Which of the following pituitary hormones is most likely elevated in this patient?

A) ACTH
B) Growth hormone
C) Prolactin
D) Thyrotropin
E) Vasopressin