A 45-year-old man who underwent transsphenoidal resection of a clinically non-functioning pituitary macroadenoma 6 months ago returns for endocrine follow-up. He says that his stamina and overall well-being have diminished since he underwent pituitary surgery. He has gained 10 lb postoperatively. He reports no headache, visual symptoms, nausea, constipation, dizziness, polyuria, low libido, erectile dysfunction, edema. His past medical history is otherwise significant for gastro-esophageal reflux disease but no diabetes mellitus or malignancy. His only medication includes omeprazole 20 mg daily. On examination, he appears well. His blood pressure is 125/84 mm Hg and his pulse is 78 / min. His weight is 210 lb with a height of 5’7” (body mass index: 32.7 kg/m2). There are no features of acromegaly or Cushing’s on exam. Visual fields are full on confrontation testing. There is no goiter. Muscle strength is intact.
A recent postoperative MRI examination shows anticipated postoperative findings and a small tumor remnant (measuring 3 mm by 3 mm by 4 mm) present in the right cavernous sinus.
Recent laboratory tests include: prolactin: 10 ng/ml (normal, 0 to 23); IGF-I: 95 ng/ml (normal, 50 to 320); TSH: 2.5 mcu/ml (normal, 0.4 to 4.5); free T4: 1.2 ng/dl (normal, 0.8 to 1.8); ACTH: 22 pg/ml (normal, 5 to 60); morning cortisol: 18.2 mcg/dl; LH: 2.1 U/l (normal, 1 to 8); FSH: 3.4 U/l (normal, 1 to 8); total testosterone: 420 ng/dl (normal, 250 to 800).
He undergoes a glucagon stimulation test, during which his growth hormone reaches a peak level of 2.1 ng/ml.