A 38-year-old man with panhypopituitarism is evaluated for worsening fatigue and weight gain over the past 3 months. He is sleeping 9 hours each night, but he feels tired during the day and has decreased his usual exercise level. He has morning erections but reports low libido and occasional erectile dysfunction during intercourse. He wakes once during the night to urinate and drink water. He estimates that he urinates 5 to 8 times during the day, which is unchanged.
Medical history is significant for transsphenoidal resection of a craniopharyngioma at age 18 years. He has required anterior pituitary hormone replacement and desmopressin since that time. Medications are desmopressin, hydrocortisone, levothyroxine, somatropin, and testosterone enanthate.
On physical examination, temperature is 37.0 °C (98.6 °F), blood pressure is 118/64 mm Hg, pulse rate is 74/min, and respiration rate is 14/min. No orthostatic changes are noted. BMI is 24. There are no facial changes suggestive of acromegaly or Cushing syndrome. The thyroid is normal without goiter or nodules. Hair distribution and skin turgor are normal. There is no gynecomastia or striae. Normal penis and testicular volume are noted. Visual fields are intact on neurologic examination.
Sodium | 138 mEq/L (138 mmol/L) |
Insulin-like growth factor 1 | Normal |
Prolactin | 18 ng/mL (18 µg/L) |
Thyroid-stimulating hormone | 0.8 µU/mL (0.8 mU/L) |
Thyroxine (T4), free | 0.7 ng/dL (9.0 pmol/L) |
Testosterone (11 days after injection) | 482 ng/dL (16.7 nmol/L) |
Follow-up MRIs show no residual tumor.
Which of the following is the most appropriate management?