A 24-year-old man presents with a two-year history of fatigue, malaise, daytime sleepiness, and poor appetite. No other symptoms are present. He sought medical attention three times over this period. As no physical signs were found, and all basic investigations including complete blood counts, electrolyte counts, and renal and liver profiles were normal, his symptoms were considered to be either psychogenic or factitious. He does not smoke, drinks around 5 to 7 units of alcohol per week, and "occasionally" uses marijuana. He denies using "hard" drugs. A electrolyte assay reveals a serum sodium of 135 mEq/L (normal: 135-145). A complete blood count, liver profile, and renal profile are all within normal parameters.
Random GH: 3.6 ng/mL (0 - 5) ACTH: 7.3 pg/mL (9 - 52) 8AM cortisol: 2.76 µg/dL (7 - 28) T3: 64.4 ng/dL (75 - 200) Free T4: 0.646 ng/dL (0.8 - 1.8) TSH: 0.325 IU/mL (0.4 - 4.5) Testosterone: 0.09 ng/mL (1.5 - 7.0) FSH: 0.27 mIU/mL (4.7 - 21.5) LH: 0.42 mIU/mL (5 - 25) Prolactin: 41.6 ng/mL (2 - 18)
There is a 0.6 x 0.5 cm lesion in the parasellar region, compressing the pituitary stalk. The tumor is isointense to grey matter in both T1 and T2 images. There is no evidence of cavernous sinus invasion. The posterior lobe of the pituitary gland shows normal signal intensity.
Serum cortisol: 3.16 µg/dL (normal: >18), 45 minutes after injection of synthetic ACTH.
The skeletal survey appears normal.