Step 1: View clinicals

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.

Step 2: Order all relevant investigations

Endocrine profile

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)

MRI brain

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.

ACTH stimulation test

Serum cortisol: 3.16 µg/dL (normal: >18), 45 minutes after injection of synthetic ACTH.

Skeletal survey

The skeletal survey appears normal.

Step 3: Select appropriate management

Start hydrocortisone first
Start levothyroxine first
Growth hormone replacement
Neurosurgical referral

Score: ★★☆