24-h urinary free cortisol (?

A 48-year-old woman presented with a 2-year history of weight gain, easy bruising and mood disturbance.

Investigations:

fasting plasma glucose6.9 mmol/L (3.0C6.0)

low-dose dexamethasone suppression test (2 mg/day for 48 h):

serum cortisol200 nmol/L (<50)

24-h urinary free cortisol (?3)670, 400 and 300 nmol (55C250)

plasma adrenocorticotropic hormone (09.00 h)25.0 pmol/L (3.3C15.4)

MR scan of pituitarynormal

What test is most likely to give a definitive diagnosis?
A . corticotropin-releasing hormone test
B . CT scan of chest
C . high-dose dexamethasone suppression text (8 mg/day for 48 h)
D . octreotide scan
E . petrosal sinus sampling

View Answer

Answer: E