Table 2: Plasma ACTH gradient revealed by selective blood sampling from petrosal sinuses in the desmopressin stimulation test in patients with Cushing's disease and ectopic ACTH secretion.

ACTH gradient
Center/periphery
Cushing's disease
( )
Ectopic ACTH secretion
( )

Baseline levelAbove 2Below 2
After stimulation Above 3Below 2
Intersinus gradient Above 2.4Below 1.4