Endocrine Abstracts

Background: BIPSS is the most reliable procedure for differentiation Cushing’s disease (CD) from ectopic ACTH secretion (EAS).

Aim: To determine the comparability of 8-mg dexamethasone supression test (BDST) and BIPSS for differential diagnosis ACTH-dependent hypercortisolism.

Materials and methods: We present 6 patients with confirmed ACTH-dependent hypercortisolism. All of them BDST (8 mg dexamethasone at 2300 h) and BIPSS (with a cut-off central/peripheral ACTH-ratio of 2.0 or more) have been made. Also MRI and CT scan were performed.

Results: In 3 of 6 cases plasma cortisol suppression was more than 50% after BDST and pituitary adenoma was seen in MRI. Only in 1 of this 3 cases of CD a center/periphery-ACTH gradient was more than 2. Interestingly that the gradient was on the opposite to the location of pituitary microadenoma side. It was probably because of left sinus (on the side of adenoma location) contraction during catheterization. In other 2 of this 3 cases of CD a center/periphery-ACTH gradient was <2: in 1 case it was sinus anomaly (the absence of the right petrosal sinus), in other – may be attributed to technical factors.

In 1 of 6 case plasma cortisol suppression was 53.6% in BDST and no adenoma on MRI. However, a center\periphery-ACTH gradient was 15, 2. So CD was diagnosed.

In 2 of 6 cases plasma cortisol suppression in BDST were 3.5 and 54% respectively. MRI and CT show no abnormalities. After BIPSS the center/periphery-ACTH gradient was 1.06 and 1.27 respectively. EAS was diagnosed.

Conclusion: It should take into account data from all possible exam for the differential diagnosis of different forms of ACTH-dependent hypercortisolism.