RELATIONSHIP BETWEEN ADRENAL-CORTEX PATHOLOGY IN CUSHINGS-SYNDROME AND ITS RESPONSE TO THE DEXAMETHASONE SUPPRESSION TEST

Cushing's syndrome is a severely disabling condition which can cause d eath if left untreated. Endogenous Cushing's syndrome can be ACTH-depe ndent or ACTH-independent. The ACTH-dependent type is more common and is usually caused by diffuse hyperplasia on the adrenal cortex. This s tudy investigated the response to low- and high-dose dexamethasone sup pression testing of 30 adrenalectomized patients with Cushing's syndro me, average age 37.3 +/- 9.7 years. Twenty-four (79.3%) patients were female, and six (20.7%) were male. Bilateral adrenalectomy was perform ed in 14 (48.2%) patients and unilateral adrenalectomy (nine and seven right adrenalectomy) in 16 (51.8%). Two of the bilateral adrenalectom ies were applied via endoscopic surgical approach. In the histopatholo gical evaluation, diffuse hyperplasia was diagnosed in 13 (44.8%) pati ents and nodular hyperplasia in eight (26.6%), three macronodular and five micronodular hyperplasia. Adrenal cell adenoma was diagnosed in n ine (28.6%) patients. Classic dexamethasone suppression testing was pe rformed on all patients. Plasma levels of cortisol were not significan tly decreased after low-dose testing, but plasma levels of cortisol we re significantly decreased after high-dose testing in the diffuse hype rplasia group. in summary, due to the pathological changes of the adre nal cortex, dexamethasone suppression testing can differentiate betwee n the two types of Cushing's syndrome.