THE FUNCTIONAL SPECTRUM OF ADRENOCORTICAL ADENOMAS

Adrenocortical adenomas (ACA) are frequently discovered at autopsy. No wadays, modern radiologic techniques incidentally uncover the usually silent ACA during lifetime. On the basis of various reports and the re sults of endocrine tests, i.e. dexamethasone suppression (DST) and CRH response, we characterize 3 major types of functioning ACA. Type I AC A (cortisol <100 nmol/l after 1 mg dexamethasone (DXM)) comprises the majority of the so-called 'nonfunctioning' adrenocortical adenomas. Ho wever, these adenomas may not be 'truly nonfunctioning' ACA, as their mean F(MAX)/ACTH(MAX)-ratio after CRH is significantly higher than in controls without ACA. Also, 19-iodocholesterol adrenal scan has shown persistent adrenal uptake despite DXM administration in some patients with normal DST. Type II ACA ('pre-Cushing's') is comparable to the eu thyroid autonomous adenoma. The results of function tests suggest the existence of an ACTH-hyperresponsive subtype. Finally, type III ACA ar e associated with overt hypercortisolism. An ACTH-responsive and an AC TH-unresponsive form can be characterized. A continuous functional spe ctrum and the transition between the different types of adenomas is di scussed.