Epidemiology of Cushing's syndrome and subclinical disease.

Adenomatous lesions of the adrenal are commonplace. Advances in imaging technology have resulted in the discovery of increasing numbers of these lesions. A variety of hormonal and anatomic evaluations have been suggested to distinguish between the benign and potentially harmful of these lesions. Among the suggested evaluations is assessment of the feedback regulation of cortisol secretion. Several studies have confirmed that approximately 10% of the adenomas secrete cortisol in at least a partially unregulated manner. These patients, defined as having either subclinical or preclinical Cushing's syndrome, frequently undergo extensive diagnostic testing and on occasion, adrenalectomy. The relative infrequency of Cushing's syndrome in the general population suggests strongly that the vast majority of individuals identified by subjecting all patients with incidentally discovered adrenal masses to screening tests for excess cortisol secretion will never progress to clinically significant disease (clinical Cushing's syndrome). Thus, testing of this nature in the absence of clinical findings consistent with Cushing's syndrome is counterproductive and should generally not be performed. Individuals with these masses should, however, receive close clinical follow-up and testing initiated if any findings suggestive of Cushing's syndrome develop. The application of screening tests in a relatively unselected population is clinically ineffective and can be deleterious when patients without disease undergo subsequent invasive procedures. The clinical epidemiology af adrenal Cushing's syndrome, the natural history of incidentally discovered adrenal lesions, and the lack of clearly documented benefits in removing lesions from patients with subclinical disease argue strongly against use of a biochemical screen ion the decision to operate.(ABSTRACT TRUNCATED AT 250 WORDS)