A 68-year-old woman wasreferred for evaluation of an incidentally discovered left adrenal mass.Her chief complaint was body weight loss. She showed no symptoms or signs suggestive of Cushing's syndrome. The circadian rhythm of blood pressure was also normal. Hormonal assessment revealed an abnormal diurnal variation in serum cortisol levels, suppressed baseline plasma adrenocorticotrophic hormone, and nonsuppression of serum and urinary cortisol with the dexamethasone suppression test. Adrenal

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... cintigraphy with 131I-6-beta-iodomethyl-norcholesterol showed uptake on the left adrenal and inhibition of the contralateral adrenal gland. She was diagnosed as pre-clinical Cushing's syndrome. Due to the lack of clinical symptoms and the risks of surgery, we emphasize the importance of careful assessment of the cortisol metabolism and scintigraphic scanning under dexamethasone suppression to avoid post-surgical Addisonian crisis. (Internal Medicine 37: 528-533, 1998)