Incidentally found adrenal tumours: results of investigation of the pituitary-adrenal axis.

In the last 7 years 64 patients (48 women, 16 men, aged 25-75 yrs) with incidentally found asymptomatic adrenal tumours have been observed in the Department of Endocrinology. In 11 patients a routine clinical investigations revealed metastatic tumours at the adrenal glands. In the remaining 53 patients the diameter of the adrenal tumours was < or = 3 cm. Only two of them were treated surgically; the rest has been observed regularly and ultrasonographic examinations have been repeated every 3 to 6 months. Twenty three patients with adrenal tumours < 3 cm of diameter were treated by surgery. The macroscopical examination revealed adrenal cortical adenoma in 11 cases, adrenocortical carcinoma in seven, and pheochromocytoma in 5 patients. The investigation of the pituitary-adrenal system (urinary excretion of 17-OHCS before and during dexamethasone administration, 17-KS, "free" corticosteroids, plasma ACTH, cortisol and S-DHA levels) did not reveal any abnormality except that in 10 patients the plasma ACTH concentration was low, especially in the morning. These values were significantly lower as compared with the remaining patients and with control group. One of the possible interpretations is a pituitary suppression by only periodically increased concentrations of the corticosteroids.