Abnormalities of endocrine function in patients with clinically 'silent' adrenal masses

Because, in recent years, patients with incidentally discovered adrenal masses have been encountered increasingly, their endocrine function was investigated in basal conditions and after dynamic tests. Thirty-two patients (23 women and 9 men, aged 28-74 years) were studied. Lesion diameter, as documented by computed tomography and/or nuclear magnetic resonance imaging, ranged between 5 and 65 mm; the tumors were localized on the right in 22 patients, on the left in 5 and bilaterally in 5 cases. In basal conditions, urinary free cortisol (UEC) excretion, plasma adrenocorticotropin (ACTH) and cortisol levels were normal, except for 4 patients who showed high UFC and ACTH levels in the low-normal range. Ovine corticotropin-releasing hormone (CRH, 1 μg/k iv) was given to 18 patients, inducing normal ACTH and cortisol responses in 12, blunted responses in 4 and no response in 2 cases. No reduction in ACTH and cortisol levels after suppression tests was observed in 4 of 29 patients after dexamethasone (1 mg overnight) or in 6 of 29 after loperamide. The 4 patients who were unresponsive to both tests did not show any further inhibition after high-dose dexamethasone administration, had low plasma ACTH levels and showed impaired or absent responses to the CRH test: they were diagnosed as affected with preclinical Cushing's syndrome. An exogenous ACTH test performed in 30 patients caused a normal cortisol rise. Basal mean 17-hydroxyprogesterone (17-OHP) levels were not different from those in normal subjects. After ACTH the 17-OHP rate increase was higher than in normal subjects (17-OHP(30-0)/30 min) = 0.31 ± 0.04 vs 0.07 ± 0.01 nmol · l^-1 · min^-1; mean ± SEM, p <0.01); in particular, this parameter was elevated in 18 of 30 patients (17-OHP(30-0)/30 min) range = 0.23-1.07 vs 0.01-0.19 nmol · l^-1 · min^-1 in normal subjects). In a subset of 11 patients, serum markers of bone (bone-GLA protein (BGP) and carboxyterminal cross-linked telopeptide of type I collagen (ICTP)) and collagen turnover (aminoterminal propeptide of type III procollagen (PIIINP)) were significantly (p <0.01) lower than in normal subjects: in particular, in 2 preclinical Cushing's patients they were markedly reduced and rose after unilateral adrenalectomy. Of these 2 patients who underwent surgery, 1 showed a secondary hypoadrenalism. The histological study in 7 operated patients revealed the presence of benign adenoma in 4 cases and carcinoma, myelolipoma and hematoma in the others. In conclusion, in patients with incidentalomas endocrine testing is recommended because about two-thirds of them show subtle signs of adrenal overactivity. In patients with enzymatic defects of steroidogenesis a surgical approach is not suggested. On the contrary, the existence of a preclinical Cushing's syndrome has to be investigated carefully and followed up in order to disclose the possible appearance of clinical and/or metabolic features induced by the hypercortisolism and to suggest a surgical treatment.