Subclinical hypercortisolism in incidentally detected adrenal adenoma

Aim of study: To define in a prospective study the prevalence and manifestations of subclinical hypercortisolism in a sizeable group of patients with incidentally detected adrenal adenoma. Such tumour - although usually clinically silent - may cause discrete endocrine dysfunctions. Patients and methods: Between 1990 and 1994, 85 consecutive patients with incidentally discovered adrenal adenoma were investigated (54 women, 31 men; mean age 54.1 +/- 13 [24-81] years). In addition to history and clinical examination all patients had a low-dose dexamethasone suppression test (2 mg) and their morning basal plasma ACTH concentration was measured. The diagnosis of subclinical hypercortisolism was made if there was inadequate suppression of cortisol after dexamethasone administration, plasma ACTH level was decreased and there were no clinical signs of Cushing's syndrome. Results: Five of the patients fulfilled the criteria of subclinical hypercortisolism (prevalence of 6%). One of them had oligomenorrhoea, another arterial hypertension, and three had mild obesity (body mass index > 25). In all patients there was histological proof of adrenal adenoma, Postoperatively the patient with oligomenorrhoea had normal menstrual cycles, while in all others with subclinical hypercortisolism excision of the tumour had no influence on their clinical state. Conclusions: Subclinical hypercortisolism is rare, but is one of the most common endocrine disorders in patients with incidental adrenal adenoma. It can be diagnosed only by hormonal analysis. Once the latent cortisol excess has been eliminated, those symptoms which are due to hormonal abnormality may regress, but nonspecific signs, such as obesity or hypertension, may not necessarily improve.