Endocrine Abstracts

Introduction: Adrenal incidentalomas (AIs) are frequently detected due to the increasing use of abdominal imaging for diagnostic purposes. However, few prospective studies exist with respect to their natural history, regarding their size and clinical course. The aim of this study was to report the prevalence and natural history of AIs.

Methods/design: Interim analysis of a prospective cohort study. The following tests were performed: serum cortisol nocturnal rhythm, 24 h-urinary free cortisol, low-dose dexamethasone suppression test, aldosterone to plasma-renin-activity ratio and 24 h-urinary total metanephrines and catecholamines. In cases of positive results, confirmatory tests were performed. Radiological assessment was repeated at 6–12 months and yearly thereafter.

Results: Sixty-four patients (19 (30%) males, mean age 59.7±12.1 years) were included. Follow-up data were available for 57 AIs (median time: 36 months, range 4–84). Median size was 2.5 mm (range 0.5–6.5) (unilateral adenoma in 50 (78%)). The final diagnosis was: 56 non-functioning adenomas (87.5%), 5 (7.8%) subclinical Cushing’s syndrome (SCS), 1 (1.6%) phaeochromocytoma, 1 (1.6%) aldosteronoma, and two adrenocortical carcinomas (3.2%), of which one had also SCS. Mass enlargement (9 mm) was observed in one patient (2.8%), while a decrease (7–27 mm) in 3 (8.5%). No hormonal evolution was noticed. Regarding glucose metabolism, 12, 16.7, and 20% of the patients presented deterioration in glucose metabolism at the first, second, and third year of follow-up respectively. The respective percentages for dyslipidaemia were 26, 43, and 44% and for hypertension or blood pressure worsening were 38, 44, and 48%. After excluding those with SCS, these percentages did not alter significantly. New cardiovascular events or fractures were recorded in 7.8% of the patients.

Conclusions: The vast majority of AIs involved benign, non-secretory masses. Mass enlargement was rare. More than one-third of patients developed hypertension or their lipid profile worsened, while one fifth showed deterioration in glucose metabolism, irrespectively of the presence of SCS.