Background: Adrenal masses discovered incidentally during imaging studies (adrenal incidentalomas AIs) are common and prompt investigations to exclude secretory lesions and malignancy. Uncertainty exists over the best management strategy of AI.
Objective: To monitor the current practice against the local protocol and existing guidelines; to identify the biochemical and imaging outcomes in a single centre cohort.
Methods: Retrospective review of medical records, biochemistry and imaging of all 125 patients referred to our centre between 2005 and 2009 with an AI.
Results: Eighty-two percent of the AIs were unilateral, average diameter on imaging was 20.4 mm. Eighty-seven percent of the patients had at least one repeat scan done, with a 17 months mean interval between the first and the last scan. 5.5% of AIs increased ≥5 mm in size on follow up, 7.8% decreased ≥5 mm, while 86.7% remained unchanged.
Following our local protocol and including only patients who completed all the investigations (82%), 67% patients were diagnosed with non secretory benign adenomas, 2% primary hyperaldosteronism, 2% phaeochromocytoma, 1% adrenal metastasis and 5% with other diagnosis. 24 patients (23%) failed to suppress on a low dose or overnight dexamethasone suppression test using a cut-off of 50 nmol/l; of those 4 were diagnosed with adrenal Cushings, 5 had false positive results. None of the remaining 15 patients had clinical features of Cushings syndrome and all but one had normal 24 h urinary free cortisol excretion. Finally, seven patients with at least two abnormal tests of the HPA axis were diagnosed with mild cortisol secretion. The use of a higher cut-off for post dexamethasone cortisol (83 nmol/l) would exclude four of these patients, while the recommended by the NIH consensus cut-off (138 nmol/l) would exclude all these patients but one.
Conclusion: Eleven percent of the AIs in our cohort were functional. Altering the post dexamethasone cortisol cut-off in accordance to published guidelines radically changed the performance of the suppression test in our cohort.