Endocrine Abstracts

Background: Adrenal incidentalomas are common amongst the general population, incidence increases with age. Radiological and biochemical assessment of all lesions >1 cm is standard practice to determine appropriate future management, as per current European guidelines. We report the experiences of a recently formalised adrenal multi-disciplinary pathway in a large UK teaching hospital, where all adrenal incidentalomas are referred and systematically assessed.

Methods: 902 patients presenting with an adrenal incidentaloma discussed at a multi-disciplinary team (MDT) meeting over 2.5 years were retrospectively reviewed. Data were collected on demographics, imaging, biochemistry and where relevant diagnosis, surgical outcome and histopathology. Functional testing included overnight dexamethasone suppression tests, aldosterone, plasma renin activity and plasma metanephrines. Prism v9.3.1 was used for statistical analysis.

Results: Of the 902 patients, 47% were male. Mean age was 64 years ± 14 (SD). 865 patients had some form of functional testing, of which 45% had initial results suggestive of endocrine hypersecretion. 899 had imaging available, 82.7% had unilateral lesions with 64.1% found within the left adrenal gland. Mean lesion size 2.9 cm±2.4 (range 0.6-21 cm). Mean Hounsfield Units was 4.88±15.7. 39.8% of ONDST performed had an unsuppressed cortisol (greater than 50nmol/l). 21.2% of plasma metanephrine tests performed were elevated above the normal reference range. From the entire cohort, 5.6% were diagnosed with phaeochromocytoma, 3.7% with primary aldosteronism, 9.2% had mild autonomous cortisol secretion, 2.1% had adrenal cortical carcinoma and 0.9% had paraganglioma. Other diagnoses include metastases, lymphoma and haemorrhage. There was an overall mortality of 5.8% over the follow-up period (1-3 years).

Conclusion: Our results demonstrate a very high proportion of patients with incidental adrenal nodules have abnormal endocrine functional testing. ONDST in particular had a high positivity rate. There are significant confounders to most of these tests, with the likelihood some results will be false positives. Therefore, multidisciplinary expertise is crucial for appropriate interpretation and determination of further assessment in every case. This systematic multi-disciplinary approach to incidental adrenal nodules has led to earlier detection of a large number of phaeochromocytomas, patients with primary aldosteronism and malignancy, who may have not otherwise been referred in our centre.