The association of autoimmune thyroiditis and non-functional adrenal incidentalomas with insulin resistance

A Brief Look at Hashimoto's Disease, Adrenal Incidentalomas, Obesity and Insulin Resistance-Could Endocrine Disruptors Be the Other Side of the Same Coin?

Hashimoto's disease (HD) is the most common cause of hypothyroidism in developed countries. The exact pathomechanism behind it has not been clearly established; however, an interplay of genetic susceptibility, environmental triggers (including diet) and epigenetic factors seems to be involved. Among the latter, increasingly more attention has been paid to some hormonally active substances, known as endocrine disruptors, which are commonly used worldwide. HD has become a condition widely reported in the media, acting as a culprit for inexplicable weight gain, chronic fatigue or weakness. Nevertheless, the recognition of HD is undeniably increasing and represents a major public health burden. At the same time, improving access to imaging tests has increased the number of incidentally diagnosed adrenal tumors. Above all, the widespread use of chest computed tomography (CT) due to the COVID-19 pandemic has contributed to frequent incidental detection of adrenal lesions. Fortunately, a vast majority of these findings are asymptomatic benign tumors with no excessive hormonal activity, and therefore, they are defined as adrenal incidentalomas (AIs). Interestingly, recent studies have indicated that patients with AIs are more prone to obesity and insulin resistance. Although mutual relationships between the thyroid and the adrenal glands have been studied widely, still, little is known about the possible pathophysiological associations between thyroid autoimmunity and the occurrence of adrenal incidentalomas. This article presents a brief review of the common endocrine disorders with a special focus on the frequently coexisting insulin resistance and/or obesity. Furthermore, in response to the recent growing interest in endocrine disruptors, with their transgenerational epigenetic effects that influence hormonal system function, a concise overview of the topic has also been included.

Autonomous cortisol secretion in adrenal incidentalomas

Adrenal incidentalomas (AI) are one of the most frequent reasons for consultation in Endocrinology, as they are present in 3-10% of the general population. Up to 20% of them may have autonomous cortisol secretion (ACS), a term that refers to AI carriers with biochemical evidence of excess cortisol, but without the "specific" clinical signs of Cushing's syndrome. As ACS is associated with an increased risk of diabetes, obesity, high blood pressure (HBP), osteoporosis, cardiovascular events, and global mortality; its correct identification is of great importance. There are different laboratory assays to detect ACS, but all of them have some limitations. The dexamethasone suppression test is the most accepted for screening. However, there is no consensus on the cutoff point that should be used. Low levels of ACTH and DHEA-S and high urinary free cortisol are also associated with ACS, but in isolation they are of little value to establish the diagnosis. Considering its clinical implications and the lack of consensus in the diagnosis and in which is the most appropriate management of these patients, this review offers a quick reference guide of ACS, presenting an exhaustive review of the topic: its definition, epidemiology, diagnosis, clinical implications, treatment, and follow-up.