Adrenal incidentalomas: 1 mg dexamethasone test result in the context of cardiometabolic risk

Mild autonomous cortisol secretion (MACS) is the most common hormonal abnormality in adrenal incidentalomas. The 1 mg dexamethasone suppression test (DST) with a cutoff of 1.8 µg/dL is used to exclude hypercortisolism, yet some "non-functioning" tumors may secrete cortisol at concentrations below this threshold, potentially contributing to an adverse cardiometabolic profile. The aim of this study was to evaluate this relationship.

In this retrospective cross-sectional study, data from 1,077 patients with adrenal incidentalomas treated at a tertiary endocrinology center between 2017 and 2020 were analyzed. After applying the inclusion criteria, 807 patients were included. All patients underwent a 1 mg DST. Receiver operating characteristic (ROC) curves and area under the curve (AUC) analyses were used to assess associations between post-DST cortisol concentrations and cardiometabolic conditions, and to identify a threshold for a composite endpoint comprising the presence of coronary heart disease, chronic heart failure, or diabetes mellitus.

Patients with hypertension, coronary heart disease, heart failure, diabetes mellitus, chronic obstructive pulmonary disease, and chronic kidney disease had significantly higher post-DST cortisol concentrations. However, in multivariable logistic regression, post-DST cortisol was not independently associated with the composite endpoint after adjustment for confounders, with age and obesity remaining significant predictors. Exploratory analysis suggested that cortisol concentrations > 1.37 µg/dL were associated with a higher prevalence of the composite endpoint.

Post-DST cortisol concentrations below the standard cutoff may be associated with cardiometabolic comorbidities in patients with adrenal incidentalomas. These findings should be interpreted with caution and require confirmation in prospective studies.