Puvaneswaralingam S, Kjellbom A, Lindgren O, et al. - Given the significance of accurately diagnosing autonomous cortisol secretion (ACS) during the investigation of adrenal incidentalomas, but a low specificity of cortisol ≥ 50 nmol/L after overnight dexamethasone suppression (cortisol_ONDST), researchers sought to examine if ACTH following overnight dexamethasone suppression (ACTH_ONDST) and cortisol following a 2‐day dexamethasone suppression test (cortisol_2‐DAYDST) can aid in determining HPA axis suppression during ONDST. They conducted a cross‐sectional study including patients with adrenal incidentalomas and basal ACTH ≥ 2.0 pmol/L who underwent ONDST. Findings suggest the utility of ACTH_ONDST and ACTH_ONDST/ACTH ratio (ACTH ratio) as markers of HPA axis suppression in the evaluation of adrenal incidentalomas. They suggest that ACS should be suspected in cases with cortisol_ONDST ≥ 50 nmol/L with ACTH_ONDST < 0.6 pmol/L or ACTH ratio < 18%.