ACTH-independent hypercortisolism across the cardiometabolic spectrum

Background: Accumulating evidence suggests that the prevalence of hypercortisolism in patients with cardiometabolic risk factors is much higher than previously thought. This study aimed to evaluate the prevalence of ACTH-independent hypercortisolism across the spectrum of cardiometabolic risk. Methods: Participants were prospectively recruited into three cohorts to undergo protocolized assessment of adrenal physiology:1) normotensive participants; 2) participants with hypertension and obesity, but without diabetes; 3) participants with diabetes and overweight/obesity. All participants (n=216) underwent overnight 1 mg dexamethasone suppression testing followed by cosyntropin stimulation test, and 24-hour urine free cortisol (UFC) testing. ACTH-independent hypercortisolism was defined as post-dexamethasone serum cortisol >1.8 g/dL (50 nmol/L) with a concomitant post-dexamethasone ACTH [&le;]10 pg/mL (2.2 pmol/L). Result: 16 of 216 (7.4%) participants were found to have ACTH-independent hypercortisolism, including 5.6% (4/71) in the normotensive cohort, 6.2% (5/81) in the hypertension-obesity cohort and 10.9% (7/64) in the diabetes-obesity cohort. Age, body mass index, hemoglobin A1c, blood pressure, renal function, morning ACTH, and 24-hour UFC were similar among those with and without ACTH-independent hypercortisolism. Following cosyntropin stimulation, those with ACTH-independent hypercortisolism had higher stimulated cortisol levels (greater ACTH-dependent responses) when compared to those without ACTH-independent hypercortisolism: 25.8 +/- 4.5 versus 20.6 +/- 4.1 g/dL (711 +/- 124 v. 568 +/- 113 nmol/L) (P<0.001). Conclusions: In this prospective study, the prevalence of ACTH-independent hypercortisolism paralleled the burden of cardiometabolic risk features. ACTH-independent hypercortisolism was associated with greater ACTH-stimulable cortisol production, identifying a unique biochemical phenotype. These findings reveal new insights into cortisol pathophysiology as a function of ACTH and cardiometabolic risk profiles.