Cardiovascular Risk Markers in Adults With Adrenal Incidentaloma and Mild Autonomous Cortisol Secretion

CONTEXT: Many adrenal adenomas exhibit mild autonomous cortisol secretion (MACS). Although MACS is associated with increased cardiovascular mortality, the underlying mechanisms are not fully defined. OBJECTIVE: To investigate mechanisms that may link MACS and cardiovascular mortality in adults with adrenal adenoma. DESIGN: Cross-sectional study. PATIENTS: Twenty adults with adrenal adenoma and MACS and 20 controls with nonfunctioning adrenal adenoma. 

METHODS: Reactive hyperemia index (RHI) was measured by peripheral artery tonometry and 24-hour ambulatory blood pressure monitoring (24h AMBP) was performed. Indices of insulin secretion and sensitivity were estimated by measuring glucose and insulin fasting and following a mixed meal. 

MAIN OUTCOME MEASURE: The primary outcome was the difference in RHI between participants with MACS vs nonfunctioning adrenal adenoma. 

RESULTS: The average cortisol after 1-mg dexamethasone and urinary free cortisol were higher in patients with MACS. There was no significant difference in fasting RHI (2.0 [interquartile range (IQR) 1.6-2.4] vs 2.0 [IQR 1.7-2.2, P = .72), but postprandial RHI was higher in patients with MACS (2.2 [1.8-2.7] vs 1.8 [1.5-2.2], P = .04). 24-hour ambulatory blood pressure monitoring and Matsuda index were not significantly different in the groups. Fasting glucose and glucose area under the curve after the mixed meal were higher and insulinogenic index was lower in participants with MACS. 

CONCLUSION: Adults with adrenal adenoma and MACS do not have fasting endothelial dysfunction and postprandial endothelial function may be better. These patients have fasting and postprandial hyperglycemia with lower insulin secretion, which may underlie the association between MACS and increased cardiovascular mortality.