Diagnostic Approach to Autonomous Cortisol Secretion

Rationale for Test Repetition

The 1mg dexamethasone suppression test is the preferred screening test for identifying autonomous cortisol secretion in adrenal incidentalomas, as recommended by the Endocrine Society 1, 2
Two invalid dexamethasone suppression tests due to subtherapeutic drug levels make this the critical missing piece of diagnostic information, highlighting the need for repeat testing with confirmed adequate dexamethasone levels 1, 2

Administer 1mg dexamethasone orally at 11 PM and measure both serum cortisol AND dexamethasone levels at 8 AM to obtain a valid dexamethasone suppression test, as suggested by the Endocrine Society 1, 2

Metabolic comorbidities potentially attributable to cortisol excess, such as osteopenia, hypercholesterolemia, and overweight, are relevant in the diagnostic workup of autonomous cortisol secretion 1, 2

Establishing the presence or absence of autonomous cortisol secretion is critical because younger patients with mild autonomous cortisol secretion who have progressive metabolic comorbidities attributable to cortisol excess can be considered for adrenalectomy after shared decision-making, as recommended by the American College of Surgeons 1, 2
The American College of Endocrinology recommends that patients with autonomous cortisol secretion, even when subtle, should be considered for treatment due to the associated increased cardiovascular morbidity, mortality, hypertension, diabetes, obesity, dyslipidemia, and osteoporosis 1, 2