The Curbsiders Internal Medicine Podcast #519 Mild Autonomous Cortisol Secretion
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Mar 30, 2026 Irina Bancos, adrenal endocrinologist and Mayo Clinic professor, explains mild autonomous cortisol secretion in clear clinical terms. She defines adrenal incidentalomas and why everyone needs a dexamethasone suppression test. Imaging, lab interpretation, treatment choices like adrenalectomy versus conservative care, and postoperative adrenal recovery are all covered in concise, practical discussion.
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MACS Is Biochemical Cortisol Autonomy Without Obvious Cushing
- Mild autonomous cortisol secretion (MACS) is autonomous cortisol production without classical Cushing signs.
- It often shows abnormal dexamethasone suppression with low/low-normal ACTH and may still lack overt physical features.
MACS Is Common And Clinically Relevant
- MACS is common: prevalence in incidentalomas ranges roughly 19–44%.
- MACS associates with increased cardiometabolic risk, impaired sleep, and reduced quality of life, so it's clinically important to identify.
MACS Alters Cortisol Timing Not Just Amount
- MACS often redistributes cortisol circadian rhythm rather than increasing total cortisol AUC.
- Patients have blunted morning cortisol and relatively higher evening/night cortisol, explaining normal 24‑hour urine and often-normal late-night salivary cortisol.