Adrenal Incidentaloma Workup — RACP Adult Medicine MCQ

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ModerateEndocrinologyAdrenal Incidentaloma WorkupRACP Adult Medicine

A 50-year-old woman has an incidental 2.5 cm left adrenal mass found on CT for abdominal pain. The mass has homogeneous low density (<10 HU on unenhanced CT). She is normotensive. What is the minimum biochemical workup required?

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Correct answer: D — Plasma metanephrines + 1 mg overnight DST + aldosterone:renin ratio (if hypertensive)

All adrenal incidentalomas ≥1 cm require biochemical workup to exclude hormone hypersecretion, regardless of imaging characteristics. The minimum workup per Endocrine Society 2016 guidelines: (1) plasma free metanephrines (exclude phaeochromocytoma — mandatory for all), (2) 1 mg overnight DST (exclude autonomous cortisol secretion), and (3) aldosterone:renin ratio if hypertensive/hypokalaemic. Low density (<10 HU) favours adenoma.

Reference: Endocrine Society – 2016 – Adrenal Incidentaloma; ESA 2024