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APS-2 Addison Unmasked — RACP Adult Medicine MCQ

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ModerateEndocrinologyAPS-2 Addison UnmaskedRACP Adult Medicine

A 55-year-old man with type 2 diabetes, hypothyroidism, and vitiligo presents with increasing fatigue, weight loss, and postural hypotension. Na⁺ 130, K⁺ 5.8 mmol/L. Morning cortisol is 80 nmol/L. ACTH is 350 pmol/L. Anti-21-hydroxylase antibodies are positive. What additional endocrine condition has developed?

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Correct answer: D — Autoimmune polyglandular syndrome type 2

Known T2DM + hypothyroidism + vitiligo (APS-2 context) now developing Addison disease (fatigue, weight loss, postural hypotension, hyponatraemia, hyperkalaemia, very low cortisol, very high ACTH, positive 21-hydroxylase antibodies) completes APS-2. This emphasises the importance of screening for adrenal insufficiency in patients with multiple autoimmune endocrinopathies. Treatment: hydrocortisone + fludrocortisone replacement, with sick-day rules education.

Reference: Endocrine Society – 2024 – AI; eTG Endocrine 2024