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Primary adrenal insufficiency — USMLE Step 3 MCQ

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ModerateInternal Medicine (chronic management)Primary adrenal insufficiencyUSMLE Step 3

A 46-year-old woman has fatigue, weight loss, salt craving, dizziness when standing, and diffuse hyperpigmentation. Sodium is 128 mEq/L, potassium is 5.6 mEq/L, morning cortisol is low, and ACTH is elevated. Which of the following is the most likely diagnosis?

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Correct answer: A — Primary adrenal insufficiency

Hyperpigmentation, hypotension, hyponatremia, hyperkalemia, low cortisol, and high ACTH indicate primary adrenal insufficiency.

Reference: Endocrine Society adrenal insufficiency guideline