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Acromegaly — ABIM Board MCQ

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HardEndocrinology/MetabolismAcromegalyABIM Board

A 51-year-old man has progressive acral enlargement, prognathism, sweating, obstructive sleep apnea, hypertension, and glucose intolerance. Age-adjusted IGF-1 is elevated on repeat testing, and there is no physiologic state or medication explaining the result. Which test should next establish biochemical growth-hormone excess before localization?

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Correct answer: E — Measure GH after oral glucose and assess suppression below threshold

The best answer is “Measure GH after oral glucose and assess suppression below threshold”. After a repeatedly elevated age-adjusted IGF-1, failure of GH suppression during oral glucose testing establishes biochemical acromegaly. Random GH is unreliable because secretion is pulsatile. Pituitary MRI follows biochemical confirmation; incidental pituitary lesions are common and cannot establish hormone excess. Prolactin assesses possible cosecretion but is not a substitute diagnostic test.

Reference: Endocrine Society Clinical Practice Guideline: Acromegaly: https://www.endocrine.org/clinical-practice-guidelines/acromegaly