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Stalk effect hyperprolactinaemia — SCE Endocrinology MCQ

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HardPituitaryStalk effect hyperprolactinaemiaSCE Endocrinology

A 41-year-old man has headache and low libido. Prolactin is 1,200 mIU/L and MRI shows a 3 cm non-functioning macroadenoma compressing the stalk. Visual fields show superior temporal defects. What is the most likely cause of hyperprolactinaemia?

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Correct answer: C — Pituitary stalk disconnection

Moderate prolactin elevation with a large non-functioning macroadenoma suggests stalk effect due to reduced dopaminergic inhibition. Macroprolactinomas often produce much higher prolactin levels, though assay hook effect should be considered when discordant. Visual field loss needs specialist surgical review.

Reference: Endocrine Society Hyperprolactinaemia Guideline