Pituitary stalk effect hyperprolactinaemia — SCE Endocrinology MCQ

Correct answer: A — Pituitary stalk disconnection causing moderate hyperprolactinaemia

Pituitary stalk disconnection causing moderate hyperprolactinaemia is best because a large sellar mass with moderate prolactin elevation suggests loss of dopaminergic inhibition from stalk compression. The alternatives are less appropriate because macroprolactinomas often produce much higher prolactin; hook effect needs dilution but is not proven; hypothyroidism would raise TSH; stress does not explain the mass. The SCE teaching point is to integrate the clinical pattern, biochemistry and context rather than treating an isolated result.

Reference: Endocrine Society hyperprolactinaemia guideline