A 22-year-old man undergoes evaluation after his sister was diagnosed with multiple endocrine neoplasia type 1. Genetic testing confirms an inactivating MEN1 (menin) mutation. Which endocrine tumour is the MOST COMMON initial manifestation of this syndrome?
- A Gastrinoma
- B Prolactinoma
- C Primary hyperparathyroidism ✓
- D Insulinoma
Correct answer: C. Primary hyperparathyroidism
Explanation
In MEN1, primary hyperparathyroidism due to multiglandular parathyroid hyperplasia affects about 90% of patients and typically appears first, often before age 30. Enteropancreatic tumours such as gastrinoma rank second in frequency, followed by pituitary adenomas, most commonly prolactinoma. Insulinoma is far less common. Parathyroidectomy timing follows calcium levels and symptoms rather than immediate surgery in asymptomatic mutation carriers under surveillance.
Reference: Williams Textbook of Endocrinology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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