This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
[{'content': 'The most common underlying aetiology of primary hyperparathyroidism is \nSelect and explain. \nA. Parathyroid adenoma, B. MEN-1, C. MEN-2A, D. Parathyroid adenocarcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The underlying aetiology of PHPT is usually a solitary parathyroid adenoma, however, in a small number of patient (2-4%), there are double adenomas. It may occur in a sporadic fashion or it can be familial (MEN type 1 or type 2A, hyperparathyroidism-jaw tumour syndrome (HPT-JT)Ref: Bailey and Love 27e pg: 826', 'role': 'assistant'}]