<prompt> A common cause of Primary hyperparathyroidism is:Multiple parathyroid adenomasSolitary parathyroid adenomaAdrenal hyperplasiaEctopic PTH production  <response>: Answer is B Solitary parathyroid adenoma : The most common cause of primary hyperparathyroidism is a parathyroid adenoma. A singlesolitary abnormal gland is the cause in approximately 80 of patients - Harrison The abnormality of the gland is usually a benign neoplasm or adenoma and rarely a parathyroid carcinoma 