The specific aims of this study are to determine the safety and efficacy of minimally invasive radioguided parathyroidectomy, to determine the positive and negative predictive value of sestamibi scanning to detect parathyroid adenomas, and to differentiate adenomas from parathyroid hyperplasia. In addition, this study aims to determine the value of intraoperative parathyroid hormone assay to verify biochemical cure of primary hyperparathyroidism, to determine whether minimally invasive radioguided parathyroidectomy is cos-effective, and to collect abnormal parathyroid tissue at the time of surgery for tissue analysis.