Familial hyperparathyroidism is a condition whereby the overactive parathyroid disorder is inherited from another family member. Familial hyperparathyroidism is suspected when multiple family members develop hyperparathyroidism in the absence of other components of multiple endocrine neoplasia (MEN). In many but not all cases, parathyroid hyperplasia is encountered at the time of surgery. As with all parathyroid procedures at the Mount Sinai Endocrine Surgery Parathyroid Program, the extent of surgery is determined by preoperative localizing studies, surgical findings and intraoperative PTH levels. Our experts will outline a detailed, personalized treatment plan for patients with familial hyperparathyroidism.