MEN1 and adenoma: Given the genetic predisposition in MEN1 mutated individuals of every parathyroid cell to lose the second wild type copy of the MEN1 gene and to randomly develop multiple hyperplasia/adenoma (affecting, asynchronously, and asymmetrically, all four glands during the patient's lifetime), and because of the common (up to 30%) presence of supernumerary and/or ectopic parathyroids (16), all our patients were followed-up by a yearly surveillance program for serum PTH and calcium to monitor post-surgical persistence and recurrences.