Pathological examination showed 390 (88.8%) single adenomas, 11 (2.5%) double adenomas, 19 (4.3%) diffuse hyperplasia, six (1.3%) non-pathological tissue (but normalized postoperative PTH and calcemic response), seven (1.5%) atypical adenomas (one intrathyroidal) and six (1.3%) malignant parathyroid tumors. Here, PTH is linked to malignant tumor of parathyroid gland.