2.6. Definitions

Our center defines the parathyroid decline rate as the difference between preoperative PTH and intraoperative PTH levels, expressed as a percentage of preoperative PTH. Intraoperative PTH levels were measured by collecting venous blood 30 min after the intraoperative removal of the diseased parathyroid glands. The parathyroid hormone levels were measured in pg/mL. Laboratory tests included the levels of serum calcium (Ca; reference range, 2.00–2.60 mmol/L), serum phosphate (P; reference range, 0.81–1.45 mmol/L), alkaline phosphatase (ALP; reference range, 30.00–120.00 IU/L), and serum calcitonin (Cal; reference range, 0.50–6.00 pg/ml).