Factors Influencing Time to Decrease in Intraoperative Parathyroid Hormone (ioPTH) Levels in Patients Undergoing...

The aim of this study was to evaluate potential factors affecting the time period in which a 50 per cent parathyroid hormone (PTH) drop is observed. Eight-seven patients undergoing focused parathyroidectomy between 2011 and 2015, whose PTH values dropped to within normal range, were grouped according to whether they required > or ≤15 minutes after gland excision to achieve a 50 per cent PTH. Groups were compared according to preoperative PTH, calcium, age, glomerular filtration rate, and adenoma weight. Lower preoperative and preincision PTH levels were associated with requiring >15 minutes to achieve a >50 per cent drop in ioPTH. Time to >50 per cent ioPTH drop did not affect cure rates at one year, though a >15 minutes requirement was associated with higher serum calcium levels (P = 0.015). Lower baseline PTH and preincision PTH levels are significantly associated with a >15 minutes postexcision time to achieve a >50 per cent drop in ioPTH. Future analyses are warranted to determine whether a longer postexcision time threshold before proceeding with four-gland exploration is warranted in patients with primary hyperparathyroidism and mildly elevated preoperative PTH.