Gina Trinh1, Salem I Noureldine2, Jonathon O Russell3, Nishant Agrawal4, Michael Lopez2, Jason D Prescott5, Martha A Zeiger5, Ralph P Tufano6. 1. Queen's University School of Medicine, Kingston, Ontario, Canada. 2. Department of Surgery, The George Washington University School of Medicine and Health Sciences, Washington, DC. 3. Division of Head and Neck Endocrine Surgery, Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD. 4. Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Chicago, Chicago, IL. 5. Endocrine Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD. 6. Department of Surgery, The George Washington University School of Medicine and Health Sciences, Washington, DC. Electronic address: rtufano1@jhmi.edu.
Abstract
BACKGROUND: During parathyroidectomy with intraoperative parathyroid hormone monitoring, the successful removal of a hypersecreting gland(s) resulting in normocalcemia is indicated by a >50% decrease in intraoperative parathyroid hormone level, typically into the normal range. Some patients, however, will have baseline parathyroid hormone levels within the normal range. We sought to determine the utility of intraoperative parathyroid hormone testing in these patients. METHODS: We retrospectively studied all patients who underwent parathyroidectomy for primary hyperparathyroidism at our institution over a 10-year period. RESULTS: Overall, 317 (17%) patients had parathyroid hormone within the normal range at the onset of operation (baseline intraoperative parathyroid hormone), and 1,544 (83%) had classic primary hyperparathyroidism. The intraoperative parathyroid hormone degradation was slower in normal baseline intraoperative parathyroid hormone patients than classic primary hyperparathyroidism patients, though this did not reach statistical significance (P < .254). A >50% intraoperative parathyroid hormone decrease predicted cure in 98.7% of normal baseline patients and 98.8% of classic primary hyperparathyroidism patients (P = .810). Normal baseline patients had a lesser cure rate the longer it took to achieve a 50% decrease intraoperatively; however, the cure rate was constant at any time point the 50% decrease occurred in patients with classic primary hyperparathyroidism (P < .05). CONCLUSION: The 50% rule delineating operative cure can be applied with equal confidence to patients with normal range, baseline intraoperative parathyroid hormone. Moreover, the time at which the 50% drop is achieved impacts operative success rates in these patients.
BACKGROUND: During parathyroidectomy with intraoperative parathyroid hormone monitoring, the successful removal of a hypersecreting gland(s) resulting in normocalcemia is indicated by a >50% decrease in intraoperative parathyroid hormone level, typically into the normal range. Some patients, however, will have baseline parathyroid hormone levels within the normal range. We sought to determine the utility of intraoperative parathyroid hormone testing in these patients. METHODS: We retrospectively studied all patients who underwent parathyroidectomy for primary hyperparathyroidism at our institution over a 10-year period. RESULTS: Overall, 317 (17%) patients had parathyroid hormone within the normal range at the onset of operation (baseline intraoperative parathyroid hormone), and 1,544 (83%) had classic primary hyperparathyroidism. The intraoperative parathyroid hormone degradation was slower in normal baseline intraoperative parathyroid hormonepatients than classic primary hyperparathyroidismpatients, though this did not reach statistical significance (P < .254). A >50% intraoperative parathyroid hormone decrease predicted cure in 98.7% of normal baseline patients and 98.8% of classic primary hyperparathyroidismpatients (P = .810). Normal baseline patients had a lesser cure rate the longer it took to achieve a 50% decrease intraoperatively; however, the cure rate was constant at any time point the 50% decrease occurred in patients with classic primary hyperparathyroidism (P < .05). CONCLUSION: The 50% rule delineating operative cure can be applied with equal confidence to patients with normal range, baseline intraoperative parathyroid hormone. Moreover, the time at which the 50% drop is achieved impacts operative success rates in these patients.