N. C. Luehmann1, J. A. Cirino1, P. F. Czako1, S. Nagar1 1William Beaumont Hospital,Department Of Surgery,Royal Oak, MI, USA
Introduction: The advent of intraoperative parathyroid hormone (ioPTH) monitoring has enhanced the efficacy of parathyroidectomy by allowing surgeons to ensure that all abnormal parathyroid tissue is excised in the operating room. Although ioPTH monitoring has been a revolutionary development, limitations are faced when initial ioPTH values do not meet accepted criteria. Surgeons must decide whether to proceed with further dissection or wait for additional ioPTH levels to return. The purpose of our study was to review our 5-minute post-gland excision ioPTH (5-min ioPTH) data to determine if there are trends that identify patients at risk for multigland disease, thereby allowing further dissection to begin sooner.
Methods: A retrospective chart review was performed for all patients who underwent parathyroidectomy with ioPTH monitoring from January 2001 through March 2015 at Beaumont Hospital’s Royal Oak campus. We specifically studied patients who had a 5-min ioPTH level drawn. Patients were excluded if they were less than 18 years old, had surgery for secondary or tertiary hyperparathyroidism, re-operative parathyroidectomy, concomitant thyroid procedures, other prior neck operations, or a thoracic procedure to remove an intrathoracic parathyroid gland. Methodology used in previous studies looking at this idea was employed in our study. Patient’s charts were reviewed to document baseline pre-excision PTH level, 5-min ioPTH level, final pathology with respect to single adenoma (SA), double adenomas (DA), or four gland hyperplasia (4G), and post-operative calcium levels to determine cure, persistence, or recurrence.
Results: In total, 621 patients had a 5-min ioPTH level and were included. The median baseline ioPTH for the cured, persistence, and recurrence groups was similar at 134, 119, and 136 pg/mL, respectively (p=0.18). However, the median 5-min ioPTH was lower in the cured group compared to the persistence and recurrence groups (37, 58 and 58 pg/mL, respectively) (p=0.002). Similarly, the percent decline in PTH from baseline to 5-min ioPTH was significantly greater in the cured group at 74% versus 47% in the persistence and 51% in the recurrence groups (p<0.001). Within the subset of patients cured from the index operation, median 5-min ioPTH between those with SA, DA, and 4G was 36, 51, and 93 pg/mL, respectively (p<0.001). Percent decline in PTH from baseline to 5-min ioPTH was 74% for the SA group and decreased to 60% in the DA group and 17% in the 4G group (p<0.001). Finally, a ROC analysis conducted using the same subset of patients indicated that a 35% decline from baseline to the 5-min ioPTH is needed to best distinguish a SA from DA or 4G (sensitivity 49.4% and specificity 98.9%).
Conclusion: Our results indicate that 5min-ioPTH values are lower in SA versus DA and 4G. Additionally, we found that if a decline of >35% between baseline and ioPTH is not achieved, consideration for further dissection is warranted.