B. D. Graffree1, R. Martin1, A. Quillo1 1University Of Louisville School Of Medicine,Surgical Oncology/Surgery/Medicine,Louisville, KY, USA
Introduction: Parathyroid hormone (PTH) monitoring during minimally invasive parathyroidectomy (MIP) has become a staple in optimizing cure by confirmation of the removal of the hyperfunctioning parathyroid tissue. However, insufficient PTH drop within 10 minutes is noted in a number of patients. The aim of this study was to evaluate potential factors affecting the time period in which a fifty percent PTH drop is observed.
Methods: Patients included in this study were those who underwent MIP by a single surgeon between between December 2011 and April 2015 with a single parathyroid gland removed and by definition whose PTH values eventually dropped by 50% and to within normal range. This data was collected under IRB protocol after patient consent in a prospective clinical outcomes database. Patients were then grouped as follows: 1) 50% PTH drop at 10 min after gland excision 2) 50% drop at 15 min 3) 50% drop greater than 15 min. These groups were compared according to pre-operative PTH and calcium, age, glomerular filtration rate (GFR), and weight of adenoma. Statistical analysis was performed by Oneway Anova.
Results: A total of 88 patients fit the selection criteria. There were 62 (70%) patients that experienced a PTH drop at ten minutes; 18 (20%) patients with PTH drop at 15 minutes; and 9 (10%) patients with PTH drop greater than 15 minutes. Of the factors analyzed, statistical significance was only shown in the postoperative PTH values (p=0.001). However, patients with a 50% PTH drop at ten minutes displayed a higher mean GFR than the other groups. This difference approached statistical significance (p=0.0783).
Conclusion: Factors such as age, pre-operative PTH and calcium have no significant effect on the time required for a patients PTH to drop by 50%, indicating a successful operation. Because GFR was near statistical significance, it is plausible to consider GFR levels in deciding how long a surgeon should wait intra-operatively to draw PTH levels. Although postoperative PTH was shown to be statistically significant between the groups, there is very little use for this in recommendations for clinical protocol. Future study should involve a larger patient size in order to provide a more accurate assessment of factors that could cause this difference, if any.