Abstract Introduction Intraoperative parathyroid hormone (ioPTH) testing is a widely accepted standard for assessing the parathyroid gland function. A decline of preoperative parathyroid hormone (PTH) levels by more than 50% is one accepted measure of parathyroid surgery adequacy. However, there may be a variation between preoperative PTH levels obtained at a clinic visit and pre-excisional ioPTH. Objective Our study explores the differences between preoperative PTH and pre-excisional ioPTH levels, and the potential impact this difference has on determining the adequacy of parathyroid surgery. Methods A retrospective study that consisted of 33 patients that had undergone parathyroid resection between September 2009 and March 2016 at a tertiary academic center was performed. Each subject's preoperative PTH levels were obtained from clinic visits and pre-excisional ioPTH levels were recorded along with the time interval between the measurements. Results There was a significant difference between the mean preoperative PTH and the pre-excisional ioPTH levels of 147 pg/mL (95% confidence interval [CI] 11.43 to 284.47; p= 0.0396). The exclusion of four outliers revealed a further significant difference with a mean of 35.09 pg/mL (95% CI 20.27 to 49.92; p< 0.0001). The average time interval between blood draws was 48 days + 32 days. A weak correlation between the change in PTH values and the time interval between preoperative and pre-excision blood draws was noted (r2 = 0.15). Conclusion Our study reveals a significant difference between the preoperative PTH levels obtained at clinic visits and the pre-excisional intraoperative PTH levels. We recommend routine pre-excisional intraoperative PTH levels, despite evidence of elevated preoperative PTH levels, in order to more accurately assess the adequacy of surgical resection.

<sec><title>Introduction</title><p>Angiosarcoma of the head and neck is a rare vascular sarcoma associated with high rates of local recurrence and distant metastasis and a poor prognosis.</p></sec><sec><title>Objective</title><p> We describe our experience treating patients with angiosarcoma of the head and neck to evaluate the outcomes, patterns of failure, and current treatments.</p></sec><sec><title>Methods</title><p> We identified six patients with angiosarcoma of the head and neck and treated at our institution between 2000 and 2013. We compared our results to the literature from 1979 to 2013.</p></sec><sec><title>Results</title><p> Mean follow-up was 42 months. Local recurrence rate was 50% with diseasespecific survival and 2-year disease-free survival rates of 33.3 and 20%, respectively. Prognostic factors included tumor size > 5 cm and surgical margin status, with no correlation between histologic grade and survival. Combined-modality therapy was only used for aggressive tumors with positive surgical margins but is suggested to improve local control and overall survival.</p></sec><sec><title>Conclusions</title><p> Our data series supports that angiosarcoma of the head and neck has a high rate of recurrence and is associated with a poor prognosis, despite current combined-modality therapy. The study highlights the importance of attaining negative margins during surgical resection, the utility of adjuvant therapies, as well as the need for continued research in developing new management strategies.</p></sec>