Endocrine Abstracts

Background: Intraoperative PTH (IOPTH) measurement during surgery for primary hyperparathyroidism (PHPT) predicts post-operative cure and provides important information during surgery. In 2017, we set-up IOPTH measurement on a laboratory-based mainline immunoassay analyser. Samples collected are – pre-incision(S1), pre-excision(S2) and 20mins post-excision(S3). A drop of >50% in S3 from either S1 or S2 is considered to be indicative of cure.Patients and MethodsWe reviewed the records of patients with PHPT who had parathyroidectomy between 2017-2024 and recorded demographic, biochemical, surgical and histological details to assess the predictive accuracy of IOPTH measurement and its impact on the surgical procedure.ResultsWe had full biochemical and IOPTH details on 157 patients. Mean age 61 years, 78% females, mean serum calcium 2.93mmol/L. 142 patients had >50% drop in PTH and of these 140(99%) patients were cured. One of the two patients who was not cured was subsequently confirmed to have MEN-1. 15 patients had <50% drop and in all 15 patients, surgery was extended with further IOPTH measurement. In 10/15 patients IOPTH values dropped by >50% and all were cured, while in 5 patients PTH fall remained <50% and none was cured. The time taken to receive IOPTH result was comparable to the time taken for frozen section result.Summary>50% fall in IOPTH accurately predicted cure in 98.5% patients allowing the surgeon to undertake limited surgery with lower risk of local complications. <50% fall predicted absence of cure in 100% of patients allowing the surgeon to extend surgery. Following the extension once again IOPTH predicted cure or its absence with 100% accuracy.ConclusionsIOPTH as measured in our centre accurately predicted the surgical outcome, thereby (a) reducing surgical time and local complications and (b) guiding the surgeon to extend surgery with reduction in frequency of surgical failure.