Intraoperative Parathyroid Hormone Assay Research Articles

A commentary on 'The role of rapid intraoperative parathyroid hormone (ioPTH) assay in determining outcome of parathyroidectomy in primary hyperparathyroidism: A systematic review and meta-analysis'.

A commentary on 'The role of rapid intraoperative parathyroid hormone (ioPTH) assay in determining outcome of parathyroidectomy in primary hyperparathyroidism: A systematic review and meta-analysis'.

Findings of pilot study following the implementation of point of care intraoperative PTH assay using whole blood during surgery for primary hyperparathyroidism.

To report findings of pilot study using a novel point of care (POC) intraoperative parathyroid hormone (IOPTH) assay for parathyroid hormone (PTH) using whole blood during surgery for primary hyperparathyroidism (PHPT). Patients undergoing surgery for primary hyperparathyroidism from March to November 2022 where intraoperative PTH assay was performed using the NBCL CONNECT IOPTH and the laboratory PTH assay were included (group 1). The biochemistry results were reviewed to determine concordance between NBCL and lab PTH values and diagnostic test parameters of the NBCL CONNECT assay. 'In-theatre' times were then compared with a historical cohort (group 2) where the lab-based IOPTH assay alone was used. Of the 141 paired samples in group I, correlation between NBCL and the lab assay was high (rho=0.82; p<0.001). PTH levels using the NBCL assay dropped satisfactorily (>50% of the basal or 0 min sample; whichever was lower - i.e. positive test) in 23 patients; giving a positive predictive value of 100%. Of the 9 patients that did not demonstrate a drop, two were true negative (negative predictive value of 22%) leading to cure after excision of another gland. Group 1 (150 mins) had a significantly shorter 'in-theatre' time compared to group 2 (167 mins) (p=0.007); despite much higher use of near infra-red autofluorescence (NIRAF) (72% vs 11.6% in group I and 2 respectively). The NBCL CONNECT POC IOPTH assay gives comparable results to lab based PTH assays and can be performed without need for a centrifuge or qualified technicians. Surgeons, however, need to be aware of the potential for false-negative results.

Robot-Assisted Parathyroidectomy Using Indocyanine Green (ICG) Fluorescence in Primary Hyperparathyroidism.

Background and Objectives: Surgical treatment for primary hyperparathyroidism (PHPT) has evolved from bilateral exploration through a long transcervical incision to focused parathyroidectomy with a minimal incision above the pathologic gland. Recently, endoscopic or robot-assisted parathyroid surgery without direct neck incision has been introduced. The aim of this study was to investigate the effectiveness of indocyanine green (ICG) fluorescence as a new method for the visual identification of abnormal hyperfunctioning parathyroid glands in robot-assisted parathyroidectomy using FireflyTM technology. We also aimed to conduct a comparative analysis between robot-assisted parathyroidectomy and conventional focused parathyroidectomy in order to identify clinical differences between the two surgical approaches. Materials and Methods: A total of 37 patients with PHPT underwent parathyroidectomy at a single university hospital between September 2018 and December 2022. Thirty-one patients underwent open focused parathyroidectomy (open group), and six patients underwent robot-assisted parathyroidectomy (robot group). Pre-operative localization via parathyroid SPECT-CT and an intraoperative parathyroid hormone (IOPTH) assay were used to successfully remove the pathologic parathyroid in both groups. ICG was administered only in the robot group. Results: Pathologic parathyroid showed a persistent fluorescence pattern under near-infrared vision. After the removal of the fluorescent parathyroid gland, IOPTH was normalized in all six patients in the robot group. However, the open group showed shorter hospital stays (1.8 ± 1.2 vs. 3.0 ± 0.0 days, p < 0.001) and shorter operation times (91.1 ± 69.1 vs. 152.5 ± 23.6 min, p = 0.001) than the robot group. After 6 months of surgery, PTH, calcium, and ionized calcium levels were all normalized without significant differences between the groups. Conclusions: Robot-assisted parathyroidectomy using ICG is helpful for the visual identification of the pathologic parathyroid gland. The advantage of robot parathyroidectomy is a better cosmetic outcome. However, it still does not show better clinical outcomes than conventional open focused parathyroidectomy.

Investigating the effectiveness of intraoperative rapid parathyroid hormone assay in parathyroidectomy surgery in patients with secondary hyperparathyroidism

IntroductionThe use of Rapid Intraoperative parathyroid hormone (Io-PTH) assay during surgery in the management of parathyroid tissue in cases of primary hyperparathyroidism has been proven to be effective, while its utilization in secondary hyperparathyroidism (SHPT) has been rarely reported. In the present study, we aim to demonstrate the application of rapid Io-PTH assay in patients with SHPT following chronic kidney disease undergoing parathyroidectomy surgery.MethodIn this prospective study, five blood samples were taken from patients undergoing parathyroidectomy and upper thymectomy. Among the samples, two were pre-excision, including prior to the first incision, after exploration, and before parathyroids resection. Two additional samples were taken 10 and 20 min after the excision of the parathyroid glands. Another sample was collected twenty-four hours after the operation. Serum Calcium levels and PTH levels were evaluated and analyzed.ResultsWe successfully managed SHPT in all 36 patients in our study. The patients included 24 males (66.7%) with a mean age of 49.97 ± 14.92. The mean PTH decreased significantly at 10 min, 20 min, one day, and six months after surgery (P < 0.001). The highest reduction occurred 10 min after removal of the parathyroid glands so the mean PTH compared to time zero was reduced from 1737 to 439, and in 100% of cases, more than 50% reduction was seen in PTH.ConclusionA 60% or more reduction in PTH Rapid at 10 min after parathyroidectomy has an accuracy of 94.4% and a positive predictive value of 100%. Thus, if the PTH level does not decrease by more than 60% at 10 min or more than 80% at 20 min, tissue exploration is continued with the aim of finding the ectopic parathyroid gland.

A 15-year experience: intraoperative parathyroid hormone assay for the management of primary hyperparathyroidism in a UK endocrine surgical unit.

This study aims to evaluate the outcomes of first-time parathyroidectomy for primary hyperparathyroidism using intraoperative PTH (IOPTH) assay in the light of the UK National Institute for Health and Care Excellence (NICE) guidelines for the management of primary hyperparathyroidism. This is a retrospective cohort analysis of a prospectively maintained database of endocrine surgery in a tertiary centre. Preoperative radiological localisation (concordance and accuracy), intraoperative PTH parameters and adjusted serum calcium at minimum 6-month follow-up were analysed. The accuracy of IOPTH to predict post-operative normocalcaemia and the number needed to treat (NNT) within the cohort when IOPTH was utilised were determined. Differences between groups were evaluated with Chi-squared and Fisher's exact test. Between January 2004 and September 2018, 849 patients (75.4% women), median age 64 years (IQR 54-72), were analysed. The median preoperative adjusted serum calcium was 2.80mmol/l (IQR 2.78-2.90), and the median preoperative PTH was 14.20pmol/l (IQR 10.70-20.25). The overall first-time cure (normocalcaemia) rate was 96.4%. The sensitivity, specificity, positive predictive value and negative predictive values of IOPTH were 96.8%, 83.2%, 97.6% and 78.8%, respectively, with an accuracy of 95.1%. For patients with concordant scans (48.3%), a targeted approach without IOPTH would have achieved a cure rate of 94.1% compared with 98.0% using IOPTH (p<0.01) CONCLUSION: The use of IOPTH assay significantly improved the rate of normocalcaemia at 6 months. The low NNT to benefit from IOPTH, particularly those patients with a single positive scan, and the inevitable reduction in the potential costs incurred from failure and reoperation justify its utilisation.

Evolution of the Diagnosis and Treatment of Primary Hyperparathyroidism.

This study aims to present the evolution of our center's approach to treating primary hyperparathyroidism (PHPT) from diagnosis to intraoperative interventions. We have also evaluated the intraoperative localization benefits of indocyanine green fluorescence angiography. This retrospective single-center study involved 296 patients who underwent parathyroidectomy for PHPT between January 2010 and December 2022. The preoperative diagnostic procedure included neck ultrasonography in all patients, [99mTc]Tc-MIBI scintigraphy in 278 patients, and, in 20 doubtful cases, [18F] fluorocholine positron emission tomography (PET) computed tomography (CT) was performed. Intraoperative PTH was measured in all cases. Indocyanine green has been administered intravenously since 2020 to guide surgical navigation using a fluorescence imaging system. The development of high precision diagnostic tools that can localize an abnormal parathyroid gland in combination with intra-operative PTH assay (ioPTH) enables the surgical treatment of PHPT patients with focused approaches and excellent results that are stackable with bilateral neck exploration (98% of surgical success). Indocyanine green angiography has the potential to assist surgeons in identifying parathyroid glands rapidly and with minimal risk, especially when pre-operative localization has failed. When everything else fails, it is only an experienced surgeon who can resolve the situation.

BIOCHEMICAL WITH NORMAL PARATHYROID HORMONE : A CASE REPORT

Normo-hormonal primary hyperparathyroidism(NPHPT) is an uncommon condition which has been increasing in last decade. This milder biochemical entity remains incompletely understood due to lack of long term health outcomes regarding management. NPHPT poses two challenges to the surgeon, rst is when to operate and second is the use of intra-operative parathyroid hormone assay to predict the success of surgery. Here we present a 53 year old lady who came with low back ache of more than 2 years duration. It is found to have elevated calcium levels and on further evaluation found to have high normal parathyroid hormone levels in two occasions. Pre operative localization studies were done by suspecting normo-hormonal hyperparathyroidism which showed concordant lesions in both ultrasound neck and Sestamibi scan. She underwent focused parathyroidectomy with intra-operative parathyroid hormone levels which dropped in to less than 30pg/ml. Postoperative calcium was within normal limits and she was symptomatically better. In patients with symptoms of hypercalcemia, elevated calcium levels and high normal intact parathyroid hormone levels should be considered as inappropriate and should lead to the suspicion of normo-hormonal hyperparathyroidism. Intra operative parathyroid hormone levels below 30pg/ml can be utilized as an indicator of successful operation in normo-hormonal hyperparathyroidism.In symptomatic hypercalcemic patients, even if the parathyroid hormones are high normal, a further investigation should be done to locate the parathyroid adenoma and surgery is the best cure

PSAT205 A Case of Persistent Primary Hyperparathyroidism Secondary to an Occult Supernumerary Parathyroid Adenoma

Abstract Background Persistent primary hyperparathyroidism accounts for the vast majority of patients who require reexploration. With the advancements in preoperative localization, surgical outcomes have improved over time. However, in patients with failed reoperative parathyroid exploration, an occult supernumerary parathyroid adenoma should be considered. Clinical Case A 60 year-old female diagnosed with primary hyperparathyroidism presented with recurrent nephrolithiasis, osteoporosis and declining eGFR. Initial laboratory evaluation showed elevated serum calcium (1.54 mmol/L, normal 1.09-1.30) and intact PTH (146 pg/mL, normal 18.50-88.0). 99mTc-sestamibi scintigraphy showed a sestamibi-avid focus in the inferior aspect of the right lobe hence, she underwent radionuclide-guided focused right parathyroidectomy. Post-operatively, her intact PTH level was still elevated (171.2 pg/mL). Histopathologic examination showed a normocellular parathyroid gland and a multifocal papillary thyroid carcinoma. The failed 1st surgery was attributed to the false positive scintigraphy from the papillary thyroid carcinoma. She then underwent total thyroidectomy with central neck dissection and 3½ parathyroidectomy with intraoperative parathyroid hormone assay. However, serial PTH monitoring after exploration and parathyroidectomy failed to decrease the PTH level by 50%. Histopathologic examination showed normocellular parathyroid glands. The bilateral carotid sheath, retropharyngeal region and superior mediastinum were explored but no ectopic parathyroid tissues were seen. Post-operatively, calcium and PTH were still elevated (1.48 mmol/L and 200.5 pg/mL, respectively). FDG PET CT imaging failed to show any ectopic parathyroid gland or adenoma. No further surgical intervention was done and she was medically managed with Cinacalcet 30 mg twice daily. 15 months after her parathyroid gland exploration, calcium and PTH were still elevated (1.46 mmol/L and 156.80 pg/mL, respectively). F18 Choline PET CT imaging was done showing a small hypoenhancing persistently FCH-positive focus in the left thyroid bed and sliver of enhancing tissue relating to a parathyroid adenoma. Conclusion This case highlights the diagnostic and therapeutic challenges in a patient with persistent primary hyperparathyroidism after a failed 2nd surgery. Occult parathyroid adenomas can cause significant symptoms regardless of its size and its imperceptible nature on imaging. The role of medical management is emphasized in this case when surgical management was not possible. Furthermore, re-evaluation for growth of the possible occult parathyroid adenoma should be done, which in this case took 15 months until its detection. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

A giant parathyroid adenoma mimicking a thyroid swelling: A case report

Giant parathyroid adenomas are uncommon. Its clinical management is challenging. Our study’s goal is to share our experience with pre-operative localization of parathyroid adenomas while emphasizing the importance of intraoperative parathyroid hormone (IOPTH) assays in such situations. Here, we present the case of a 46-year-old woman who was diagnosed with parathyroid adenoma. The clinical aspects, pre-operative management, and surgical procedure have all been examined. Parathyroid hormone levels were reduced by 90% following surgical removal of the tumor and an IOPTH assay. IOPTH significantly improves surgical success rates in patients with only one positive imaging test result and adds significant value to surgical decision-making.

Role and Recent Trend of Intraoperative Parathyroid Hormone Monitoring During Parathyroidectomy in Patients With Primary Hyperparathyroidism

In the last few decades, the standard surgical treatment for primary hyperparathyroidism (PHPT) has shifted from bilateral neck exploration to focused/minimally invasive parathyroidectomy (FMIP). This shift was accelerated by the introduction of intraoperative parathyroid hormone (IOPTH) monitoring, which can provide intraoperative information regarding the localization and complete excision of the pathological parathyroid gland during FMIP. Since the first clinical application of the IOPTH assay in 1991, IOPTH monitoring has substantially improved to date to increase its performance and availability. In addition, the clinical applications of IOPTH changed with the needs of actual clinical practice, although the fundamental concept and technique remained unchanged. In this review, we discuss the role of IOPTH monitoring in the surgical management of PHPT based on the results of contemporary studies and summarized the major issues regarding IOPTH.

Localization of Ectopic Mediastinal Parathyroid Adenomas Using Indigo Carmine Injection for Surgical Management: A Preliminary Report.

An ectopic parathyroid adenoma (EPA) is a rare entity. The aim of this study was to report our experience in the preoperative localization and surgical management of EPAs. This was a multicenter retrospective study involving patients diagnosed with an EPA (three males and seven females) from January 2005 to November 2021. The clinical features, preoperative management, and surgical procedures were analyzed. A cervical neck ultrasound was performed in all patients and showed a focus in eight patients. Cervicothoracic enhanced computed tomography was performed in all patients and showed a focus in nine patients. The 99mTc-MIBI scintigraphy was performed in eight patients and showed uptake in six of them. We performed a neck dissection and thoracotomy in one patient, a thoracoscopy in one patient, surgery with a focused approach in seven patients, four of whom were injected with indigo carmine blue, and surgery with a bilateral approach in one patient. 1 h following the parathyroidectomy, the parathyroid hormone (PTH) concentration was decreased to 40–80% of the baseline value. Establishing a preoperative diagnosis of an EPA is challenging for the surgeon, despite the progress in the morphologic assessment. An intraoperative PTH assay and injection of indigo carmine have been shown to be valuable tools in the appropriate surgical management of an EPA.

Test Minimally Invasive Parathyroidectomy Under Local Cervical Block Anesthesia for Primary Hyperparathyroidism and Parathyroid Adenoma

With both improvement in preoperative parathyroid tumor identification and the use of intraoperative parathyroid hormone (PTH) assay, minimally invasive parathyroidectomy (MIP) is now performed more frequently in patients with primary hyperparathyroidism (pHPT) compared to both historically and to cervical exploration. Still, many institutions are not familiar with performing MIP under regional or local anesthesia. We present such an operation under local cervical block anesthesia.

Indocyanine Green Angiography of Parathyroid Glands versus Intraoperative Parathyroid Hormone Assay as a Reliable Predictor for Post Thyroidectomy Transient Hypocalcemia

Background Prediction of postoperative hypocalcemia is a fundamental issue in thyroidectomy. Indocyanine green (ICG) angiography of parathyroid glands is a feasible method to detect the perfusion of parathyroid glands and predict postoperative hypocalcemia. Materials and Methods A prospective observational study was conducted at Ain Shams University Hospitals between April 2018 and April 2021. The included cases of total thyroidectomy underwent intraoperative ICG fluorescence angiography to identify the four parathyroid glands and score each gland according to the viability. Patients in which less than four glands were identified were excluded. Intraoperative intact parathyroid hormone (ioPTH) level assay was also measured to compare with ICG in predicting postoperative transient hypocalcemia. Results A total of 134 cases underwent total thyroidectomy during the study period. We could identify the four parathyroid glands in 90 patients, including them in the study. We had postoperative hypocalcemia in 28 cases (31.1%). The diagnostic accuracy of ICG angiography and ioPTH level assay was high and almost similar (82.22% versus 87.78%). Both were higher than the surgeons’ diagnostic accuracy of visual inspection (62.22%). Conclusions ICG angiography of the parathyroid gland is a safe, reliable predictor for postoperative transient hypocalcemia with a high and almost similar accuracy compared to intraoperative parathyroid hormone level.

New, simple, fast, whole blood Intraoperative PTH assay – Laboratory and Clinical validation

Abstract Introduction IOPTH monitoring is a reliable method of predicting cure during the surgery for Primary Hyperparathyroidism (PHPT) but current methods are slow and require presence of laboratory staff. NBCL Connect is the first Analyser which can be used by theatre staff and measures whole blood PTH in 5 minutes. Aim Laboratory and Clinical validation of new IOPTH assay in patients undergoing surgery for PHPT. Methods Intra and inter assay variability using BioRad Liquichek Specialty Immunoassay, internal quality controls and serum and whole blood PTH concentrations in patients cured by parathyroidectomy for PHPT measured on NBCL and “gold standard” Future Diagnostics (FD) and Roche platforms. Pearson coefficient was used for linear correlation between measurements. Results Preliminary precision data confirms good analytical performance of NBCL Analyser which is similar to that of FD platform. Further precision, accuracy, linearity and sensitivity studies are ongoing. Plasma PTH concentration from 4 patients (5 samples each, total 20) measured on NBCL and FD platforms showed good correlation (R 0.90, slope 0.644, IC – 0.68) Whole blood PTH concentration in 2 patients (5 samples each, total 10) measured on NBCL, FD and Roche platforms showed good correlation. 50% reduction in circulating PTH, main (Miami) criteria confirming biochemical cure, were similar for all 3 platforms Conclusions NBCL Connect Analyser assay showed good laboratory and clinical performance able to predict biochemical cure in patients undergoing surgery for PHPT. Our preliminary data suggests that this straightforward to operate and fast system is a promising technology which can be used widely during parathyroid surgery.

Intraoperative parathyroid hormone assay to guide completion of parathyroid surgery

Intraoperative parathyroid hormone assay to guide completion of parathyroid surgery

Evaluation of Wisconsin and CaPTHUS Indices Usefulness for Predicting Monoglandular and Multiglandular Disease in Patients with Primary Hyperparathyroidism through the Analysis of a Single-Center Experience.

Background The main challenge for treating primary hyperparathyroidism (PHPT) is to understand if it is caused by a single adenoma (80–85% of the cases) or by a multiglandular disease (15–20%), both preoperatively and intraoperatively. For this reason, some preoperative scores were proposed in the literature, to perform focused parathyroidectomy, avoiding intraoperative parathormone assay (ioPTH). The most known are the CaPTHUS test and the Wisconsin index. We applied them to our experience. Methods A retrospective cohort study on 462 patients referred for parathyroidectomy to Thyroid and Parathyroid Unit at Santi Paolo e Carlo Hospital, Milan, Italy, from 2011 to 2021. Only patients affected with benign PHPT and neck ultrasound performed at our institution were included. Both patients for whom preoperative imaging agreed with the localization of a single diseased parathyroid and those with only ultrasound or scintigraphy positive for parathyroid localization underwent Mini-Invasive Video-assisted parathyroidectomy. In all cases, ioPTH assay was performed. The conversion to bilateral neck exploration was decided based on the drop in ioPTH. CaPTHUS score and the Wisconsin index (Win) were applied to the series. CaPTHUS score ≥3 and Win index >1600, according to the original studies of the literature, were considered at high probability of monoglandular disease. Outcomes in these two groups were examined. Results 236 patients were eligible for the study. The pathology resulted in multiglandular disease in 24 patients (10.2%). Among these, 18 (75.0%) obtained a CaPTHUS score ≥3, and 20 (83.3%) had a Win index>1600. Intraoperative PTH allowed to identify multiglandular disease in 16 of 18 cases with CaPTHUS ≥3 and in 18 of 20 cases with win >1600, who could have been lost, based only on the results of these 2 tests. Conclusion Based on our experience, CaPTHUS test and Wisconsin index were not so useful in predicting multiglandular disease as ioPTH.

A RARE CASE OF MAXILLARY BROWN TUMOUR AS PRIMARY PRESENTATION OF THE PARATHYROID CARCINOMA.

Background: Brown tumours are expansile osteolytic lesions of bone, occurring in Hyperparathyroidism. Brown tumours occur most commonly in ribs, clavicle, long bones and pelvis and are uncommon in other facial bones except mandible. Other facial bones are rarely affected. Brown tumors are due to the direct effect of the parathyroid hormone. Brown tumors occur more with primary hyperparathyroidism than secondary. However, they are reported more in secondary hyperparathyroidism. In primary hyperparathyroidism, a parathyroid adenoma is a cause in 81% while other causes include hyperplasia in 15% and parathyroid carcinoma only in 4%. We present a case report of maxillary Brown tumor due to parathyroid carcinoma in an elderly male patient. Case Report: A 67-year-old male presented with right maxillary swelling increasing in size for the last few months associated with ipsilateral nasal block and right eye epiphora. The contrast CT scan of paranasal sinuses and neck revealed a large expansile right maxillary tumor aggressively eroding maxillary wall with extension into the orbital oor, ethmoid, sphenoid sinuses, nasal cavity, and oral cavity with the erosion of hard palate and soft tissue extension to subcutaneous Plane. A three cm sized soft tissue density lesion was also noted posterior to the right thyroid lobe in CT sections of the neck. Blood prole was normal except extremely high serum parathormone and calcium as well as mildly elevated serum creatinine (S. PTH 3437 pg./ml. S. Ca. 19 mg%. S. Creatinine 1.77mg%.) Ultrasonography of the abdomen also revealed calcication in the renal medulla. Right lower parathyroidectomy was done with the frozen section as well as the Intraoperative Rapid PTH assay. The PTH level was reduced by 90 percent of the original value. The nal histopathology was suggestive of parathyroid carcinoma. Summary: The patient was under regular surveillance, as the maxillary tumor was under remittance after the resection of parathyroid carcinoma. Parathyroid carcinoma is a very rare tumor and involvement of maxillary bone due to primary hyperparathyroidism due to parathyroid carcinoma is also uncommon.

A Case of an Ectopic Parathyroid Adenoma With a Concomitant 99mTc-sestamibi-avid Papillary Thyroid Carcinoma

Background: The evaluation and management of parathyroid adenomas have improved over the years. Localization of parathyroid adenomas in patients with primary hyperparathyroidism was simplified with the use of 99mTc-sestamibi scintigraphy. In the advent of minimally invasive parathyroid surgery, use of radionuclide probes reduced the need for neck exploration and intraoperative frozen section leading to fewer complications, shorter operative time and hospitalization and rapid postoperative recovery. However, limitations of these techniques should be taken into consideration in certain cases. Clinical Case: A 60 year-old female diagnosed with primary hyperparathyroidism presented with recurrent nephrolithiasis and osteoporosis. Initial laboratory evaluation showed elevated serum calcium and intact PTH (1.54 mmol/L and 146 pg/mL, respectively). 99mTc-sestamibi scintigraphy showed a sestamibi-avid focus in the inferior aspect of the right lobe suggestive of a parathyroid adenoma or hyperplasia. Pre-operative neck ultrasound showed non-specific thyroid parenchymal changes and nodules on both lobes with benign sonographic features. She underwent radionuclide-guided focused right parathyroidectomy. The identified enlarged right inferior parathyroid gland registered a highest reading of 70 cps on radionuclide probe. Post-operatively, repeat intact PTH level was still elevated (171.2 pg/mL). There was an interval non-demonstration of the sestamibi-avid focus in the inferior aspect of the right thyroid lobe with an increased sestamibi uptake in the left thyroid lobe compared to the previous parathyroid scan. Histopathologic examination showed a normocellular parathyroid gland and a multifocal papillary thyroid carcinoma. She underwent total thyroidectomy with central neck dissection and 4 parathyroid gland exploration with intraoperative parathyroid hormone assay. However, serial PTH monitoring after left inferior parathyroidectomy and after bilateral partial superior parathyroidectomy still showed elevated levels. Histopathologic examination showed mildly enlarged, normocellular parathyroid gland. The bilateral carotid sheath, retropharyngeal region and superior mediastinum were explored but no ectopic parathyroid tissues were seen. Post-operatively, calcium and PTH were still elevated (1.48 mmol/L and 200.5 pg/mL, respectively). Conclusion: This case highlights the predicaments in the management of parathyroid adenomas, recognizing the possibility of false-positive sestamibi scans due to malignant thyroid nodules and the possibility of the two diseases occurring concurrently, albeit rare.

O62: INTRA-OPERATIVE ADJUNCTS IN MINIMALLY INVASIVE RADIO-GUIDED PARATHYROIDECTOMY AT A SPECIALIST ENDOCRINE SURGERY CENTRE

Abstract Introduction Primary Hyperparathyroidism (PH) is common cause of hypercalcaemia (0.3% of the population). Minimally invasive radio-guided parathyroidectomy (MIRP) has been made possible due to advancements in pre-operative imaging i.e. sestamibi scans allowing localisation of areas of parathyroid hyperactivity. Method Due to the disagreement in the literature regarding which intra operative adjunct is best used in MIRP surgery to decrease recurrence, the rationale for this study is to examine and compare the performance of these adjuncts in consecutive patients i.e. 1. Intra operative PTH assay (IOPTHA) 2. Tc-99m radio-guidance using a gamma probe and the 20% rule 3. Frozen section analysis. Result 45 MIRP procedures were carried out between 01/07/2018 and 30/10/2019. 77.8% were females; mean age was 62 years (range 30 - 79). Final pathology showed that in 43 of the cases parathyroid tissue was correctly removed; thyroid tissue was identified for the other 2 cases. 20% rule was positive in 43 out of the 45 cases and negative in 2 (sensitivity 100%, specificity 100%). A drop in IOPTHA greater than 50% was found in 41 out of the 45 cases but not in 4 (sensitivity 93.9%, specificity 100%). Frozen section was 100% concordant with final pathology (45/45). AUC analysis showed no significant difference in the performance of these tests (p = 0.15) but was around 1 for 20% rule and Frozen section. Conclusion When radio-guidance and frozen sections are added to IOPTHA, the success rate of parathyroidectomy is markedly improved. Using them together will greatly reduce recurrent hyperparathyroidism. Take-home message When radio-guidance and frozen sections are added to Intra-operative PTH assays in Minimally Invasive Radio-Guided Parathyroidectomy, the success rate of parathyroidectomy is markedly improved. Using them together as in our study will greatly reduce the incidence of recurrent hyperparathyroidism and thus recurrent surgery.

A Rapid Intraoperative Parathyroid Hormone Assay Based on the Immune Colloidal Gold Technique for Parathyroid Identification in Thyroid Surgery.

ObjectiveA novel immunochromatographic test strip method was developed to detect tissue parathyroid hormone (PTH) using the immune colloidal gold technique (ICGT). The accuracy and application value of this method for intraoperative parathyroid identification were evaluated.MethodsSerum samples were collected to measure PTH by both ICGT and electrochemiluminescence immunoassay (ECLIA). Patients who underwent unilateral and total thyroidectomy were enrolled to evaluate the feasibility and clinical efficacy of rapid intraoperative identification of parathyroid glands via PTH determination using ICGT. Two sample preparation methods, fine needle aspiration (FNA) and tissue block homogenate (TBH), were used for PTH-ICGT analysis.ResultsBablok analysis showed a linear relationship between the serum PTH measurements obtained by ICGT and ECLIA. Non-parathyroid tissues had much lower PTH concentrations (14.8 ± 2.1 pg/ml, n = 97) detected by ICGT, compared to the parathyroid gland tissues (955.3 ± 16.1 pg/ml, n = 79; P < 0.0001), With biopsy results as the standard, ICGT showed higher diagnosis rates as compared with direct visual inspection, for identifying both parathyroid glands (97.4 vs. 78.2%) and non-parathyroid tissues (100 vs. 68.9%). The cut-off values for parathyroid identification by FNA and TBH methods were 63.99 and 136.30 pg/ml, respectively. The detection time was 2 min by TBH method for in vitro tissue detection and 6 min by FNA method for in situ tissue detection, both of which were faster than traditional intraoperative cryopathological examination (usually >30 min). Intraoperative application of ICGT method was associated with higher postoperative serum calcium and blood PTH levels at 1 and 3 months as well as a lower incidence of postoperative transient hypocalcemia, as compared with direct visual inspection.ConclusionPTH-ICGT assay shows high potential as a rapid, novel alternative for intraoperative parathyroid identification.