Effects of Parathyroidectomy on Normocalcemic Primary Hyperparathyroidism and the Role of Intraoperative PTH Measurement

Background Normocalcemic primary hyperparathyroidism (NCpHPT) and normohormonal primary hyperparathyroidism (NHpHPT) are recently recognized variants of primary hyperparathyroidism. Current guidelines for the management hyperparathyroidism recognize NCpHPT as one of the areas that are recommended for more research due to limited available data. Methods A retrospective review of patients who had parathyroidectomy between 2014 and 2019. We excluded patients with multiple endocrine neoplasia syndromes and secondary and tertiary hyperparathyroidism. Included patients were classified based on the biochemical profile into classic or normocalcemic hyperparathyroidism group. Collected data included demographics, preoperative localizing imaging, intraoperative parathyroid hormone levels, and postoperative cure rates. Results 261 patients were included: 160 patients in the classic and 101 patients in the normocalcemic group. Patients in the normocalcemic group had significantly more negative sestamibi scans (n = 58 [8.2%] vs 78 [51.3%], P = <.01), smaller parathyroid glands (mean weight 436.0 ± 593.0 vs 742.4 ± 1109.0 mg, P = .02), higher parathyroid hyperplasia rates (n = 51 [50.5%] vs 69 [43.1%]), and significantly higher intraoperative parathyroid hormone at 10 minutes (78.1 ± 194.6 vs 43.9 ± 62.4 1, P = .04). Positive predictive value of both intraoperative parathyroid hormone and cure rate was lower in the normocalcemic group (84.2% vs 95.7%) and (80.5% vs 95%), respectively. Conclusion Normocalcemic hyperparathyroidism is a challenging disease. Surgeons should be aware of the lower cure rate in this group, interpret intraoperative parathyroid hormone with caution, and have a lower threshold for bilateral neck exploration and 4 glands visualization.

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.

920 Improving the Management of Post-Operative Hypocalcaemia In Thyroid Surgery

Aim Hypocalcaemia is a frequent, and potentially dangerous, complication of total thyroidectomy [1, 2] due to the removal of the parathyroid glands. This quality improvement (QI) project was undertaken in a large Ear, Nose and Throat department in the East of England over a year. The project improved postoperative guideline compliance by optimising the recognition and management of patients at risk of hypocalcaemia. This process focussed on improving parathyroid hormone (PTH) and calcium blood testing, appropriate prescribing and the monitoring and management of hypocalcaemia. Method A baseline audit was conducted to determine initial guideline compliance. The QI process subsequently involved the introduction of a new intraoperative PTH pathway and the amendment of trust guidelines. In addition, there was a focus on improving clinician awareness of guidelines, junior doctor education, communication between operating surgeons and junior doctors and the optimisation of patient handover. Results The measurement of PTH at four hours improved from 42.5% to 52.2%. The project saw a significant improvement in the monitoring of hypocalcaemia (from 22.2% to 83.3% for patients with an intermediate risk of hypocalcaemia) and in the prescribing of prophylactic calcium supplements from 7.5% to 43.5%. Conclusions By optimising postoperative care this QI project improved patient safety as well as impacting on the duration, and overall cost, of inpatient stay.

The Usefulness of Intraoperative PTH as a Predictor for Successful Parathyroidectomy in Secondary Hyperparathyroidism

Introduction: Secondary hyperparathyroidism (SHPT) is a multisystemic syndrome that affects calcium and bone homeostasis in patients with chronic kidney disease (CKD). Despite medical treatment, 1–2% of patients require parathyroidectomy annually. The use of an intraoperative parathormone protocol (IOPTH) to predict cure is still in debate, due to the lack of standardized protocols, the use of different assays, and uneven PTH clearance. This study aimed to determine the diagnostic accuracy of an IOPTH in patients with SHPT for predicting successful surgery after parathyroidectomy.Methods: About 30 patients were enrolled. A prospective observational study (cohort) was performed in patients who were submitted to parathyroidectomy by an endocrine surgeon for SHPT. All were submitted to a bilateral neck exploration with a subtotal parathyroidectomy. Three IOPTH determinations were withdrawn: at anesthetic induction (PTH0), 15 min (PTH15), and 30 min (PTH30) after completion of gland resection. Another sample was taken 24 h after the procedure (PTH24), values &lt;150 pg/mL defined a successful surgery, and patients were assigned to the success or failure group. IOPTH drop was analyzed to predict successful surgery with drops of 70 and 90% at 15 and 30 min, respectively.Results: A total of 26 patients were included, 19 patients were in the successful group. IOPTH showed a significant difference between groups in their absolute PTH15 and PTH30 values. A significant difference was also found in their PTH drop at 30 min (81 vs. 91%, p = 0.08). For predicting a successful surgery, having a PTH drop &gt;90% at 30 min was the most significant factor [Odds Ratio (OR) 3.0 (1.5–4) IC 95%].Conclusions: This study points toward a stricter and staggered IOPTH protocol to predict a successful surgery. Our results suggest taking a PTH15 expecting a PTH drop of &gt;90%. If this is not achieved, reexploration and a PTH30 sample are suggested to accurately predict success.

Miami Criterion for Recurrent Men-1 Related Hyperparathyroidism in the Forearm

BackgroundTotal parathyroidectomy with autotransplantation of parathyroid tissue to the forearm is one of the treatment modalities for primary hyperparathyroidism (PHPT) in multiple endocrine neoplasia type 1 (MEN 1). Recurrence rate with this approach has been documented in up to 35% of patients. The amount of tissue to be preserved during autograft debulking has not been well established.MethodsPreoperative assessment begins with biochemical confirmation of recurrent PHPT. Anatomic and functional imaging must be obtained. Intraoperative PTH monitoring is used to evaluate adequate amount of parathyroid tissue to be debulk pursuing more than 50% of PTH drop.ResultsOne patient with recurrent MEN1 related PHPT successfully underwent autograft debulking using the Miami criterion to assess adequate resection. The postoperative course was uneventful and on follow up the patient did not develop hypoparathyroidism.ConclusionThe use of Miami criterion during autograft debulking reoperations in the setting of MEN-1 is a feasible tool to achieve remission of primary hyperparathyroidism.

37 Improving the Management of Post-Operative Hypocalcaemia in Thyroid Surgery

Introduction Hypocalcaemia is a frequent, and potentially dangerous, complication of total thyroidectomy [1, 2]. This quality improvement (QI) project was undertaken in a large ENT department in the East of England over a year. The project improved postoperative guideline compliance by optimising the recognition and management of patients at risk of hypocalcaemia. This process focussed on improving parathyroid hormone (PTH) and calcium blood testing, appropriate prescribing and the monitoring and management of hypocalcaemia. Method Following a baseline audit the QI process subsequently involved the introduction of a new intraoperative PTH pathway and the amendment of trust guidelines. In addition, there was a focus on improving clinician awareness of guidelines, junior doctor education, communication between operating surgeons and junior doctors and the optimisation of patient handover. Results The measurement of PTH at four hours improved from 42.5% to 52.2%. The project saw a significant improvement in the monitoring of hypocalcaemia (from 22.2% to 83.3% for patients with an intermediate risk of hypocalcaemia) and in the prescribing of prophylactic calcium supplements from 7.5% to 43.5%. Conclusions By optimising postoperative care this QI project improved patient safety as well as impacting on the duration, and overall cost, of inpatient stay.

Incidentally discovered severe hypercalcaemia from a functioning parathyroid cyst: the limitations of intraoperative parathyroid hormone (IOPTH) monitoring

Parathyroid cysts (PCs) are rare pathologies and are typically non-functional (do not secrete parathyroid hormone (PTH)). The aetiology of PCs is highly debated, and management is complex. We present a unique case of a parathyroid adenoma contained within a functional PC and highlight the limitations of intraoperative PTH monitoring during the surgical resection of functional PCs.

[18F]fluoro-ethylcholine-PET Plus 4D-CT (FEC-PET-CT): A Break-Through Tool to Localize the “Negative” Parathyroid Adenoma. One Year Follow Up Results Involving 170 Patients

Background: The diagnostic performance of [18F]fluoro-ethylcholine-PET-CT&4D-CT (FEC-PET&4D-CT) to identify parathyroid adenomas (PA) was analyzed when ultrasound (US) or MIBI-Scan (MS) failed to localize. Postsurgical one year follow-up data are presented. Methods: Patients in whom US and MS delivered either incongruent or entirely negative findings were subjected to FEC-PET&4D-CT and cases from July 2017 to June 2020 were analyzed, retrospectively. Cervical exploration with intraoperative PTH-monitoring (IO-PTH) was performed. Imaging results were correlated to intraoperative findings, and short term and one year postoperative follow-up data. Results: From July 2017 to June 2020 in 171 FEC-PET&4D-CTs 159 (92.9%) PAs were suggested. 147 patients already had surgery, FEC-PET&4D-CT accurately localized in 141; false neg. 4, false pos. 2, global sensitivity 0.97; accuracy 0.96, PPV 0.99. All of the 117 patients that already have completed their 12-month postoperative follow up had normal biochemical parameter, i.e., no signs of persisting disease. However, two cases may have a potential for recurrent disease, for a cure rate of at least 98.3%. Conclusion: FEC-PET&4D-CT shows unprecedented results regarding the accuracy localizing PAs. The one-year-follow-up data demonstrate a high cure rate. We, therefore, suggest FEC-PET-CT as the relevant diagnostic tool for the localization of PAs when US fails to localize PA, especially after previous surgery to the neck.