Contribution of intraoperative parathyroid hormone monitoring to the surgical success in minimal invasive parathyroidectomy

Is intraoperative parathyroid monitoring during minimally invasive parathyroidectomy still justified?

Introduction

Primary hyperparathyroidism (PHPT) is the third most common endocrine disease. With parathyroidectomy, a cure rate of over 95% at initial surgery is reported. Localization of the abnormal parathyroid gland is critical for the operation to be successful. The aim of this study is to analyze data of patients with single gland disease (SGD) and positive concordant localization imaging undergoing minimally invasive parathyroidectomy (MIP) and intraoperative parathyroid hormone monitoring (IOPTH) to evaluate if IOPTH is still justified in patients with localized SGD.

Methods

A retrospective database analysis of all minimally invasive operations with IOPTH for PHPT and positive concordant localization in ultrasound (US) and 99mTc-sestamibi scintigraphy (MIBI) between 2016-2021. When both US and MIBI were negative, patients underwent either choline or methionine PET-CT. The patients were also analyzed a second time without applying IOPTH.

Results

In total, 198 patients were included in the study. The sensitivity of US, MIBI and PET-CT was 96%, 94% and 100%, respectively. Positive predictive value was 88%, 89% and 94% with US, MIBI and PET-CT, respectively. IOPTH was true positive in 185 (93.4%) patients. In 13 (6.6%) patients, no adequate IOPTH decline was observed after localizing and extirpating the assumed enlarged parathyroid gland. Without IOPTH, the cure rate decreased from 195 (98.5%) to 182 (92%) patients and the rate of persisting disease increased from 2 (1.0%) to 15 (7.5%) patients.

Conclusion

Discontinuing IOPTH significantly increases the persistence rate by a factor of 7.5 in patients with concordantly localized adenoma. Therefore, IOPTH appears to remain necessary even for this group of patients.

Pitfalls of DualTracer 99m-Technetium (Tc) Pertechnetate and Sestamibi Scintigraphy before Parathyroidectomy: Between Primary-Hyperparathyroidism-Associated Parathyroid Tumour and Ectopic Thyroid Tissue

Diagnosis of primary hyperparathyroidism (PHP) is based on blood assessments in terms of synchronous high calcium and PTH (parathormone), but further management, particularly parathyroid surgery that provides the disease cure in 95-99% of cases, requires an adequate localisation of the parathyroid tumour/tumours as the originating source, with ultrasound and 99m-Technetium (99m-Tc) sestamibi scintigraphy being the most widely used. We aimed to introduce an adult female case diagnosed with PHP displaying unexpected intra-operatory findings (ectopic thyroid tissue) in relation to concordant pre-operatory imaging modalities (ultrasound + dual-phase 99m-Tc pertechnetate and sestamibi scintigraphy + computed tomography) that indicated bilateral inferior parathyroid tumours. A sudden drop in PTH following the removal of the first tumour was the clue for performing an extemporaneous exam for the second mass that turned out to be non-malignant ectopic thyroid tissue. We overviewed some major aspects starting from this case in point: the potential pitfalls of pre-operatory imaging in PHP; the concordance/discordance of pre-parathyroidectomy localisation modalities; the need of using an additional intra-operatory procedure; and the clues of providing a distinction between pathological parathyroids and thyroid tissue. This was a case of adult PHP, whereas triple localisation methods were used before parathyroidectomy, showing concordant results; however, the second parathyroid adenoma was a false positive image and an ectopic thyroid tissue was confirmed. The pre-operatory index of suspicion was non-existent in this patient. Hybrid imaging modalities are most probably required if both thyroid and parathyroid anomalies are suspected, but, essentially, awareness of the potential pitfalls is mandatory from the endocrine and surgical perspectives. Current gaps in imaging knowledge to guide us in this area are expected to be solved by the significant progress in functional imaging modalities. However, the act of surgery, including the decision of a PTH assay or extemporaneous exam (as seen in our case), represents the key to a successful removal procedure. Moreover, many parathyroid surgeons may currently perform 4-gland exploration routinely, precisely to avoid the shortcomings of preoperative localisation.

Update on the current management of persistent and recurrent primary hyperparathyroidism after parathyroidectomy

Primary hyperparathyroidism (pHPT) is the third most common endocrine disease. The surgical procedure aims for permanent cure, but recurrence has been reported in 4%-10% of pHPT patients. Preoperative localization imaging is highly valuable. It includes ultrasound, computed tomography (CT), single-photon-emission CT, sestamibi scintigraphy and magnetic resonance imaging. The operation has been defined as successful when postoperative continuous eucalcemia exists for more than the first six months. Ongoing hypercalcemia during this period is defined as persistence, and recurrence is defined as hypercalcemia after six months of normocalcemia. Vitamin D is a crucial factor for a good outcome. Intraoperative parathyroid hormone (PTH) monitoring can safely predict the outcomes and should be suggested. PTH ≤ 40 pg/mL or the traditional decrease ≥ 50% from baseline minimizes the likelihood of persistence. Risk factors for persistence are hyperplasia and normal parathyroid tissue on histopathology. Risk factors for recurrence are cardiac history, obesity, endoscopic approach and low-volume center (at least 31 cases/year). Cases with double adenomas or four-gland hyperplasia have a greater likelihood of persistence/ recurrence. A 6-mo calcium > 9.7 mg/dL and eucalcemic parathyroid hormone elevation at 6 mo may be associated with recurrence necessitating long-term follow-up. 18F-fluorocholine positron emission tomography and 4-dimensional CT in persistent and recurrent cases can be valuable before reoperation. With these novel advances in preoperative imaging and localization as well as intraoperative PTH measurement, the recurrence rate has dropped to 2.5%-5%. Six-month serum calcium ≥ 9.8 mg/dL and parathyroid hormone ≥ 80 pg/mL indicate a risk of recurrence. Negative sestamibi scintigraphy, diabetes and elevated osteocalcin levels are predictors of multiglandular disease, which brings an increased risk of persistence and recurrence. Bilateral neck exploration was considered the gold-standard diagnostic method. Minimally invasive parathyroidectomy and neck exploration are both effective surgical techniques. Multidisciplinary diagnostic and surgical management is required to prevent persistence and recurrence. Long-term follow-up, even up to 10 years, is necessary.

The Role of Bilateral Neck Exploration for Primary Hyperparathyroidism in the Minimally Invasive Parathyroidectomy Era

Objectives

In recent years, together with the contribution of new imaging methods, minimally invasive parathyroidectomy (MIP) has become the standard procedure in selected patients with the primary hyperparathyroidism (pHPT). However, some patients may still need bilateral neck exploration (BNE). In this study, we aimed to evaluate the factors associated with the necessity of BNE.

Methods

Data of the patients, operated by same single surgeon in between 2010 and 2019, were evaluated retrospectively. Patients were divided into two groups as MIP group (group 1) and BNE group (group 2). The risk factors associated with necessity of BNE were evaluated.

Results

Three hundred and forty-four patients (288 females and 56 males) were included in study. The mean age was 54.1±12.8. Pre-operative parathormone level (288 pg/mL vs. 190 pg/mL, p<0.001; respectively), compatible, inconsistent and negative imaging on scintigraphy (82.5% vs. 28.7%, 9.6% vs. 19.1, 7.9% vs. 52.25%, p<0.001; respectively), compatible, inconsistent and negative imaging in ultrasonography (USG) (72.9% vs. 20%, 7% vs. 19.1%, 20.1% vs 60.9%, p<0.001; respectively) in combination of USG and scintigraphy, two positive, single positive and negative imaging (72.5% vs. 11.3%, 25.8% vs. 55.7%, 1.7 vs. 33%, p<0.001; respectively), single adenoma, double adenoma, hyperplasia rates in pathology (96.1% vs. 79.1%, 3.1% vs. 12.2%, 0.9% vs. 8.7%, p<0.001; respectively), concomitant thyroidectomy (11.4% vs. 38.3%, p<0.001; respectively), diameter of the removed gland (2.03 vs. 1.58 cm, p<0.001; respectively), and volume of the removed gland (2.27 vs. 1.22 cm³, p<0.001; respectively), were significantly different in group 1 compared to group 2. Low pre-operative parathormone, discordant pathological gland localization compared to pathological gland compatible with scintigraphy images (odds ratio [OR]: 3.690; p=0.027), negative scintigraphy images (OR: 9.174, p=0.000), and need for additional thyroidectomy (OR: 5.067); p=0.000) were determined as independent risk factors increasing the need for BNE in the multinomial logistic regression analysis. Long-term cure rates were similar (98.3% vs. 94.8%, p=0.079; respectively).

Conclusion

At present, BNE may be necessary in the surgical treatment of a significant proportion of patients with pHPT. According to our results, the possibility of BNE requirement is higher in patients with low PTH level compared to pre-operative high PTH values, in patients with discordant and negative scintigraphy compared to positive and compatible scintigraphy, and in patients who will undergo additional thyroidectomy. We think that BNE is not an alternative to MIP, but an effective option that is complementary to MIP to achieve optimal results in parathyroid surgery.