The Weight of the Resected Gland Predicts Rate of Success After Image-Guided Focused Parathyroidectomy

A contemporary analysis of the pre- and intraoperative recognition of multigland parathyroid disease

BACKGROUND

Despite advances in biochemical and radiological identification of parathyroid gland enlargement, primary hyperparathyroidism (PHPT) due to sporadic multigland parathyroid disease (MGPD) remains a perioperative diagnostic dilemma. Failure to recognise MGPD pre- or intraoperatively may negatively impact surgical cure rates and result in persistent PHPT and ongoing patient morbidity.

METHODS

We have conducted a comprehensive review of published literature in attempt to determine factors that could aid in reliably diagnosing sporadic MGPD pre- or intraoperatively. We discuss preoperative clinical features and examine pre- and intraoperative biochemical and imaging findings concentrating on those areas that give practicing surgeons and the wider multi-disciplinary endocrine team indications that a patient has MGDP. This could alter surgical strategy.

CONCLUSION

Biochemistry can provide diagnosis of PHPT but cannot reliably discriminate parathyroid pathology. Histopathology can aid diagnosis between MGPD and adenoma, but histological appearance can overlap. Multiple negative imaging modalities indicate that MGPD may be more likely than a single parathyroid adenoma, but the gold standard for diagnosis is still intraoperative identification during BNE. MGPD remains a difficult disease to both diagnose and treat.

Predicting multigland disease in primary hyperparathyroidism using ultrasound and clinical features

Background

The identification of multigland disease (MGD) in primary hyperparathyroidism (PHPT) patients is essential for minimally invasive surgical decision-making.

Objective

To develop a nomogram based on ultrasound (US) findings and clinical factors to predict MGD in PHPT patients.

Materials and methods

Patients with PHPT who had surgery between March 2021 and January 2022 were consecutively enrolled to this study. Biochemical and clinicopathological data were recorded. US images were analyzed to extract US features for prediction. Logistic regression analyses were used to identify MGD risk factors. A nomogram was constructed based on these factors and its performance evaluated by area under the receiver operating characteristic curve (AUC), calibration curve, Hosmer-Lemeshow tests, and decision curve analysis (DCA).

Results

A total of 102 PHPT patients were included; 82 (80.4%) had single-gland disease (SGD) and 20 (19.6%) had MGD. Using multivariate analyses, MGD was positively correlated with age (odds ratio (OR) = 1.033, 95% confidence interval (CI): 0.190-4.047), PTH levels (OR = 1.001, 95% CI: 1.000-1.002), multiple endocrine neoplasia type 1 (MEN1) (OR = 29.730, 95% CI: 3.089-836.785), US size (OR = 1.198, 95% CI: 0.647-2.088), and US texture (cystic-solid) (OR = 5.357, 95% CI: 0.499-62.912). MGD was negatively correlated with gender (OR = 0.985, 95% CI: 0.190-4.047), calcium levels (OR = 0.453, 95% CI: 0.070-2.448), and symptoms (yes) (OR = 0.935, 95% CI: 0.257-13.365). The nomogram showed good discrimination with an AUC = 0.77 (0.68-0.85) and good agreement in predicting MGD in PHPT patients. Also, 65 points was recommended as a cut-off value, with specificity = 0.94 and sensitivity = 0.50.

Conclusion

US was useful in evaluating MGD. Combining US and clinical features in a nomogram showed good diagnostic performance for predicting MGD.

Surgical Aspects of Primary Hyperparathyroidism

Parathyroidectomy (PTX) is the treatment of choice for symptomatic primary hyperparathyroidism (PHPT). It is also the treatment of choice in asymptomatic PHPT with evidence for target organ involvement. This review updates surgical aspects of PHPT and proposes the following definitions based on international expert consensus: selective PTX (and reasons for conversion to an extended procedure), bilateral neck exploration for non-localized or multigland disease, subtotal PTX, total PTX with immediate or delayed autotransplantation, and transcervical thymectomy and extended en bloc PTX for parathyroid carcinoma. The systematic literature reviews discussed covered (i) the use of intraoperative PTH (ioPTH) for localized single-gland disease and (ii) the management of low BMD after PTX. Updates based on prospective observational studies are presented concerning PTX for multigland disease and hereditary PHPT syndromes, histopathology, intraoperative adjuncts, localization techniques, perioperative management, "reoperative" surgery and volume/outcome data. Postoperative complications are few and uncommon (<3%) in centers performing over 40 PTXs per year. This review is the first global consensus about surgery in PHPT and reflects the current practice in leading endocrine surgery units worldwide. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Variation in parathyroid adenoma size in patients with sporadic, primary hyperparathyroidism: small gland size does not preclude single gland disease

PURPOSE

Small, abnormal parathyroid glands are usually associated with multigland hyperplasia in patients with primary hyperparathyroidism (pHPT). The purpose of this study was to determine the association between parathyroid adenoma size and biochemical cure rates in patients undergoing single gland parathyroidectomy.

METHODS

The study included patients with sporadic pHPT who underwent initial parathyroidectomy and met intraoperative PTH criteria for cure after resection of a single adenoma (SGD). Patients were divided into quartiles (Q1 = smallest) based on gland weight and maximum dimension; cure rates were compared across groups.

RESULTS

A single parathyroid adenoma was removed in 517 patients, with a median gland weight of 500 mg (range 50-11890). Median maximum gland dimension was 15 mm (range 5-55). With median follow-up of 28 months (range 6-81), the biochemical cure rate was 97.1%. There was no difference in cure rate by gland weight (Q1 94.6%, Q2 96.9%, Q3 98.4%, Q4 98.5%, p = 0.217) or maximum gland dimension (Q1 95.6%, Q2 97.6%, Q3 97.1%, Q4 98.2%, p = 0.641). When Q1 patients (by gland weight) were divided by quartile, there was no difference in cure rates (93.1% [50-140 mg]; 95.2% [150-190 mg]; 97.1% [200-230 mg]; 93.3% [240-280 mg]; p = 0.665).

CONCLUSION

For patients with pHPT who underwent single gland parathyroidectomy, there was no difference in cure rates by gland weight or maximum dimension. These data suggest that the removal of parathyroid adenomas as small as 50 mg with an appropriate decline in ioPTH likely represent single gland disease and additional exploration may not be necessary.

Parathyroid 4D-CT in Primary Hyperparathyroidism: Exploration of Size Measurements for Identifying Multigland Disease and Guiding Biochemically Successful Parathyroidectomy

Background: In patients with primary hyperparathyroidism (PHPT), bilateral neck exploration is necessary for multigland disease (MGD), whereas minimally-invasive parathyroidectomy is often preferred for single-gland disease (SGD). An existing system (4D-CT MGD score) for differentiating SGD and MGD using preoperative parathyroid CT considers the size of only the largest candidate lesion. Objective: To assess utility of second-largest lesion size on parathyroid CT for differentiating SGD from MGD, as well as of individual gland size for predicting need for surgical removal, and to derive optimal size thresholds for these purposes. Methods: This retrospective study included patients with PHPT who underwent biochemically successful parathyroidectomy after preoperative parathyroid CT. Clinical radiology reports were reviewed to classify reported candidate parathyroid lesions as low-, intermediate- or high-confidence. Resected hypercellular parathyroid lesions were correlated with clinically reported candidate lesions. Patients were classified as having SGD or MGD using operative and pathology reports, independent of CT findings. One observer retrospectively determined estimated volume (0.52 x length x width x height) and maximum diameter of clinically reported high-confidence lesions, as well as examinations' 4D-CT MGD scores. Diagnostic performance was assessed. Results: The sample comprised 62 patients (41 women, 21 men; median age 65 years; 47 with SGD, 15 with MGD), with 151 candidate lesions, including 106 high-confidence lesions. Based on second-largest high-confidence lesions, estimated volume at 60-mm³ threshold achieved 53% sensitivity and 96% specificity, while maximum diameter at 7-mm threshold achieved 67% sensitivity and 96% specificity; 4D-CT MGD score ≥3 achieved 47% sensitivity and 68% specificity. For predicting need to remove a gland for successful parathyroidectomy, estimated volume at 114-mm3 threshold achieved 84% sensitivity and 97% specificity, and at 55-mm3 threshold achieved 93% sensitivity and 87% specificity; maximal diameter at 7-mm threshold achieved 93% sensitivity and 84% specificity. Conclusion: Estimated volume and maximum diameter of high-confidence candidate lesions can differentiate SGD from MGD and identify individual glands requiring removal for successful parathyroidectomy. Differentiating SGD and MGD may be aided by considering both first- and second-largest high-confidence lesions. Clinical Impact: The findings will help identify patients likely to require bilateral neck explorations, informing preoperative patient counseling and individualized operative planning.

[Intraoperative measurement of parathyroid hormone in hyperparathyroidism]

Intraoperative parathyroid hormone (IOPTH) determination is based on the short half-life of parathyroid hormone (PTH) and the rapid analytical technology. The IOPTH provides functional information regarding correction of the overproductive state in hyperparathyroidism (HPT) and is superior to macroscopic evaluation of the parathyroid gland (PG) as well as any (intraoperative frozen section) form of histology (so-called biochemical frozen section). In this article the relevance and evaluation of IOPTH is defined for the most important forms of HPT, for primary HPT, renal secondary and tertiary HPT, multiple endocrine neoplasia type 1 (MEN1) and parathyroid carcinoma and clinical scenarios based on the currently available data. It becomes apparent that the additional benefits of IOPTH depend on diverse prerequisites of the specific type of HPT, the diagnostics as well as individual patient factors and strategic considerations for resection. Overall, the costs for IOPTH are comparably low and seem to be justified with respect to the gain in quality. In the hands of specialized endocrine surgeons IOPTH is an essential tool for intraoperative decision-making and quality assurance.

Surgical Management of Normocalcemic Primary Hyperparathyroidism and the Impact of Intraoperative Parathyroid Hormone Testing on Outcome

Objective To review our surgical experience and the impact of intraoperative parathyroid hormone (IOPTH) testing among patients with normocalcemic primary hyperparathyroidism. Study Design Case series with chart review. Setting Academic referral hospital. Subject and Methods Normocalcemic hyperparathyroidism (NCHPT) patients were identified with normal-range blood ionized calcium and serum elevated parathyroid hormone. Patient demographics, intraoperative findings, IOPTH dynamics, and biochemical outcomes were compared with those of classic primary hyperparathyroidism (PHPT) patients. Results Of the 2120 patients who underwent parathyroidectomy, 616 patients met the inclusion criteria: 119 (19.5%) patients had NCHPT, and 497 (80.5%) had classic PHPT. NCHPT patients had higher rates of multigland hyperplasia as compared with classic PHPT (12% vs 4%, P = .002) and smaller gland size ( P < .001). Of 119 NCHPT patients, 114 (97%) achieved >50% drop in IOPTH intraoperatively, as opposed to 492 (99%) among 497 classic PHPT patients ( P = .014). IOPTH drop >50% had an equivalent positive predictive value for long-term cure in both groups. Conclusions Surgeons treating NCHPT patients should suspect the presence of multigland disease and have a low threshold for converting to bilateral exploration depending on IOPTH decay dynamics.

Machine learning to identify multigland disease in primary hyperparathyroidism

BACKGROUND

20%-25% of patients with primary hyperparathyroidism will have multigland disease (MGD). Preoperatative imaging can be inaccurate or unnecessary in MGD. Identification of MGD could direct the need for imaging and inform operative approach. The purpose of this study is to use machine learning (ML) methods to predict MGD.

METHODS

Retrospective review of a prospective database. The ML platform, Waikato Environment for Knowledge Analysis, was used, and we selected models for (1) overall accuracy and (2) preferential identification of MGD. A review of imaging studies was performed on a cohort predicted to have MGD.

RESULTS

2010 patients met inclusion criteria: 1532 patients had single adenoma (SA) (76%) and 478 had MGD (24%). After testing many algorithms, we selected two different models for potential integration as clinical decision-support tools. The best overall accuracy was achieved using a boosted tree classifier, RandomTree: 94.1% accuracy; 94.1% sensitivity, 83.8% specificity, 94.1% positive predictive value, and 0.984 area under the receiver operating characteristics curve. To maximize positive predictive value of MGD prediction, a rule-based classifier, JRip, with cost-sensitive learning was used and achieved 100% positive predictive value for MGD. Imaging reviewed from the cohort of 34 patients predicted to have MGD by the cost-sensitive model revealed 39 total studies performed: 28 sestamibi scans and 11 ultrasounds. Only 8 (29%) sestamibi scans and 4 (36%) ultrasounds were correct.

CONCLUSIONS

ML methods can help distinguish MGD early in the clinical evaluation of primary hyperparathyroidism, guiding further workup and surgical planning.

PRIMARY HYPERPARATHYROIDISM - STRATEGY FOR MULTIGLAND DISEASE IN THE ERA OF SPECT-CT

Purpose

To re-examine our clinical practice and review strategy for treatment of primary hyperparathyroidism in patients with multigland disease.

Methods

Retrospective analysis of 121 consecutive primary hyperparathyroidism (PHPT) patients who underwent surgery in a tertiary center between January 2010 and December 2014.

Results

Of 121 patients with PHPT 87% had single gland adenoma (SGD) and 13% had multigland disease (MGD). The overall cure rate was 95.86%. MGD was more frequent in younger persons (<40y)(50% vs. 13.2%). All patients had SPECT-CT (Single Proton Emission Computerized Tomography) with 28% being SPECT-CT negative. Patients with MGD had a higher rate of persistent disease (13.33% vs. 2.83%). Specimen weight was <600mg in 75% of MGD patients. 67% of SPECT-CT negative patients had mild hypercalcemia (Calcium <2.75 mmol/L) which was more frequent in MGD patients (43% vs. 19%).

Conclusions

MGD patients were more likely SPECT-CT negative (40% vs. 25.4%) and benefit from bilateral neck exploration (BNE) (74%). However, most SPECT-CT negative patients still have a single adenoma. In our series MGD was more frequent in younger patients, more likely SPECT-CT negative, often associated with mild hypercalcemia and had a higher persistence rate than SGD. BNE is the operation of choice in young, SPECT-CT negative patients. If ultrasound parathyroids suggests a single large adenoma, minimally invasive parathyroidectomy with intraoperative PTH monitoring can be considered.