Parathyroid gland anatomical distribution and relation to anthropometric and demographic parameters: a cadaveric study

Incidental parathyroidectomy during total thyroidectomy and functional parathyroid preservation: a retrospective cohort study

BACKGROUND

The published rate of incidental parathyroidectomy (IP) during thyroid surgery varies between 5.8% and 29%. The risk factors and clinical significance of postoperative transient hypocalcemia and permanent hypoparathyroidism are still debated. The aims of this study were to assess the clinical relevance of avoidable IP for transient hypocalcemia and permanent hypoparathyroidism, and to describe the risk factors for IP.

METHODS

This retrospective cohort study included 1,537 patients who had a one-step total thyroidectomy in a high-volume endocrine surgery center between 2018 and 2019. Pathology reports were reviewed for incidentally removed parathyroid glands. Intrathyroidal parathyroid glands were excluded from the study. Demographic characteristics, potential risk factors, and postoperative calcium and PTH levels were compared between IP and control groups.

RESULTS

Avoidable IP occurred in 234 (15.2%) patients. Patients with IP had a higher risk of transient hypocalcemia (17.9% vs. 11.5%, p = 0.006; odds ratio [OR] 1.68, 95% confidence interval [95% CI]1.16-2.45) and permanent hypoparathyroidism (4.7% vs. 1.6%, p = 0.002; OR 3.01, 95% CI 1.29-6.63) than patients without IP. Multivariate analysis showed that central lymph node dissection (CLND) and incidental removal of thymus tissue were independent risk factors for IP (OR 4.83, 95% CI 2.71-8.86, p < 0.001 and OR 1.72, 95% CI 1.02-2.82, p = 0.038).

CONCLUSIONS

Patients with IP were more likely to develop transient hypocalcemia and permanent hypoparathyroidism, indicating the clinical significance of avoidable IP for patients and the need for raising awareness among surgeons. Patients undergoing CLND are at a higher risk for IP, and should be adequately informed and treated. Any removal of thymus tissue should be avoided during CLND.

An improved method of searching inferior parathyroid gland for the patients with papillary thyroid carcinoma based on a retrospective study

Objective

Many surgeons knew the importance of parathyroid gland (PG) in the thyroid surgery, but it was even more difficult to be protected. This study aimed at evaluating the effectiveness of the improved method of searching inferior parathyroid gland (IPG).

Methods

213 patients were enrolled and divided into test and control groups according to different methods of searching IPG in the surgery. Consequently, we compared the surgical outcome parameters between the two groups, including the operative time, numbers of PG identifying (PG protection in situ, PG auto-transplantation, and PG accidental removal), numbers of the total lymph node (LN) and metastatic LN, parathyroid hormone (PTH), transient hypoparathyroidism, transient recurrent laryngeal nerve palsy, and postoperative bleeding.

Results

We identified 194 (194/196, 98.98%) and 215 (215/230, 93.48%) PGs in the test group and control group, respectively, and there was a significant difference (P = 0.005), and this result was due to IPG identification differences (96/98, 97.96% vs. 100/115, 86.96%, P = 0.004). Meanwhile, there was a lower ratio of IPG auto-transplantation in the test group compared with that in the control group (46.94% vs. 64.35%, P = 0.013). Serum PTH one day after the operation was 3.65 ± 1.86 vs. 2.96 ± 1.64 (P = 0.043) but with no difference at 6 months. There were no differences in metastatic LN and recurrent laryngeal nerve palsy between two groups.

Conclusion

The improved method of searching IPG was simple, efficient, and safe, which was easy to be implemented for searching IPG and protecting it well.

Case Report: Primary Hyperparathyroidism due to Posterior Mediastinal Parathyroid Adenoma With One-Year Follow-Up

Ectopic parathyroid adenoma, though rare, is one of the causes of persistent hyperparathyroidism and recurrence of hyperparathyroidism. Ectopic parathyroid glands can be seen in thymus, thyroid, and mediastinum. However, ectopic parathyroid adenoma occurred in the posterior superior mediastinum is extremely rare. Here, we report a case of primary hyperparathyroidism caused by ectopic parathyroid adenoma located in the posterior superior mediastinum. Serum parathyroid hormone, calcium, and vitamin D levels of the patient was followed up for one year.

Clinical Relevance and Management of Recurrent Laryngeal Nerve Inlet Zone Lymph Nodes Metastasis in Papillary Thyroid Cancer

BACKGROUND

Recurrent nodal disease often occurs in recurrent laryngeal nerve inlet zone (RLNIZ), leading to difficult surgical management.

METHODS

Medical records of 947 patients with PTC and 33 patients with recurrent PTC were retrospectively reviewed. Totally 169 sides of RLNIZ dissection in 152 patients (17 cases were bilateral and 135 cases were unilateral) with primary surgery and 4 patients with structural recurrent disease were included for the analysis.

RESULTS

The rate of lymph node metastasis in RLNIZ was 31.3% (47/150). The incidence of transient hypoparathyroidism was 5.9% and no RLN injury and permanent hypoparathyroidism occurred. RLNIZ lymph nodes metastasis (LNM) was significantly associated with age <45 years, larger tumor size, number of CNLNM, and lateral node metastasis. CNLNM and lateral node metastasis were independent risk factors for RLNIZ LNM. Recurrent nodal disease in RLNIZ was identified in four of 33 patients and permanent recurrent laryngeal nerve (RLN) injury was observed in one of four patients.

CONCLUSION

Lymph nodes in RLNIZ are usually involved in patients with heavy tumor burden and can be removed safely at initial surgery. Once central or lateral LNM was confirmed preoperatively or intraoperatively, RLNIZ lymph node dissection should be carefully performed to reduce the rate of structural recurrence in the central compartment.

Surgical strategy when identifying less than four parathyroid glands during total thyroidectomy: a retrospective cohort study

Background

Parathyroid glands protection is still controversial in patients with less than 4 parathyroid glands during thyroidectomy. The aim of this study was to investigate the strategy of parathyroid autotransplantation or in situ preservation in patients with 3 parathyroid glands.

Methods

Consecutive patients who underwent primary total thyroidectomy with bilateral central neck dissection for papillary thyroid carcinoma (PTC) in our center were included retrospectively. Serum calcium and parathyroid hormone (PTH) levels (pg/mL), incidence of hypocalcemia and hypoparathyroidism during 24 months follow-up were compared grouping by the number of parathyroid glands both identified intraoperatively and confirmed postoperatively by pathology.

Results

A total of 1,424 patients were included. Serum PTH and calcium levels were lower and the incidence of hypocalcemia was higher in patients with 3 identified parathyroid glands. When excluding patients with accidental parathyroid resection, the results remained similar. Of the 212 patients with 3 identified parathyroid glands, PTH levels at postoperative 12-month in patients underwent autotransplantation were significantly lower than patients with all parathyroid glands preserved in situ (3.65±1.30 vs. 4.67±1.89, P=0.026).

Conclusions

The parathyroid function was weaker in patients with 3 parathyroid glands than patients with 4 before and after operation. Parathyroid glands preserved all in situ promoted better recovery of postoperative function in patients with 3 identified parathyroid glands.

99mTc-MIBI SPECT/CT imaging had high sensitivity in accurate localization of parathyroids before parathyroidectomy for patients with secondary hyperparathyroidism

Purpose: Accurate preoperative parathyroid localization is important for successful parathyroidectomy (PTX). The aim of our study was to investigate whether SPECT/CT has enhanced effect in preoperative localization of parathyroids. Methods: In our retrospective cohort study, we evaluated the effects of technetium-99m methoxyisobutylisonitrile-single-photon emission computed tomography/computed tomography (^99mTc-MIBI SPECT/CT) on preoperative parathyroid localization for 645 secondary hyperparathyroidism (SHPT) patients. Among them, 569 successful PTX patients were divided into group A (received ^99mTc-MIBI scintigraphy, n = 175) and group B (received ^99mTc-MIBI scintigraphy and SPECT/CT imaging, n = 394). Sensitivity, specificity, and consistency of two imaging methods in preoperative localization of parathyroids were compared. Results: Overall sensitivity and consistency were higher in group B, while there was no difference in specificity between the two groups. In group A, the sensitivity of ^99mTc-MIBI was 50.00%, 77.11%, 61.76%, and 76.54% in the right upper gland (RU), right lower gland (RL), left upper gland (LU), and left lower gland (LL) subgroups, while the consistency was 52.00%, 76.57%, 61.71%, and 75.43%, respectively. In group B, the sensitivity of ^99mTc-MIBI with SPECT/CT was 69.39%, 90.03%, 78.07%, and 84.27%, and the consistency was 69.54%, 88.32%, 78.43%, and 84.26%, respectively. The sensitivity and consistency in lower glands were higher than in upper glands in both groups. Sensitivity for eutopic parathyroid was higher in group B, while there was no difference for ectopic parathyroid. Conclusions: ^99mTc-MIBI SPECT/CT can increase the sensitivity and consistency of preoperative localization of eutopic parathyroid glands, and it can accurately locate ectopic parathyroid without sensitivity improvement.

[Ectopic tissue of the thyroid gland and the parathyroid glands]

Ectopic thyroid tissue results from developmental defects of the early stages of thyroid embryogenesis, in which the median thyroid anlage descends from the floor of the mouth to its final pre-tracheal position. The most common sites of ectopic thyroid tissue are accordingly in the area of the floor of the mouth and in the course of the thyroglossal duct. Rare localizations are intrathoracic (mediastinal, cardiac, pulmonary) and sub-diaphragmatic (including the adrenals, liver, gall bladder, and gastrointestinal tract). The most important differential diagnosis of ectopic thyroid is metastasis of differentiated thyroid carcinoma.By contrast, the term parathyroidectopy is not uniformly defined. Usually, the cervical-central localizations are referred to as "positional variants" (with the exception of the maxillary sinus and high parapharyngeal), whereas the cervical-lateral localizations (carotid sheath, vagus nerve) and those below the brachiocephalic and mediastinal positions (extraligamentary, aortopulmonary window, paravagal) and other rare localizations are classified as "ectopic parathyroid tissue". Parathyroidectomy is very common (in autopsy studies in 28 to 42.8% of all humans). In the context of primary hyperparathyroidism (pHPT), there is a prevalence of 6.3 to 16% of ectopic hyperfunctional parathyroid tissue (predominantly adenomas), which play an important role in the surgical treatment of pHPT.

The prevalence and anatomy of parathyroid glands: a meta-analysis with implications for parathyroid surgery

Purpose

The anatomy of parathyroid glands (PTG) is highly variable in the population. The aim of this study was to conduct a systematic analysis on the prevalence and location of PTG in healthy and hyperparathyroidism (HPT) patients.

Methods

An extensive search of the major electronic databases was conducted to identify all studies that reported relevant data on the number of PTG per patient and location of PTG. The data was extracted from the eligible studies and pooled into a meta-analysis.

Results

The overall analysis of 26 studies (n = 7005 patients; n = 23,519 PTG) on the number of PTG showed that 81.4% (95% CI 65.4–85.8) of patients have four PTG. A total of 15.9% of PTG are present in ectopic locations, with 11.6% (95% CI 5.1–19.1) in the neck and 4.3% (95% CI 0.7–9.9) in mediastinum. The subgroup analysis of ectopic PTG showed that 51.7% of ectopic PTG in the neck are localized in retroesophageal/paraesophageal space or in the thyroid gland. No significant differences were observed between the healthy and HPT patients and cadaveric and intraoperative studies.

Conclusions

Knowledge regarding the prevalence, location, and anatomy of PTG is essential for surgeons planning for and carrying out parathyroidectomies, as any unidentified PTG, either supernumerary or in ectopic location, can result in unsuccessful treatment and need for reoperation.

Electronic supplementary material

The online version of this article (10.1007/s00423-019-01751-8) contains supplementary material, which is available to authorized users.

Clinicopathological characteristics of incidental parathyroidectomy after total thyroidectomy: The effect on hypocalcemia. A retrospective cohort study

BACKGROUND

The reported rate of incidental parathyroidectomy (IP) during total thyroidectomy varies between 6.4 and 31.1%. The aim of this study was to investigate the clinicopathological characteristics associated with IP.

MATERIALS AND METHODS

This is a retrospective cohort study which included 2556 patients who underwent total thyroidectomy between 2002 and 2012 at a single tertiary institution. Demographics, clinicopathological risk factors, and postoperative calcium levels were compared between IP and control group.

RESULTS

Incidental parathyroidectomy occurred in 18.3% of patients. IP patients had higher risk of postoperative biochemical (40.3% vs 17.3%, p < 0.001) and symptomatic hypocalcemia (14.3% vs 7.3%, p < 0.001) than no-IP group. Multivariate analysis showed malignancy, tumor size >10 mm, thyroid capsule invasion, extrathyroidal extension, lymph node metastases and central neck dissection, operation time, RLN injury, thyroid gland dimensions were independent risk factors for IP.

CONCLUSIONS

Our results indicate that patients with certain preoperative findings such as larger thyroid dimensions, diagnosis of malignancy and especially tumor >10 mm, extrathyroidal extension, and lymph node metastasis are at higher risk of IP and postoperative symptomatic hypocalcemia and these patients should be adequately informed and treated. Α meticulous intraoperative identification and the preservation of all parathyroid glands results in lower incidence of IP and postoperative hypocalcemia.

Diagnosis and treatment of hypoparathyroidism: a position statement from the Brazilian Society of Endocrinology and Metabolism

Objective To present an update on the diagnosis and treatment of hypoparathyroidism based on the most recent scientific evidence. Materials and methods The Department of Bone and Mineral Metabolism of the Sociedade Brasileira de Endocrinologia e Metabologia (SBEM; Brazilian Society of Endocrinology and Metabolism) was invited to prepare a document following the rules set by the Guidelines Program of the Associação Médica Brasileira (AMB; Brazilian Medical Association). Relevant papers were retrieved from the databases MEDLINE/PubMed, LILACS, and SciELO, and the evidence derived from each article was classified into recommendation levels according to scientific strength and study type. Conclusion An update on the recent scientific literature addressing hypoparathyroidism is presented to serve as a basis for the diagnosis and treatment of this condition in Brazil.

Use of prophylactic oral calcium after total thyroidectomy: a prospective study

OBJECTIVE

The aim of this study was to evaluate the use of prophylactic oral calcium after total thyroidectomy in the prevention of symptomatic hypocalcemia, and to develop a rational strategy of oral calcium supplementation following this type of surgery.

SUBJECTS AND METHODS

Prospective study including 47 patients undergoing total thyroidectomy from January 2007 to February 2012. The patients were allocated to one of the following groups: I (no postoperative calcium) or II (oral calcium 3 g per day). Oral calcium was started at the first postoperative day and administered until the sixth postoperative day. The patients were followed up for a minimum of 6 months and evaluated with a minimum of five measurements of ionized calcium: preoperative, 16 hours after surgery, seventh postoperative day, and at postoperative days 90 (PO90) and 180 (PO180). The cohort included three men and 44 women, of whom 24 (51.9%) had benign thyroid disease, and 23 had suspected or confirmed malignant disease.

RESULTS

When compared with Group II, Group I had significantly higher rates of postoperative biochemical hypocalcemia at PO1 and PO180, and of symptomatic hypocalcemia at PO1, PO7, and PO90. Other data were not significantly different between the groups.

CONCLUSION

We conclude that postoperative calcium supplementation effectively prevents symptomatic and biochemical hypocalcemia after total thyroidectomy, and can be safely used after this procedure. The presented strategy of oral calcium supplementation may be implemented in a viable manner.

Cytomorphologic features distinguishing Bethesda category IV thyroid lesions from parathyroid

Background:

Thyroid follicular cells share similar cytomorphological features with parathyroid. Without a clinical suspicion, the distinction between a thyroid neoplasm and an intrathyroidal parathyroid can be challenging. The aim of this study was to assess the distinguishing cytomorphological features of parathyroid (including intrathyroidal) and Bethesda category IV (Beth-IV) thyroid follicular lesions, which carry a 15%–30% risk of malignancy and are often followed up with surgical resection.

Methods:

A search was performed to identify “parathyroid” diagnoses in parathyroid/thyroid-designated fine-needle aspirations (FNAs) and Beth-IV thyroid FNAs (follicular and Hurthle cell), all with diagnostic confirmation through surgical pathology, immunocytochemical stains, Afirma^® analysis, and/or clinical correlation. Unique cytomorphologic features were scored (0-3) or noted as present versus absent. Statistical analysis was performed using R 3.3.1 software.

Results:

We identified five FNA cases with clinical suspicion of parathyroid neoplasm, hyperthyroidism, or thyroid lesion that had an eventual final diagnosis of the parathyroid lesion (all female; age 20–69 years) and 12 Beth-IV diagnoses (11 female, 1 male; age 13–64 years). The following cytomorphologic features are useful distinguishing features (P value): overall pattern (0.001), single cells (0.001), cell size compared to red blood cell (0.01), nuclear irregularity (0.001), presence of nucleoli (0.001), nuclear-to-cytoplasmic ratio (0.007), and nuclear chromatin quality (0.028).

Conclusions:

There are cytomorphologic features that distinguish Beth-IV thyroid lesions and (intrathyroidal) parathyroid. These features can aid in rendering correct diagnoses and appropriate management.

Intra-operative parathyroid hormone monitoring through central laboratory is accurate in renal secondary hyperparathyroidism

OBJECTIVE

The usefulness, the methods and the criteria of intra-operative monitoring of the parathyroid hormone (ioPTH) during parathyroidectomy (PTX) for renal secondary hyperparathyroidism (rSHPT) in patients on chronic hemodialysis remain still matter of debate. The present study aimed to evaluate the ability of a low cost central-laboratory second generation PTH assay to predict an incomplete resection of parathyroid glands (PTG).

METHODS

The ioPTH decay was determined In 42 consecutive patients undergoing PTX (15 subtotal and 27 total without auto-transplant of PTG) for rSHPT. The ioPTH monitoring included five samples: pre-intubation, post-manipulation of PTG and at 10, 20 and 30min post-PTG excision. The patients with PTH exceeding the normal value (65pg/ml) at the first postoperative week, 6 and 12months were classified as persistent rSHPT.

RESULTS

The concentrations of ioPTH declined significantly over time in patients who received total or subtotal PTX; however, no difference was found between the two types of PTX. Irrespective of the type of PTX and the number of PTG removed, combining the absolute and percentage of ioPTH decay at 30min after PTG excision, we found high sensitivity (100%), specificity (92%), negative predictive value (100%) and accuracy (93%) in predicting the persistence of rSHPT.

CONCLUSIONS

The monitoring of the ioPTH decline by a low cost central-laboratory second generation assay is extremely accurate in predicting the persistence of disease in patients on maintenance hemodialysis undergoing surgery for rSHPT.

Value of Prophylactic Cervical Thymectomy in Parathyroid Hyperplasia

BACKGROUND

In parathyroid hyperplasia (HPT), parathyroid glands within the cervical thymus are a cause for recurrence. As a result of differences in pathophysiology, variable practice patterns exist regarding performing bilateral cervical thymectomy (BCT) in primary hyperplasia versus hyperplasia from renal failure or familial disease. The objective of this study was to capture patients where thymic tissue was found with subtotal parathyroidectomy (PTX) and intended BCT, identify number of thymic supernumerary glands (SNGs), and determine overall cure rate.

METHODS

Retrospective review of patients with four-gland exploration and intended BCT for HPT from 2000 to 2013 was performed. Identification of thymic tissue and SNGs were determined by operative/pathology reports. Univariate analysis identified differences in cure rate for patients undergoing subtotal PTX with or without BCT.

RESULTS

Thymic tissue was found in 52 % of 328 primary HPT (19 % unilateral, 33 % bilateral), 77 % of 128 renal HPT (28 % unilateral, 49 % bilateral), and 100 % of familial HPT (24 % unilateral, 76 % bilateral) patients. Nine percent of primary, 18 % of renal, and 10 % of familial HPT patients had SNGs within thymectomy specimens. Cure rates of primary HPT patients with BCT were 99 % compared to 94 % in subtotal PTX alone. Renal HPT cure rates were 94 % with BCT compared to 89 % without BCT.

CONCLUSIONS

Renal HPT patients benefited most in cure when thymectomy was performed. Although the rate of SNGs found in primary HPT was lower than renal HPT, the cure rate mimicked the pattern in renal disease. Furthermore, the incidences of SNGs in primary and familial HPT were similar. On the basis of these data, we advocate that BCT be considered in primary HPT when thymic tissue is readily identified.

Identification of parathyroid glands: anatomical study and surgical implications

While performing thyroid surgery, the unintentional lesion of parathyroid glands and laryngeal nerves results in a profound alteration in patient's quality of life. To minimize thyroid surgery morbidity, the surgeon must have an in-depth knowledge of the thyroid gland morphology and its anatomical relations in the anterior compartment of the neck. This work intended to simulate total thyroidectomies using cadaver parts and isolate fragments that may correspond to parathyroid glands. The thyroid glands and "eventual" parathyroid glands were then submitted to histological study. Ninety-two cadaver parts were used for macroscopic dissection. A total of 242 fragments were isolated, 154 of which were confirmed through histological study to be parathyroid glands. In 36 cases, all "eventual" parathyroid glands isolated during dissection were confirmed through histological verification. In 40 cases, some glands were confirmed. In 16 cases, none of the "eventual" parathyroid glands was confirmed. The 92 thyroid glands isolated during dissection were also submitted to histological study. In 21 thyroid glands, 16 parathyroid glands were identified in the histological cuts: 8 sub-capsular, 8 extra-capsular, 6 intra-thyroidal. There was no statistical difference between the dimensions of the parathyroid glands. Parathyroid gland identification and preservation are sometimes a challenge during thyroid surgery, difficulty that has been demonstrated during dissection of cadaver parts.