The anatomical basis for preserving the blood supply to the parathyroids during thyroid surgery, and a review of current technologic advances.

BACKGROUND: Devascularization of the parathyroid glands is generally accepted as the most common mechanism for iatrogenic hypocalcemia, a frequently seen complication of both total and completion thyroidectomy procedures. Much has been written about iatrogenic hypoparathyroidism, but few papers have precisely delineated the arterial supply of the parathyroid glands and the common anatomical variations that may impact parathyroid preservation during thyroid surgery. METHODS: We offer an illustrated review and discussion of the only two anatomic studies published in the medical literature focusing on parathyroid vasculature. In addition, we examine current techniques of parathyroid identification, preservation, and classification. FINDINGS: A surgical technique that preserves the parathyroid arteries is vital to preserving the viability of the parathyroid gland(s) during thyroid surgery. In 1907, Halsted and Evans described a technique of ligating the distal branches of the thyroid arteries beyond the origin of the parathyroid arteries, a technique termed ultra-ligation. In 1982, Flament et al.. reported three distinct anatomical variations of the parathyroid arteries which place the parathyroid blood supply at risk for devascularization during thyroid surgery. Our review also highlights novel techniques that aid surgeons in identification and assessment of the parathyroid glands. CONCLUSIONS: Recognition of the variations of parathyroid anatomy and their potential to lead to devascularization aids thyroid surgeons in their pursuit of parathyroid preservation. An awareness of the variety of novel parathyroid identification and preservation techniques can assist surgeons to achieve this goal.

Comparing intraoperative parathyroid identification based on surgeon experience versus near infrared autofluorescence detection - A surgeon-blinded multi-centric study.

BACKGROUND: Near infrared autofluorescence (NIRAF) detection has previously demonstrated significant potential for real-time parathyroid gland identification. However, the performance of a NIRAF detection device - PTeye® - remains to be evaluated relative to a surgeon's own ability to identify parathyroid glands. METHODS: Patients eligible for thyroidectomy and/or parathyroidectomy were enrolled under 6 endocrine surgeons at 3 high-volume institutions. Participating surgeons were categorized based on years of experience. All surgeons were blinded to output of PTeye® when identifying tissues. The surgeon's performance for parathyroid discrimination was then compared with PTeye®. Histology served as gold standard for excised specimens, while expert surgeon's opinion was used to validate in-situ tissues. RESULTS: PTeye® achieved 92.7% accuracy across 167 patients recruited. Junior surgeons (<5 years of experience) were found to have lower confidence in parathyroid identification and higher tissue misclassification rate per specimen when compared to PTeye® and senior surgeons (>10 years of experience). CONCLUSIONS: NIRAF detection with PTeye® can be a valuable intraoperative adjunct technology to aid in parathyroid identification for surgeons.

Location and Vascular Classification of 188 parathyroid glands in New Zealand White Rabbits / [Localização e Classificação Vascular de 188 glândulas paratireoidianas em coelhos brancos da Nova Zelândia]

The function and protection of the parathyroid glands are increasingly popular research topics. New Zealand white rabbits are the most commonly used animal model of parathyroid ischemia. However, information on the vasculature of their parathyroid glands is limited. We used 94 healthy New Zealand white rabbits, 3-4 months of age and 2-3kg in weight, for exploration of the parathyroid glands, which were stained using hematoxylin and eosin (HE) after removal. The following types were classified according to the relationship between the position of the inferior parathyroid gland and the thyroid: Type A, Close Type, Type B, and Distant Type. There were 188 cases, 4 where the inferior parathyroid glands were located near the dorsal side of thyroid (2.13%), 8 where the inferior parathyroid glands were located superior to the upper pole of the thyroid (4.26%), 20 where the inferior parathyroid glands were located parallel to the thyroid (10.64%), and 155 cases where the inferior parathyroid glands were located inferior to the lower pole of thyroid (82.45%). Identifying the location and classifying the vasculature of the parathyroid glands in New Zealand white rabbits will provide an anatomical model to assist in future research.(AU)

A função e proteção das glândulas paratireoidianas é um tópico de pesquisa cada vez mais popular. Coelhos brancos da Nova Zelândia são o modelo animal mais comumente usada para isquemia da paratireóide. Porém, informação sobre a vasculatura de suas glândulas paratireóides é limitada. Foram usados 94 coelhos brancos da Nova Zelândia saudáveis, com 3-4 meses de idade, 2-3kg de peso, para exploração das glândulas paratireóides, que foram coradas com hematoxilina e eosina (HE) após a remoção. Os seguintes tipos foram classificados de acordo com a relação entre a posição da glândula paratireoidiana inferior e a tireoide: Tipo A, Tipo Próximo, Tipo B e Tipo Distante. Houve 188 casos, 4 em que as glândulas paratireoidianas inferiores estavam localizadas próximas ao lado dorsal da tireoide (2.13%), 8 onde as glândulas paratireoidianas inferiores estavam localizadas superiores ao polo superior da tireoide (4.26%), 20 onde as glândulas paratireoidianas inferiores estavam localizadas paralelo à tireoide (10.64%) e 155 casos em que as glândulas paratireoidianas inferiores estavam localizadas inferiores ao polo inferior da tireoide (82.45%). A identificação da localização e a classificação da vasculatura das glândulas paratireóides em coelhos brancos da Nova Zelândia fornecerão um modelo anatômico para auxiliar em pesquisas futuras.(AU)

Evaluación endocrinológica del paciente con enfermedad nodular tiroidea / Endocrinologic approach to the patient with thyroid nodules

Llamamos nódulo tiroideo a aquella lesión concreta palpable o radiológicamente distinguible del parénquima tiroideo. La enfermedad nodular tiroidea tiene una prevalencia progresivamente creciente a medida que ha mejorado la calidad de las técnicas de imagen, principalmente la ecografía. El objetivo de la presente revisión es señalar cuales son los pasos en la evaluación endocrinológica del paciente con enfermedad nodular tiroidea. Más concretamente, cual es la mejor estrategia coste/efectiva para diagnosticar los nódulos tiroideos malignos. Tras una buena anamnesis y exploración clínica, el estudio se completa con una determinación de TSH y la realización de una ecografía tiroidea, que es la prueba diagnóstica que más criterios aporta para poder hacer la indicación de PAAF. La muestra obtenida se estudiará según el sistema Bethesda

Thyroid nodule is defined as a palpable lesion o radiologically distinguishable from thyroid parenchyma. Its prevalence is increasing with the improvement of the imagine techniques, mainly the ultrasonography. The aim of this review is to indicate the steps for the endocrinology evaluation of the patient with thyroid nodules, particularly to choose the best cost/effective strategy to diagnose the malignant thyroid nodules. After having the anamnesis and physical examination done, a TSH determination and an thyroid ultrasound are needed. The sample obtained will be studied according to the Bethesda system

The inferior parathyroid glands preserved in site recover faster than the superior parathyroid glands preserved in site after thyroid surgery for carcinoma.

Due to the great difficulty in being preserved in site for the variable positions, the inferior parathyroid glands were advised to being routinely autotransplanted to prevent permanent hypoparathyroidism. The aim of this study was to compare the performance in the function of the superior parathyroid glands preserved in site with that of the inferior parathyroid glands preserved in site.We conducted a retrospective study including patients who underwent thyroid surgery for papillary thyroid carcinoma at our department between January 2014 and June 2018. According to the number and original position of the autoplastic parathyroid gland(s), patients were divided into group 1 (1 superior parathyroid gland), group 2 (1 inferior parathyroid glands), group 3 (1 superior parathyroid gland and 1 inferior parathyroid gland) and group 4 (2 inferior parathyroid glands). The postoperative complications and serum parathyroid hormone and calcium were analyzed.A total of 368 patients were included in the study, among them 27, 243, 40, and 58 patients were divided into group 1, group 2, group 3, and group 4, respectively. Compared with those in group 2, the serum parathyroid hormones were higher at 1 week (2.98 ±â€Š1.52 vs 2.42 ±â€Š0.89, P = .049) and 2 weeks (3.49 ±â€Š1.42 vs 2.8 ±â€Š0.81, P = .019) postoperatively in group 1. There was also significantly different in the serum parathyroid hormone at 2 weeks postoperatively between group 3 and group 4 (2.95 ±â€Š0.98 vs 2.58 ±â€Š0.82, P = .047).The inferior parathyroid glands preserved in site recover faster than the superior parathyroid glands preserved in site.

A simple, efficient, and safe way of finding recurrent laryngeal nerve beneficial for PTC patients.

BACKGROUND: More surgeons have known the importance of parathyroid grand and recurrent laryngeal nerve protection in the surgery, but there is still plenty of scope to improve the surgical techniques. This study aims at investigating whether the improved method of finding recurrent laryngeal nerve (RLN) can protect parathyroid grand and RLN. METHODS: One hundred fifty-eight patients were enrolled and divided randomly into the test and control group according to different methods of finding RLN in the surgery. In the experimental group the author could quickly find the laryngeal recurrent nerve in the lower part of the neck and separate along the surface of the recurrent laryngeal nerve to the point where the recurrent laryngeal nerve gets into the larynx close to the thyroid gland named lateral approach, while in the control group the author severed the middle and lower thyroid vein and raised the lower thyroid pole to look for the RLN near the trachea by the blunt separation. RESULTS: The author identified 152 and 159 parathyroid glands in the test and control group, respectively and there were a lower ratio of auto-transplantation and less operative time in the test group compared with that in the control group. The author also found that the parathyroid hormone level (1 day and 2 months) in the test group was higher than that in the control group. There were no differences in metastatic LN and recurrent laryngeal nerve palsy in the 2 groups. CONCLUSION: The improved method of finding RLN is a simple, efficient and safe way, and easy to implement.

Application of carbon nanoparticles in localization of parathyroid glands during total parathyroidectomy for secondary hyperparathyroidism.

BACKGROUND: Intraoperative imaging is used to address the challenges of parathyroidectomy, but no standard modality has been established. This study aimed to assess whether carbon nanoparticle injection is useful in localizing parathyroid glands (PGs) during parathyroidectomy. METHODS: Patients who underwent total parathyroidectomy (TPTX) between September 2015 and November 2018 were included. The operative duration and intact parathyroid hormones (iPTH) were analyzed. RESULTS: A total of 61 patients were included; of these, 32 with carbon nanoparticle injection (TPTX + CN group) and 29 without (TPTX group). The operative duration in the TPTX + CN group was significantly shorter (90.6 ± 21.2 vs 101.4 ± 19.4 min, P = 0.042), which is more apparent in those with normal sized PGs. For those with four enlarged PGs, iPTH levels on 1 day and 1 year postoperatively were significantly lower in the TPTX + CN group (P = 0.032 and P = 0.036, respectively). CONCLUSION: Carbon nanoparticles are useful in the identification normal sized PGs and complete resection of enlarged PGs.

Surgical options in treating patients with primary hyperparathyroidism.

Background Primary hyperparathyroidism is the third most common endocrine disorder for which surgical procedure called parathyroidectomy is the most effective treatment. Since the early 20th century, parathyroid surgery has improved extensively. With the advances in preoperative imaging and with understanding the causes of disease, new and minimally invasive surgical approaches overrode the standard bilateral exploratory operations. Directed parathyroidectomy is currently the standard technique for treatment of primary hyperparathyroidism worldwide. Conclusions Surgery is the only definitive treatment of primary hyperparathyroidism. The most appropriate type of surgical procedure depends on the number and localization of the hyperactive parathyroid glands, availability of modern imaging techniques, limitation of each type of procedure and expertise.

Parathyroidectomy Without the Utilisation of iPTH: The Gold Standard is Still a Good Operation-How Understanding the Anatomy and a Simple US Can Help.

Parathyroid surgery is frequently performed after at least two preoperative localisation studies, in addition to the use of intraoperative ioPTH. The key to performing a successful parathyroidectomy is reliant on the surgeon having an outstanding knowledge of parathyroid embryology and anatomy. With this, it is possible to undertake surgery with a simple neck ultrasound and without more expensive pre- and intraoperative localisation studies.

Anatomía quirúrgica de las glándulas tiroides y paratiroides / Surgycal anatomy of the thyroid and parathyroid glands

Nuestro objetivo es lograr un relato de los detalles anatómicos que ayude al cirujano a conseguir intervenciones seguras, se elude el estilo de las anatomías descriptivas o topográficas tratando de producir una anatomía verdaderamente quirúrgica. Para ello se mencionan las fascias, estructuras capsulares y ligamentos que envuelven a la tiroides. Se hace hincapié en la vascularización, principalmente en lo referente a la arteria tiroidea inferior, fundamental para la localización del nervio recurrente. También en lo relacionado con el conjunto del drenaje venoso, que con su complicada distribución dificulta notablemente la disección. Relatamos minuciosamente las variantes anatómicas y las anomalías que afectan a la estructura de la región, su conocimiento es fundamental ante la posibilidad de que el cirujano encuentre en sus operaciones alguna de ellas. Describimos el aspecto, las relaciones y lo referente a la localización de las glándulas paratiroides, detalles necesarios para evitar su resección inopinada en las tiroidectomías y para el reconocimiento de la glándula patológica en el hiperparatiroidismo

The aim of this article is describe the anatomical details that helps the surgeon to achieve safe surgeries, the style of descriptive or topographic anatomies is avoided trying to produce a truly surgical anatomy. For this, fascias, capsular structures and ligaments that surround the thyroid gland are mentioned. Emphasis is placed on vascularization, mainly in relation to the inferior thyroid artery, essential for the location of the recurrent nerve. Also in relation to the whole of the venous drainage, which with its complicated distribution makes dissection remarkably difficult. We carefully describe the anatomical variants and the anomalies that affect the structures of the region, their knowledge is fundamental to the possibility that the surgeons finds in their surgeries. We describe the appearance, the relationships and the reference to the location of the parathyroid glans. Neccesary details to avoid their inopinate resection in thyroidectomies and for the recognition of the pathological gland in the hyperparathyroidism

Parathyroid Pathology.

Proliferative pathologic lesions of parathyroid glands encompass a spectrum of entities ranging from benign hyperplastic processes to malignant neoplasia. This review article outlines the pathophysiologic classification of parathyroid disorders and describes histologic, immunohistochemical, and molecular features that can be assessed to render accurate diagnoses.

Fast and reliable dissection of porcine parathyroid glands - A protocol for molecular and histological analyses.

As calcium and phosphorus are of vital importance for life, physiological activity of the parathyroid glands (PTGs) is crucial to maintain mineral homeostasis and bone mineralization. However, PTG-specific molecular routes in response to environmental factors and intrinsic hormonal responses are not yet fully understood. Since nutrient requirements, pathophysiology and functional genomics of pigs are similar to those of humans, pigs might be a suitable model to study the holistic gene expression and physiological aspects of the parathyroid gland, which could be used in both animal sciences and biomedical research. However, due to their small size and hidden location, the dissection of the PTGs, particularly in pigs, is difficult. Therefore, a protocol for untrained dissectors has been established that allows a fast and reliable identification of the PTGs in domestic pigs. Based on their localization within the cranial thymus near the carotid bifurcation, sampling was verified by histological staining and mRNA expression pattern. Analyses revealed the prominence of parathyroid hormone (PTH)-producing chief cells. Moreover, the copy numbers of PTH differed substantially between the PTGs and their surrounding thymus tissue, as PTH was expressed virtually exclusively in the PTGs. The developed protocol will substantially facilitate a fast and reliable dissection of porcine PTGs which is essential for studies characterizing the molecular mechanisms of parathyroid glands, e.g. when applying new feeding strategies in pigs.

Cotton rats (Sigmodon hispidus) possess pharyngeal pouch remnants originating from different primordia.

Pharyngeal pouches in mammals develop into specific derivatives. If the differentiation of the pharyngeal pouches is anomalous, their remnants can result in cysts, sinuses, and fistulae in the differentiated organs or around the neck. In the present study, we found several pharyngeal pouch remnants, such as cystic structures in thymus and parathyroid gland and fossulae extended from the piriform fossa, in the inbred cotton rats maintained at Hokkaido Institute of Public Health (HIS/Hiph) and University of Miyazaki (HIS/Mz). In HIS/Hiph, the fossulae extended from the apex of the piriform fossa into the thyroid glands and were lined with stratified squamous and cuboidal epithelium. Calcitonin-positive C-cells were present within their epithelium in HIS/Hiph. In contrast, the fossulae of HIS/Mz ran outside the thyroid glands toward the parathyroid glands; they were lined with columnar ciliated epithelium and a few goblet cells, but had no C-cells, which was consistent with the cystic structures in the thymus and the parathyroid gland. These results indicated that the fossulae were a remnant of the ultimobranchial body in HIS/Hiph and of the thymopharyngeal duct in HIS/Mz. Thus, the fossulae of the piriform fossa resembled the piriform sinus fistula in human. In conclusion, cotton rats frequently possessed pharyngeal pouch remnants, including the piriform sinus fistula, and therefore, might serve as a novel model to elucidate the mechanisms of pharyngeal pouch development.

Retropharyngeal Parathyroid Glands: Important Differences.

INTRODUCTION: In primary hyperparathyroidism (PHPT), parathyroid ectopia is seen in up to 22% leading to more difficult surgery. We aimed to determine the rate and characteristics of retropharyngeal (RP) parathyroid glands. METHODS: A prospective database was queried for patients with sporadic PHPT who had surgery from 1997 to 2016. The data of RP patients were compared to those who had surgery for sporadic PHPT over the same time period with hyperfunctioning parathyroids in anatomically normal positions (N). RESULTS: RP glands occurred in 47/3006 (1.6%) patients and were more common at reoperative than initial surgery (5.5 vs 1.4%, p < 0.01). RP patients had prior failed surgery more often than N patients (17 vs 3.1%, p < 0.01). Preoperative calcium levels (p = 0.06), PTH levels (p = 0.15), and mean gland weights (p = 0.07) were similar among groups. For RP glands, ultrasound imaging was negative in all but one patient, while 99mTc-sestamibi accurately indicated a posterior midline position in only 13/47 (28%) and was negative in 21%. All RP glands were anatomically superior. RP patients more often required > 1 post-resection intraoperative PTH level (36 vs 21%, p = 0.02). Failure due to persistent PHPT was more likely in RP patients (4.7 vs 2.1%, p = 0.2). CONCLUSION: In PHPT, hyperfunctioning RP glands are seen in 1.6% of cases and often associated with initial failure (17%). At reoperation, RP ectopia is 4X more common. RP glands are associated with a high rate of negative imaging, but imaging results suggestive of a midline abnormality can guide exploration. The RP space should be evaluated prior to ending an otherwise unfruitful surgery.

Parathyroid, Thyroid and Recurrent Laryngeal Nerve Anatomy in an Indian Rhinoceros (Rhinoceros unicornis).

INTRODUCTION: The parathyroid gland was first identified in the Indian rhinoceros in 1849 by Sir Richard Owen. We performed a necropsy in an Indian rhinoceros, recapitulating Owen's dissection and display what appear to be the initial identification of the recurrent laryngeal nerve in situ and the anatomy and histology of the largest rhinoceros parathyroid glands yet identified. MATERIALS AND METHODS: Patrick T. Rhino, a 41-year-old Indian rhinoceros was born in 1974. His early years were unremarkable. In 2006, he was donated to White Oak Conservation in Yulee, Florida, where he bred and sustained minor injuries. In his geriatric years, he developed a cataract and degenerative joint disease (DJD). At age 41, he developed progressive ataxia and lameness and was euthanized to minimize suffering when he was unable to stand. ROS, FH, SH and medication history were unremarkable. Physical exam was age and species appropriate. Pre-mortem serum demonstrated: creat 1.8 mg/dL (0.8-2.1), calcium 10.6 mg/dL (9.7-13.1), phos 3.8 mg/dL (2.5-6.7), alk phos 69 U/L (26-158) and intact PTH 44.1 pg/mL (rhinoceros reference range: unknown). Necropsy revealed intervertebral DJD with thoracic spondylosis, which combined with osteoporosis, resulted in thoracic myelopathy and ataxia. The neck block was sent in formalin to the Yale University School of Medicine. RESULTS: Detailed dissection was performed under loupe magnification. Presumed structures were photographed in situ and biopsied. The thyroid was identified deep to the strap muscles, received its blood supply from the inferior and superior thyroid arteries and was blue in color. The right recurrent laryngeal nerve, identified and photographed in situ for the first time in the rhinoceros, was deep to the inferior thyroid artery and was traced throughout its cervical course. Single parathyroid glands identified on the lateral thyroid lobes received their blood supply from the inferior thyroid arteries and were confirmed histologically. They appear to be the largest parathyroids yet identified in the rhinoceros with estimated weights of 6,280 and 11,000 mg, respectively. Although the etiology of the parathyroid gland enlargement is unknown, the specimen has been preserved recapitulating the dissection performed by Sir Richard Owen. CONCLUSION: The parathyroids, thyroid and recurrent laryngeal nerve were identified in an Indian rhinoceros. This appears to be the first display of the rhinoceros recurrent laryngeal nerve in situ, and the parathyroid glands are the largest yet identified in the rhinoceros.

Dynamic Optical Contrast Imaging.

The variable location and indistinct features of parathyroid glands can make their intraoperative identification challenging. Currently, there exists no routine use of localization methods during surgery. Dynamic optical contrast imaging (DOCI) leverages a novel realization of temporally dependent measurements of tissue autofluorescence that allows the acquisition of specific tissue properties. A prospective series of patients with primary hyperparathyroidism was examined. Parathyroid lesions and surrounding tissues were collected; fluorescence decay images were acquired via DOCI. Ex vivo samples (81 patients) were processed for histologic assessment. DOCI extracts relative fluorescence decay information in a surgically relevant field of view with a clinically accessible acquisition time <2 minutes. Analysis of DOCI revealed microscopic characterization sufficient for tissue type identification consistent with histology ( P < .05). DOCI is capable of efficiently distinguishing parathyroid tissue from adjacent tissues. Such an intraoperative tool would be transformative, helping surgeons to identify lesions, preserve healthy tissue, and improve patient outcomes.

Differences in single gland and multigland disease are seen in low biochemical profile primary hyperparathyroidism.

BACKGROUND: Primary hyperparathyroidism is characterized by increased levels of serum calcium and parathyroid hormone. Recently, 2 additional mild biochemical profiles have emerged, normocalcemic and normohormonal primary hyperparathyroidism. We reviewed our surgical experience of mild biochemical profile patients and compared them with classic primary hyperparathyroidism patients. METHODS: This is a single institution, retrospective cohort review of all patients who underwent parathyroidectomy for primary hyperparathyroidism from 2006-2012. Preoperative and intraoperative variables were analyzed. Univariable analysis was performed with analysis of variance and the χ2 test. A logistic regression was performed to identify significantly independent predictor variables for multigland disease. RESULTS: A total of 573 patients underwent parathyroidectomy for primary hyperparathyroidism (classic, n = 405; normohormonal, n = 96; normocalcemic, n = 72). Normocalcemic primary hyperparathyroidism was associated with multigland disease in 43 (45%, P < .001) patients as compared with the normohormonal (7, 10%) and classic (36, 9%) groups. On logistic regression, significant predictors for multigland disease were the normocalcemic subtype and positive family history. Twelve month biochemical normalization rates after operative treatment were >98% in all 3 groups. CONCLUSION: Our series shows that normocalcemic primary hyperparathyroidism is associated with a high incidence of multigland disease. Normohormonal disease is similar to classic disease patients with >90% presenting with single adenomas. Excellent rates of biochemical normalization can be obtained by operative treatment in all 3 groups.

Location of abnormal parathyroid glands: lessons from 810 parathyroidectomies.

BACKGROUND: Primary hyperparathyroidism (pHPT) is commonly treated with targeted parathyroidectomy (PTX) guided by preoperative imaging and intraoperative parathormone monitoring. Despite advanced imaging techniques, failure of parathyroid localization still occurs. This study determines the anatomical distribution of single abnormal parathyroid glands, which may help direct the surgeon in PTX when preoperative localization is unsuccessful. METHODS: A retrospective review of prospectively collected data of 810 patients with pHPT who underwent initial PTX at a tertiary medical center was performed. All patients had biochemically confirmed pHPT and single-gland disease. Abnormal parathyroid gland localization was determined at time of operation, correlated with operative and pathology reports, and confirmed by operative success defined as eucalcemia for ≥6 mo after PTX. Patients with multiple endocrine neoplasia, secondary, tertiary, or familial hyperparathyroidism, multiglandular disease, parathyroid cancer, and ectopic glands were excluded. Data were analyzed by chi-square and Z-test analyses. RESULTS: Among 810 patients who underwent PTX for pHPT, single abnormal parathyroid glands were unequally distributed among the four eutopic locations (left superior, 15.7%; left inferior, 31.3%; right superior, 15.8%; right inferior, 37.2%; P < 0.01). Abnormal inferior parathyroid glands (68.5%) were significantly more common than abnormal superior glands (31.5%), respectively (P < 0.01). In men, the most common location for single abnormal parathyroid glands was the right inferior position (43.4%, P < 0.01). Overall, there was no significant difference in laterality. CONCLUSIONS: This large series of patients suggests that single eutopic abnormal parathyroid glands are more likely to be inferior. In men, moreover, if an abnormal parathyroid gland is not localized preoperatively, the right inferior location should be explored first. Nevertheless, successful PTX remains predicated on knowledge of parathyroid anatomy, experience, and judgment of the surgeon.

The Essentials of Parathyroid Hormone Venous Sampling.

Hyperparathyroidism is an excess of parathyroid hormone in the blood due to over-activity of one or more parathyroid gland. Localization of abnormal glands with noninvasive imaging modalities, such as technetium sestamibi scan and cross-sectional imaging, has a high success rate. Parathyroid venous sampling is performed for patients with persistent or recurrent disease after previous parathyroid surgery, when repeat noninvasive imaging studies are negative or discordant. The success of invasive localization studies and results interpretation is dependent on the interventional radiologist's understanding of the normal and ectopic anatomic locations of parathyroid glands, as well as their blood supply and venous drainage. Anatomic and technical considerations for selective parathyroid venous sampling are reviewed.

Nuclear Medicine Methods for Evaluation of Abnormal Parathyroid Glands in Patients with Primary and Secondary Hyperparathyroidism.

Considered rare disease in the past, primary hyperparathyroidism (PHPT) has dramatically increased in incidence over the past thirty years with the introduction of routine calcium measurements; it is now approximately 42 per 100 000 persons. By far, the most common lesion found in patients with PHPT is the solitary parathyroid adenoma, occurring in 85%-90% of patients, while in the rest 10%- 15% primary hyperplasia of the parathyroid glands is present. Currently, the most widely used surgical approach is minimally invasive parathyroidectomy which is associated with less post-surgery complications and shorter operation time. To be successful this procedure needs to rely on a precise preoperative localization of the abnormal parathyroid glands, hence preoperative parathyroid imaging gained so large importance. The rationale for locating abnormal parathyroid tissue prior to surgery is that the glands can be notoriously unpredictable in their location. There is a general consensus that the best imaging procedure identifying abnormal parathyroid glands is the preoperative scintigraphy with 99mTc-sestamibi or 99mTc-tetrofosmin. It is characterized with high sensitivity and specificity exceeding those of ultrasound, CT or MRI. Combining scintigraphy with the other imaging techniques increases the precision for topic localization.