Epidemiology and Diagnosis of Hypoparathyroidism

Epidemiology of parathyroid disorders

Parathyroid disorders are not as uncommon as once believed. Both hyper- and hypoparathyroidism are more prevalent in women, but for different reasons. The female preponderance seen in primary hyperparathyroidism may be pathogenically linked, as it is more common after menopause. By contrast, higher prevalence of hypoparathyroidism in women is related to thyroid surgery, which is performed more frequently in women; thus the female to male ratio of hyper- and hypoparathyroidism is about 3:1 and 4:1 respectively. For similar reasons, the mean age of patients with hypoparathyroidism, on average, is a decade lower than that of patients with primary hyperparathyroidism. Furthermore, primary hyperparathyroidism is the third most common endocrine disorder after diabetes and thyroid disorders, but the prevalence of hypoparathyroidism is about 34 fold lower than that of primary hyperparathyroidism. Current epidemiological data is reasonable for primary hyperparathyroidism, but inadequate for hypoparathyroidism. Further concerted efforts should be undertaken to better define the distribution, determinants and disease burden of both disorders in order to prioritize practice guidelines, disease management strategies, and research agendas.

Epidemiology and Complications of Hypoparathyroidism

Until recently, very few studies have described the epidemiology of this rare disorder. Several large population-based studies have recently been published describing the prevalence and incidence of hypoparathyroidism in various countries. Some of these studies have described the epidemiology of both postsurgical and nonsurgical hypoparathyroidism. In addition, a number of studies have now been published describing the prevalence of complications of this disorder. This article summarizes the published medical literature regarding the prevalence and incidence of this disorder, and the risk of known complications of hypoparathyroidism.

Causes and pathophysiology of hypoparathyroidism

Hypoparathyroidism, a disorder characterized by hypocalcemia ensuing from inadequate parathyroid hormone secretion, is a rather rare disorder caused by multiple etiologies. When not caused by inadvertent damage or removal of the parathyroids during neck surgery, it is usually genetically determined. Epidemiological figures of this disease are still scarce and mainly limited to countries where non-anonymous databases are available and to surgical case series. Both the surgical and non-surgical forms pose diagnostic challenges. For surgical hypoparathyroidism, transient forms have to be ruled out even in the long term, in order to avoid unnecessary chronic replacement therapy with calcium and calcitriol. Regarding non-surgical hypoparathyroidism, once referred to as idiopathic, a systematic clinically and genetically-driven approach to define the precise diagnosis have to be pursued. In the case of syndromic hypoparathyroidism, patients have to be screened for associated abnormalities. Autoimmune, non-genetic hypoparathyroidism is still a diagnosis of exclusion, since no specific autoantibodies are specific for this condition.

Surgical Hypoparathyroidism

Surgical hypoparathyroidism is the most common cause of hypoparathyroidism and the result of intentional or inadvertent extirpation, trauma, or devascularization of the parathyroid glands. Surgical hypoparathyroidism may present as a medical emergency. Pediatric patients, those with Graves disease, and those undergoing extensive neck dissections or reoperative neck surgery are at particular risk for this complication. Extensive surgical expertise, immediate or delayed autotransplantation, and prophylactic and postoperative calcium/vitamin D supplementation in select patients are associated with a reduction in the risk of surgical hypoparathyroidism. Intraoperative parathyroid imaging is among novel strategies being investigated to mitigate surgical hypoparathyroidism in the intraoperative setting.

Conventional Treatment of Hypoparathyroidism

Conventional therapy of hypoparathyroidism consists of oral calcium and either activated vitamin D or vitamin D supplements at varying doses. Although adjusting dosing of calcium and/or activated vitamin D or vitamin D itself, the serum calcium should be obtained weekly or monthly depending on the clinical situation. Calcium supplementation in hypoparathyroidism usually consists of calcium carbonate because it is 40% elemental calcium by weight. However, calcium citrate (21% elemental calcium) is indicated for patients with achlorhydria and proton pump inhibitor therapy. Many clinicians prefer to uptitrate the activated form of vitamin D to reduce the amount of calcium supplementation.

Cranio-Maxillofacial and Dental Findings in Albright's Hereditary Osteodystrophy and Pseudohypoparathyroidism

INTRODUCTION

The clinical phenotype of pseudohypoparathyroidism (PHP) is caused by Albright's Hereditary Osteodystrophy (AHO). Often, "round face" the only facial clinical sign reported in the literature. The aim of this study was to highlight various cranio-maxillofacial clinical findings associated with AHO.

RESULTS

Four patients presented with PHP type 1a. Only one patient exhibited the classical round face. All patients exhibited dental anomalies, class III malocclusion with maxillary retrusion, and a copper beaten appearance of the skull. One suffered from craniosynostosis.

CONCLUSION

The frequency of craniofacial and dental features associated with malocclusion should prompt careful follow-up, particularly during facial growth, in patients with AHO.

Heterozygous Mutations in TBX1 as a Cause of Isolated Hypoparathyroidism

Context

Most cases of autosomal dominant isolated hypoparathyroidism are caused by gain-of-function mutations in CASR or GNA11 or dominant negative mutations in GCM2 or PTH.

Objective

To identify the genetic etiology for dominantly transmitted isolated hypoparathyroidism in two multigenerational families with 14 affected family members.

Methods

We performed whole exome sequencing of DNA from two families and examined the consequences of mutations by minigene splicing assay.

Results

We discovered disease-causing mutations in both families. A splice-altering mutation in TBX1 (c.1009+1G>C) leading to skipping of exon 8 (101 bp) was identified in 10 affected family members and five unaffected subjects of family A, indicating reduced penetrance for this point mutation. In a second family from France (family B), we identified another splice-altering mutation (c.1009+2T>C) adjacent to the mutation identified in family A that results in skipping of the same exon; two subjects in family B had isolated hypoparathyroidism, whereas a third subject manifested the clinical triad of the 22q11.2 deletion syndrome, indicative of variable expressivity.

Conclusions

We report evidence that heterozygous TBX1 mutations can cause isolated hypoparathyroidism. This study adds knowledge to the increasingly expanding list of causative and candidate genes in isolated hypoparathyroidism.

Efficacy and safety of long-term management of patients with chronic post-surgical hypoparathyroidism

PURPOSE

To evaluate adherence to European Society of Endocrinology guidelines and risk of renal complications in patients with chronic post-operative hypoparathyroidism (PO-HypoPT) treated with calcium and activated vitamin D metabolites.

METHODS

We evaluated 90 adult patients (68 females and 22 males) with chronic (3 years) PO-HypoPT. Total albumin-corrected (Alb-Ca) and ionized serum calcium, phosphate, creatinine, PTH, and 24-h urinary calcium were measured; renal ultrasound was also performed. Healthy hospital employers (n = 142) were used as control.

RESULTS

Complete data were available in 82 patients. Twenty-eight (34.1%) met four targets (Alb-Ca, phosphate, calcium phosphate product and 24-h urinary calcium), 36 (43.9%) three, 17 (20.7%) two, and 1 (1.2%) one. Thirteen (14.4%) had Alb-Ca value below and 18 (20.0%) above the target range and 54.9% 24-h urinary calcium above the upper normal limit. Seven (7.7%) has increased serum phosphate and none an increased calcium phosphate product. Eleven (12.2%) patients had eGFR < 60 mL/min × 1.73 m². Nephrolithiasis was present in 27 (30%) patients. Compared with the controls, patients had lower Alb-Ca (8.9 ± 0.5 vs. 9.5 ± 0.3 mg/dL, P 0.0001) and a higher rate of kidney stones, mostly asymptomatic [27/90 (30%) vs 7/142 (5%), P < 0.0001, odd ratio 8.2 (3.4-19.9)]. Fifty-seven patients had ≥ four serum Ca²⁺ determinations during follow-up. Forty (70.2) patients had values within the target range in > 50% of cases, 18 in > 75%, and only 2 in 100%. Two patients never had values in the target range.

CONCLUSIONS

Treatment of chronic PO-HypoPT with calcium and activated vitamin D metabolites is suboptimal and associated with an increased risk of renal complications.

Hypocalcemic disorders

Calcium is vital for life, and extracellular calcium concentrations must constantly be maintained within a precise concentration range. Low serum calcium (hypocalcemia) occurs in conjunction with multiple disorders and can be life-threatening if severe. Symptoms of acute hypocalcemia include neuromuscular irritability, tetany, and seizures, which are rapidly resolved with intravenous administration of calcium gluconate. However, disorders that lead to chronic hypocalcemia often have more subtle manifestations. Hypoparathyroidism, characterized by impaired secretion of parathyroid hormone (PTH), a key regulatory hormone for maintaining calcium homeostasis, is a classic cause of chronic hypocalcemia. Disorders that disrupt the metabolism of vitamin D can also lead to chronic hypocalcemia, as vitamin D is responsible for increasing the gut absorption of dietary calcium. Treatment and management options for chronic hypocalcemia vary depending on the underlying disorder. For example, in patients with hypoparathyroidism, calcium and vitamin D supplementation must be carefully titrated to avoid symptoms of hypocalcemia while keeping serum calcium in the low-normal range to minimize hypercalciuria, which can lead to renal dysfunction. Management of chronic hypocalcemia requires knowledge of the factors that influence the complex regulatory axes of calcium homeostasis in a given disorder. This chapter discusses common and rare disorders of hypocalcemia, symptoms and workup, and management options including replacement of PTH in hypoparathyroidism.

Late diagnosis of pseudohypoparathyroidism in adulthood. Case series

Introduction: Pseudohypoparathyroidism (PHP) is a rare hereditary disease, characterized by hypocalcemia/hyperphosphatemia secondary to peripheral resistance to parathyroid hormone (PTH). PHP diagnosis is usually precluded since hypocalcemia is considered as the primary diagnosis, thus delaying further diagnostic studies and preventing an adequate management of this clinical condition.Materials and methods: Retrospective review of the databases of the Endocrinology departments of two tertiary care centers of Medellin, Colombia from January 2012 to December 2016. Patients diagnosed with PHP based on clinical presentation and confirmatory laboratory values were included.Results: Four patients met the inclusion criteria. All PHP cases were diagnosed in adulthood despite strong early clinical and laboratory evidence of the disease. Three patients were diagnosed with Fahr’s syndrome and two with Albright’s hereditary osteodystrophy. The mean values obtained were PTH of 376.8 pg/mL, calcium of 6.17 mg/dL and phosphorus of 6.55 mg/dL.Conclusions: PHP is a rare disorder. This paper describes four PHP cases diagnosed during adulthood. Emphasis should be placed on the judicious approach to the patient with hypocalcemia and hyperphosphatemia with increased PTH and normal renal function, since these symptoms strongly suggest a diagnosis of PHP.

Dengue fever manifesting with tetany as the first presentation of primary hypoparathyroidism: a case report

Background

Primary hypoparathyroidism is associated with diverse variety of symptomatology of hypocalcemia including seizures and tetany. We report a case of previously undiagnosed asymptomatic primary hypoparathyroidism with extensive basal ganglia calcifications presenting for the first time with hypocalcemic tetany during acute dengue infection. Although hypocalcemia is known to occur in dengue infection symptomatic hypocalcemia is very infrequent.

Case presentation

A 32 year old male with short stature who has undergone bilateral cataract surgery 2 years ago but who was otherwise healthy, presented with fever and generalized body aches of 3 days duration and carpal spasms/tetany occurring on the third day of the illness. He was diagnosed to have acute dengue fever along with severe hypocalcemia. Subsequent workup confirmed that the patient had primary hypoparathyroidism with extensive basal ganglia and cerebellar calcifications which was previously undiagnosed. His acute illness and hypocalcemia was managed successfully and was commenced on regular calcium supplementations to alleviate the hypocalcemic effects of his chronic illness.

Conclusion

Clinical features of hypocalcemia may not commonly manifest up to the same degree of severity of hypocalcemia in primary hypoparathyroidism even till late adulthood but potential early clues such as short stature and premature cataract should be actively investigated. Worsening of already existing hypocalcemia during acute dengue fever led to the ultimate diagnosis of primary hypoparathyroidism in this patient which was lifesaving.

Patients' views about parathyroid transplantation for post-thyroidectomy hypoparathyroidism

BACKGROUND

Permanent hypoparathyroidism (hypoPT) represents the most common postoperative complication associated with total thyroidectomy. Current treatment relies on high-dose calcium and/or vitamin D supplementation, but often this is insufficient and some patients remain symptomatic. Parathyroid allotransplantation is a new therapeutic option described recently in the literature. This study aims to investigate the patients' acceptability of parathyroid transplantation as a potential new treatment for hypoPT.

METHOD

Online survey of members of HypoParaUK, a support group for individuals affected by hypoPT.

RESULTS

Responses were received from 252 hypoPT patients. Majority declared to experience severe symptoms despite regular medical treatment. On a severity scale of 0-5, symptoms that were most troublesome were fatigue (3.8), low sense of well-being (3.5), and numbness/tingling (2.9). On a scale of 0-10, on average, their current quality of life (QoL) was 5 ± 3 and they expected this would improve to 7 ± 2 with correction of their hypoPT. Forty-four percent of patients were extremely interested in a potential technique involving intramuscular injection of parathyroid cell suspension compared to just 14% who were interested in the more invasive procedure of implantation of a parathyroid allograft into the forearm. The main concerns expressed were related to the possible need for immunosuppressive therapy.

CONCLUSION

Patients with severe symptomatic hypoPT seem interested to consider participation in a clinical trial exploring the feasibility and success rate of parathyroid transplantation.

Prevalence of Chronic Hypoparathyroidism in a Mediterranean Region as Estimated by the Analysis of Anonymous Healthcare Database

Epidemiological data on prevalence and incidence of chronic hypoparathyroidism are still scarce. This study aimed to establish prevalence of chronic hypoparathyroidism and incidence of surgical hypoparathyroidism using the analysis of electronic anonymous public health care database. Data referred to a 5-year period (2009-2013, Region of Tuscany, Italy, as a sample representative of the whole Mediterranean/European population, estimated mean population: 3,750,000 inhabitants) were retrieved by the analysis of pharmaceutical distribution dataset, containing data related to drugs reimbursed by public health system, hospital discharge and procedures codes, and ICD9 exemption codes for chronic diseases. The application of a specific algorithm was applied to indirectly identify people with chronic hypoparathyroidism as assuming chronic therapy with active vitamin D metabolites (AVDM). The number of people taking AVDM for a period equal to or longer than 6 months till the end of the study period, with ICD9 exemption code for hypoparathyroidism, and with a disease-related discharge code were identified. Within this restricted group, patients with chronic kidney disease and osteoporosis were excluded. The indirect estimate of chronic hypoparathyroidism in a European Mediterranean subpopulation by means of the analysis of chronic therapy with AVDM was 27/100,000 inhabitants (female:male ratio = 2.2:1), with a mean age of 63.5 ± 16.7 years. The risk of developing hypoparathyroidism after neck surgery was 1.5%. While the epidemiological approaches based on disease code and hospital discharge code greatly underestimates the prevalence of hypoparathyroidism, the indirect estimate of this disease through the analysis of prescriptions of AVDM in a European region is in line with the results of studies performed in other regions of the world.

Diagnosis and management of pseudohypoparathyroidism and related disorders: first international Consensus Statement

This Consensus Statement covers recommendations for the diagnosis and management of patients with pseudohypoparathyroidism (PHP) and related disorders, which comprise metabolic disorders characterized by physical findings that variably include short bones, short stature, a stocky build, early-onset obesity and ectopic ossifications, as well as endocrine defects that often include resistance to parathyroid hormone (PTH) and TSH. The presentation and severity of PHP and its related disorders vary between affected individuals with considerable clinical and molecular overlap between the different types. A specific diagnosis is often delayed owing to lack of recognition of the syndrome and associated features. The participants in this Consensus Statement agreed that the diagnosis of PHP should be based on major criteria, including resistance to PTH, ectopic ossifications, brachydactyly and early-onset obesity. The clinical and laboratory diagnosis should be confirmed by a molecular genetic analysis. Patients should be screened at diagnosis and during follow-up for specific features, such as PTH resistance, TSH resistance, growth hormone deficiency, hypogonadism, skeletal deformities, oral health, weight gain, glucose intolerance or type 2 diabetes mellitus, and hypertension, as well as subcutaneous and/or deeper ectopic ossifications and neurocognitive impairment. Overall, a coordinated and multidisciplinary approach from infancy through adulthood, including a transition programme, should help us to improve the care of patients affected by these disorders.

De novo a novel variant of CaSR gene in a neonate with congenital hypoparathyroidism

Autosomal-dominant hypocalcemia with hypercalciuria (ADHH) is a genetic disease characterized by hypoparathyroidism with hypercalciuria. Most patients with ADHH have calcium-sensing receptor (CaSR) gene mutations. The CaSR gene controls parathyroid secretions, and mutations in this gene can be detected via changes in serum calcium level. The activating mutation of the CaSR gene results in familial or sporadic ADHH. Most activating mutations of the CaSR gene are reportedly de novo missense mutations. This is the first case report of a novel activating variant of the CaSR gene in a neonate with congenital hypoparathyroidism with hypomagnesemia and hypercalciuria. We also report the 3-month follow-up management of the patient.

A Population-Based Study of the Epidemiology of Chronic Hypoparathyroidism

There are very few reports on the epidemiology of chronic hypoparathyroidism. A population-based study was undertaken to describe the prevalence and incidence of hypoparathyroidism in Tayside, Scotland. Data on biochemistry, hospital admissions, prescribing, and death records in Tayside, Scotland, from 1988 to 2015 were linked electronically. Patients with at least three serum albumin-corrected calcium concentrations below the reference range that were taken in an outpatient setting were included in the study. Patients with severe chronic kidney disease before low calcium were excluded from the study. Patients with hypocalcemia were included if they had either previous neck surgery/irradiation, a low serum parathyroid hormone (PTH), or were treated with vitamin D. Patients were identified as having either a postsurgical or a nonsurgical cause or had secondary hypoparathyroidism, eg, hypomagnesemia. Overall, 18,955 patients were identified with hypocalcemia. Of these, 222 patients had primary hypoparathyroidism, 116 with postsurgical and 106 with nonsurgical chronic hypoparathyroidism. In 2015, the prevalence of primary hypoparathyroidism was 40 per 100,000, with a rate of 23 and 17 per 100,000, respectively, for postsurgical and nonsurgical. Eighty percent of the former and 64% of the latter were female. The mean serum calcium at diagnosis was 1.82 mmol/L (SD ± 0.24) and the annual incidence varied from 1-4 per 100,000. Overall, 71% of patients were prescribed vitamin D and/or calcium, whereas activated vitamin D was used in 48% of postsurgical cases and 43% of nonsurgical cases. Thyroxine and/or hydrocortisone were prescribed in more than 90% of postsurgical and 64% of nonsurgical cases. In conclusion, the prevalence of nonsurgical chronic hypoparathyroidism was greater than previously reported using this population-based approach. Many had mild hypocalcemia and did not receive any treatment. © 2017 American Society for Bone and Mineral Research.

Primary hypoparathyroidism presenting as basal ganglia calcification secondary to extreme hypocalcemia

Hypoparathyroidism is a rare endocrine disorder characterized by low serum calcium and parathyroid hormone levels. The most common cause is parathyroid iatrogenic surgical removal. However, innumerous and rarer conditions can cause hypoparathyroidism. The authors describe a 27-year-old man that presented in emergency department with confusion, amnesia and decreased attention span. A cerebral computed tomography revealed bilateral extensive calcification in the basal ganglia. A complete work-up revealed low serum calcium, high serum phosphorus and low parathyroid hormone, leading to the diagnosis of idiopathic primary hypoparathyroidism. Initial intravenous therapy with calcium gluconate and calcitriol was administered, with clinical and analytical improvement. The authors describe a rare condition, with an exuberant cerebral presentation and extreme hypocalcemia, which did not directly correlate to the severity of symptoms. Not only this is a treatable disorder that may have catastrophic results if overlooked but also its symptoms may be completely reversed with prompt treatment.

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.

Proceedings of the 2017 Santa Fe Bone Symposium: Insights and Emerging Concepts in the Management of Osteoporosis

The 18th Annual Santa Fe Bone Symposium was held on August 4-5, 2017, in Santa Fe, New Mexico, USA. The symposium convenes health-care providers and clinical researchers to present and discuss clinical applications of recent advances in research of skeletal diseases. The program includes lectures, oral presentations by endocrinology fellows, case-based panel discussions, and breakout sessions on topics of interest, with emphasis on participation and interaction of all participants. Topics included the evaluation and treatment of adult survivors with pediatric bone diseases, risk assessment and management of atypical femur fractures, nonpharmacologic strategies in the care of osteoporosis, and skeletal effects of parathyroid hormone with opportunities for therapeutic intervention. Management of skeletal complications of rheumatic diseases was discussed. Insights into sequential and combined use of antiresorptive agents were presented. Individualization of patient treatment decisions when clinical practice guidelines may not be applicable was covered. Challenges and opportunities with osteoporosis drug development were discussed. There was an update on progress of Bone Health TeleECHO (Bone Health Extension for Community Healthcare Outcomes), a teleconferencing strategy for sharing knowledge and expanding capacity to deliver best-practice skeletal health care.

Identification of a Novel Mutation in a Family with Pseudohypoparathyroidism Type 1a

Introduction

Pseudohypoparathyroidism type 1a is caused by GNAS mutations leading to target organ resistance to multiple hormones rather than parathyroid hormone, resulting not only in hypocalcemia, but also in Albright's hereditary osteodystrophy phenotype.

Materials and Methods

DNA sequencing of the GNAS gene identified a novel heterozygous mutation in peripheral blood leukocytes in the family presented in this case report.

Results

We present a case of a 25-year-old woman with pseudohypoparathyroidism type 1a admitted with seizures, whose family presents an autosomal dominant transmission of a novel heterozygous GNAS mutation (c.524_530+3del).

Conclusion

Pseudohypoparathyroidism type 1a is mostly caused by inactivating GNAS mutations that have been gradually reported in the literature that lead to a typical and complex clinical phenotype and resistance to multiple hormones. The deletion caused by the mutation identified in the presented case has not been reported previously.

Incidence of parathyroid disorders in Indian adult male population: A 25-year follow-up study

CONTEXT AND OBJECTIVE

Detailed information on the epidemiology of parathyroid disorders in India is lacking. Most of the available data pertain to primary hyperparathyroidism (PHPT) rather than the overall burden of parathyroid disorders. We studied the incidence of parathyroid disorders in a cohort of service personnel followed for a long duration.

DESIGN, SETTING AND PATIENTS

The data for this retrospective, descriptive epidemiological study were derived from the electronic medical records (EMR) of health care personnel enrolled between 1990 and 2015. Subjects were recruited between the ages of 17 and 20 years in good health, and the data pertaining to parathyroid disorders were derived from the EMR.

MAIN OUTCOMES MEASURES

We calculated the incidence rates per person-years of parathyroid disorders using appropriate statistical methods.

RESULTS

Our analysis includes 51 217 participants (median age 33, range 17-54 years) with a mean follow-up of 12.5 years. Yearly evaluation of the data gave cumulative follow-up duration of 613 925 person-years. PHPT was diagnosed in 37 patients and hypoparathyroidism in 16 patients, giving incidence rates of 6 and 2.6 per 100 000 person-years, respectively. Only one patient was diagnosed with pseudohypoparathyroidism (0.16 per 100 000 person-years). Of the 37 patients with PHPT, 16 (43%) developed postsurgical hypoparathyroidism.

CONCLUSIONS

Our cohort had a low incidence of PHPT when compared to Western populations. Long-term epidemiological studies are essential to identify the demographic trends of metabolic bone disorders in India.

[Not Available]

Parathormone (PTH), produced by parathyroid glands, is the main regulator of calcium homeostasis. Hypoparathyroidism (hypoPT), due to decrease of PTH production, is a rare disease. Symptoms are multiple, altering function of several organs and leading to a decrease of quality of life. Acquired etiologies, including thyroïdectomy, the main cause of hypoPT, can be distinguished from congenital etiologies, including genetic defects. HypoPT, which is classically treated by supplementation by calcium and active vitamin D, can now be treated by recombinant injection in certain indications as a poor control under classical therapy. Here are summarized current knowledge on etiologies, epidemiology, clinical manifestations and management of hypoPT.

Hypoparathyroidism: disease update and new methods of treatment

Гипопаратиреоз характеризуется гипокальциемией при нормальном или низком уровне паратиреоидного гормона (ПТГ). ПТГ регулирует уровень кальция в крови, влияя на реабсорбцию кальция и фосфора в почках, а также витамин D-зависимое всасывание кальция из желудочно-кишечного тракта. Наиболее распространенной причиной гипопаратиреоза является повреждение околощитовидных желез в ходе хирургического вмешательства в области шеи, в основном по поводу заболеваний щитовидной железы. Стандартные методы лечения включают в себя назначение препаратов кальция и витамина D для поддержания уровня кальция на нижней границе референсного интервала с целью предупреждения гиперкальциурии. Однако в ряде случаев компенсация гипокальциемии требует использования высоких доз препаратов кальция и витамина D, что сопровождается выраженным колебанием уровня кальция крови, внескелетной кальцификацией и ухудшением функции почек. В настоящее время наиболее перспективным методом лечения гипопаратиреоза является заместительная терапия рекомбинантным человеческим ПТГ(1-84), который представляет собой полноразмерный ПТГ. ПТГ(1-84) способствует поддержанию стойкой нормокальциемии, улучшая качество жизни пациентов. Однако влияние ПТГ(1-84) на функцию почек, костный обмен и профилактику других осложнений гипопаратиреоза требует дальнейшего изучения.

Hypoparathyroidism

Hypoparathyroidism is a disease characterized by inadequately low circulating concentrations of parathyroid hormone (PTH) resulting in low calcium levels and increased phosphate levels in the blood. Symptoms of the disease result from increased neuromuscular irritability caused by hypocalcaemia and include tingling, muscle cramps and seizures. The most common cause of the disease is inadvertent removal of, or injury to, the parathyroid glands during neck surgery, followed by genetic, idiopathic and autoimmune aetiologies. Conventional treatment includes activated vitamin D and/or calcium supplements, but this treatment does not fully replace the functions of PTH and can lead to short-term problems (such as hypocalcaemia, hypercalcaemia and increased urinary calcium excretion) and long-term complications (which include nephrocalcinosis, kidney stones and brain calcifications). PTH replacement has emerged as a new treatment option. Clinical trials using human PTH(1-34) and PTH(1-84) showed that this treatment was safe and effective in studies lasting up to 6 years. Recombinant human PTH(1-84) has been approved in the United States and Europe for the management of hypoparathyroidism; however, its effect on long-term complications is still being evaluated. Clinical practice guidelines, which describe the consensus of experts in the field, have been published and recognize the need for more research to optimize care. In this Primer, we summarize current knowledge of the prevalence, pathophysiology, clinical presentation and management of hypoparathyroidism.

Long-term outcome of cataract surgery in patients with idiopathic hypoparathyroidism and its relationship with their calcemic status

Cataract is a cardinal manifestation of hypoparathyroidism. Although patients with hypoparathyroidism require cataract surgery at a younger age than individuals without hypoparathyroidism, there is limited information on the outcome of this surgery. We assessed long-term complications of cataract surgery in patients with idiopathic hypoparathyroidism (IH) and its relationship with their clinical and biochemical parameters. Twenty-seven patients with IH and 25 nonhypoparathyroid controls with a minimum follow-up of 2 years after cataract surgery were assessed for visual acuity, intraocular pressure, lens centricity, Nd:YAG laser capsulotomy, and the severity of posterior capsular opacification (PCO) and anterior capsular opacification. High-resolution optical slit-lamp images were analyzed by an ophthalmologist. Patients with IH had cataract surgery at a younger age than controls (34.0 ± 16.4 years vs 58.0 ± 11.2 years, P < 0.001). A higher proportion of IH patients had dense white PCO (75.0 % vs 39.4 %, P = 0.004), Nd:YAG laser capsulotomy (44.2 % vs 10.0 %, P = 0.001), anterior capsular opacification (97.7 % vs 84.2 %, P = 0.03), and a decentric lens (28.3% vs 2.6 %, P = 0.001) at a comparable time after surgery (8.6 ± 6.1 years vs 8.7 ± 6.8 years, P = 0.85). On regression analysis, the severity of PCO in IH correlated only with male sex and not with other factors, including serum total calcium and inorganic phosphorus levels at the baseline and during follow-up. To conclude, patients with IH are likelier than individuals without IH to develop PCO and to require Nd:YAG laser capsulotomy after cataract surgery. Proper precautions should be taken during surgery to minimize this complication in IH.

Exome Sequencing Reveals Mutations in AIRE as a Cause of Isolated Hypoparathyroidism

Context

Most cases of autosomal recessive hypoparathyroidism (HYPO) are caused by loss-of-function mutations in GCM2 or PTH.

Objective

The objective of this study was to identify the underlying genetic basis for isolated HYPO in a kindred in which 3 of 10 siblings were affected.

Subjects

We studied the parents and the three adult affected subjects, each of whom was diagnosed with HYPO in the first decade of life.

Methods

We collected clinical and biochemical data and performed whole exome sequencing analysis on DNA from the three affected subjects after negative genetic testing for known causes of HYPO.

Results

Whole exome sequencing followed by Sanger sequencing revealed that all three affected subjects were compound heterozygous for two previously reported mutations, c.967_979delCTGTCCCCTCCGC:p.(L323SfsX51) and c.995+(3_5)delGAGinsTAT, in AIRE, which encodes the autoimmune regulator protein that is defective in autoimmune polyglandular syndrome type 1 (APS-1). Each parent carries one mutation, and all of the children of the patients are either heterozygous for one mutation or wild type. The affected sister developed premature ovarian failure, but the two affected brothers have no other features of APS-1 despite elevated serum levels of anti-interferon-α antibodies.

Conclusions

Our findings indicate that biallelic mutations in AIRE can cause isolated HYPO as well as syndromic APS-1. The presence of antibodies to interferon-α provides a highly sensitive indicator for loss of AIRE function and represents a useful marker for isolated HYPO due to AIRE mutations.

Proceedings of the 2016 Santa Fe Bone Symposium: New Concepts in the Management of Osteoporosis and Metabolic Bone Diseases

The Santa Fe Bone Symposium is an annual meeting of healthcare professionals and clinical researchers that details the clinical relevance of advances in knowledge of skeletal diseases. The 17th Santa Fe Bone Symposium was held in Santa Fe, New Mexico, USA, on August 5-6, 2016. The program included plenary lectures, oral presentations by endocrinology fellows, meet-the-professor sessions, and panel discussions, all aimed to provide ample opportunity for interactive discussions among all participants. Symposium topics included recent developments in the translation of basic bone science to patient care, new clinical practice guidelines for postmenopausal osteoporosis, management of patients with disorders of phosphate metabolism, new and emerging treatments for rare bone diseases, strategies to enhance fracture healing, and an update on Bone Health Extension for Community Healthcare Outcomes, using a teleconferencing platform to elevate the level of knowledge of healthcare professionals in underserved communities to deliver best practice care for skeletal diseases. The highlights and important clinical messages of the 2016 Santa Fe Bone Symposium are provided herein by each of the faculty presenters.

The Epidemiology of Hypoparathyroidism in Italy: An 8-Year Register-Based Study

Hypoparathyroidism is a rare endocrine disorder, but few studies have focused on the epidemiology and hospital management of the disease and none has been performed in Italy. We investigated the prevalence of different forms of hypoparathyroidism among hospitalized patients in Italy during an 8-year period. This study is designed as a retrospective register-based study. We retrieved data from the "Record of Hospital Discharge" (SDO) of the Italian Health Ministry, from the year 2006 to 2013 and analyzed the codes corresponding to hypoparathyroidism-related diagnoses. The inpatient prevalence of the disease was also calculated after excluding repeated hospitalizations. Overall, 27,692 hospitalization episodes for hypoparathyroidism were identified during the entire period (72.2% in women and 27.8% in men; mean age 49.5 ± 22.9 years). The mean length of stay was 7.4 ± 9.8 days (25.9% of the episodes requiring less than 3 days of stay). The mean hospitalization rate for hypoparathyroidism was 5.9/100,000 inhabitants per year and there was a significant decrease during the period of 2006-2013 (p < 0.0001). The mean hospitalization rate for postsurgical hypoparathyroidism was 1.4/100,000 inhabitants per year and the trend showed a significant reduction during the years (p < 0.0001). The mean prevalence of hypoparathyroidism among inpatients was 5.3/100,000 inhabitants per year, and there was a significant decrease over the years (p < 0.0001). Hypoparathyroidism, particularly the postsurgical form of the disease, is not an uncommon condition among hospitalized patients in Italy. We observed a tendency to a decrease in the frequency of hospitalization during the period 2006-2013.

Hypothyroidism associated with parathyroid disorders

Hypothyroidism may occur in association with congenital parathyroid disorders determining parathyroid hormone insufficiency, which is characterized by hypocalcemia and concomitant inappropriately low secretion of parathormone (PTH). The association is often due to loss of function of genes common to thyroid and parathyroid glands embryonic development. Hypothyroidism associated with hypoparathyroidism is generally mild and not associated with goiter; moreover, it is usually part of a multisystemic involvement not restricted to endocrine function as occurs in patients with 22q11 microdeletion/DiGeorge syndrome, the most frequent disorders. Hypothyroidism and hypoparathyroidism may also follow endocrine glands' damages due to autoimmunity or chronic iron overload in thalassemic disorders, both genetically determined conditions. Finally, besides PTH deficiency, hypocalcemia can be due to PTH resistance in pseudohypoparathyroidism; when hormone resistance is generalized, patients can suffer from hypothyroidism due to TSH resistance. In evaluating patients with hypothyroidism and hypocalcemia, physical examination and clinical history are essential to drive the diagnostic process, while routine genetic screening is not recommended.

An Adult Case of Chromosome 22q11.2 Deletion Syndrome Associated with a High-positioned Right Aortic Arch

Chromosome 22q11.2 deletion syndrome (22q11.2 DS) has a very wide phenotypic spectrum that includes dysmorphic features, cardiac anomalies, and hypocalcemia arising from hypoparathyroidism. We herein describe an adult case of 22q11.2 DS with associated hypoparathyroidism and anomalies of the aortic arch. Because the patient had been diagnosed with primary hypoparathyroidism at another hospital, a diagnosis of 22q11.2 DS had been overlooked. A chest X-ray examination revealed widening of the mediastinum caused by a high-positioned right aortic arch, and we subsequently confirmed a diagnosis of 22q11.2 DS using fluorescence in situ hybridization. Because primary hypoparathyroidism is a rare disorder, physicians should be aware of the variable phenotypic features of 22q11.2 DS.

Management of Hypoparathyroidism: Summary Statement and Guidelines

OBJECTIVE

Hypoparathyroidism is a rare disorder characterized by hypocalcemia and absent or deficient PTH. This report presents a summary of current information about epidemiology, presentation, diagnosis, clinical features, and management and proposes guidelines to help clinicians diagnose, evaluate, and manage this disorder.

PARTICIPANTS

Participants in the First International Conference on the Management of Hypoparathyroidism represented a worldwide constituency with acknowledged interest and expertise in key basic, translational, and clinical aspects of hypoparathyroidism. Three Workshop Panels were constituted to address questions for presentation and discussion at the Conference held in Florence, Italy, May 7-9, 2015. At that time, a series of presentations were made, followed by in-depth discussions in an open forum. Each Workshop Panel also met in closed sessions to formulate the three evidence-based reports that accompany this summary statement. An Expert Panel then considered this information, developed summaries, guidelines, and a research agenda that constitutes this summary statement.

EVIDENCE

Preceding the conference, each Workshop Panel conducted an extensive literature search as noted in the individual manuscripts accompanying this report. All presentations were based upon the best peer-reviewed information taking into account the historical and current literature.

CONSENSUS PROCESS

This report represents the Expert Panel's synthesis of the conference material placed in a context designed to be relevant to clinicians and those engaged in cutting-edge studies of hypoparathyroidism.

CONCLUSIONS

This document not only provides a summary of our current knowledge but also places recent advances in its management into a context that should enhance future advances in our understanding of hypoparathyroidism.

Review of Hypoparathyroidism

Hypoparathyroidism is a rare endocrine disorder in which parathyroid hormone (PTH) production is abnormally low or absent, resulting in low serum calcium and increased serum phosphorus. The most common cause of hypoparathyroidism is parathyroid gland injury or inadvertent removal during thyroid surgery. Current treatments include supplementation with calcium and active vitamin D, with goal albumin-corrected serum calcium level in the low-normal range of 8-9 mg/dl. Complications of the disease include renal dysfunction, nephrocalcinosis, kidney stones, extracellular calcifications of the basal ganglia, and posterior subcapsular cataracts, as well as low bone turnover and increased bone density. Until January 2015, hypoparathyroidism was the only classic endocrine disease without an available hormone replacement. Recombinant human PTH 1-84, full-length PTH, is now available for a selected group of patients with the disease who are not well controlled on the current standard therapy of calcium and active vitamin D. In addition, the role of PTH replacement on quality of life, intracerebral calcifications, cataracts, improving bone turnover, and reduction of renal complications of the disease remains to be further investigated.