Hypoparathyroidism

Hypoparathyroidism: diagnosis, management and emerging therapies

Hypoparathyroidism is characterized by inadequate parathyroid hormone (PTH) secretion or action and results in hypocalcaemia, and can lead to hyperphosphataemia and hypercalciuria. Most cases of hypoparathyroidism occur as a complication of surgery, with the remainder due to causes including autoimmune disease, genetic causes, infiltrative diseases, mineral deposition or due to abnormalities in serum levels of magnesium. Hypoparathyroidism can cause multisystem disease, with long-term complications resulting from ectopic calcification as well as renal complications with nephrocalcinosis, nephrolithiasis and renal impairment in addition to respiratory, cardiac or neurological manifestations. Conventional therapy consists of oral calcium salts and active vitamin D but it has limitations, including fluctuations in serum levels of calcium and a high pill burden, and can increase the risk of long-term complications. By contrast, PTH replacement therapy can effectively achieve normal serum levels of calcium, and lower serum levels of phosphate. The long-acting PTH analogue, palopegteriparatide, has been shown to normalize urine levels of calcium. In addition, PTH replacement therapy reduces the pill burden. Palopegteriparatide is also associated with improved quality of life in comparison to conventional therapy. This Review summarizes current recommendations regarding the pathophysiology, evaluation and management of hypoparathyroidism and also references the 2022 international hypoparathyroidism guidelines. Palopegteriparatide has now been approved as PTH replacement therapy for hypoparathyroidism. Emerging therapies will also be presented in this Review.

Skeletal health status among patients with chronic hypoparathyroidism: results from the Canadian National Hypoparathyroidism Registry (CNHR)

In the CNHR study, 35% of postmenopausal women had osteoporosis by BMD or fragility fracture, and 4% had both. Three men ≥ 50 had osteoporosis by BMD or fragility fracture (33.3%; n = 3/9). This suggests that close follow-up of skeletal health is necessary in postmenopausal women, and men ≥ 50 with chronic HypoPT.

PURPOSE

Chronic hypoparathyroidism (HypoPT) has been associated with decreased bone turnover and abnormalities in bone mineral density (BMD), microarchitecture, and strength. Current guidelines do not recommend systematic evaluation of skeletal health in patients with chronic HypoPT. Our study assessed skeletal health in pre- and postmenopausal women with chronic HypoPT and adult men.

METHODS

This prospective study enrolled adults with chronic HypoPT from the Canadian National Hypoparathyroidism Registry. Clinical characteristics, bone fractures, biochemistry, and serum bone biomarkers were assessed at baseline. Skeletal health evaluation included assessments of fragility fractures, BMD at lumbar spine (LS), femoral neck (FN), total hip (TH), 1/3 radial sites, trabecular bone score (TBS), and bone biomarkers.

RESULTS

We present the baseline data of the patients enrolled in the registry. We analyzed a total of 101 patients: 18 men, 35 premenopausal, and 48 postmenopausal women. The mean (SD) age at the onset of HypoPT was 40.7 (16.8) years, and the average disease duration was 11.2 (8.6) years. The most common etiology was postsurgical (74.3% vs. 25.7% non-surgical). Most patients received calcium supplements (89%) and active vitamin D (80%) at baseline. No fragility fractures or low BMD were reported in premenopausal women. However, BMD at LS, FN, TH, and TBS were significantly lower in postmenopausal compared to premenopausal women.

CONCLUSIONS

Overall, 35% of postmenopausal women had osteoporosis by BMD or prior fragility fracture, and 4% had both. Three men ≥ 50 years had osteoporosis by BMD or fragility fracture (33.3%; n = 3/9). This study suggests that close follow-up of skeletal health is necessary in postmenopausal women with chronic HypoPT and men ≥ 50 years.

Management of autosomal dominant hypocalcemia type 1: Literature review and clinical practice recommendations

PURPOSE

Autosomal Dominant Hypocalcemia type 1 (ADH1), caused by gain-of-function variants in the calcium-sensing receptor (CASR), is characterized by a variable degree of hypocalcemia and hypercalciuria with inappropriately low PTH. The clinical spectrum is broad, ranging from being asymptomatic to presenting with severe clinical features of hypocalcemia and end-organ damage such as nephrolithiasis and intracerebral calcifications. Although the underlying pathophysiology is different, ADH1 patients are often managed as patients with 'classical' primary hypoparathyroidism, possibly leading to (exacerbation of) hypercalciuria. New treatments such as PTH analogues and calcilytics directly targeting the CASR are in the pipeline. Specific clinical guidance for treatment and monitoring of ADH1 patients is lacking. The purpose of this study is to provide a literature review on management of ADH1, including new therapies, and to formulate practice recommendations.

METHODS

We searched for articles and ongoing clinical trials regarding management of ADH1.

RESULTS

Forty articles were included. First we review the conventional treatment of ADH1, focusing on active vitamin D, calcium supplements, thiazide diuretics, phosphorus binders and dietary recommendations. In a second part we give an overview of studies with emerging treatments in ADH1: PTH analogues (PTH1-34, rhPTH1-84, TransCon PTH and others) and calcilytics (preclinical studies and clinical trials). In a third part we discuss literature findings regarding monitoring of ADH1 patients. Finally, we formulate clinical practice recommendations.

CONCLUSION

We provide an overview of conventional and new treatments for ADH1 patients. Based on these data, we propose practical recommendations to assist clinicians in the management of ADH1 patients.

Development and validation of risk prediction models for permanent hypocalcemia after total thyroidectomy in patients with papillary thyroid carcinoma

Hypocalcemia is a common complication and can be permanent in patients following total thyroidectomy (TT). The aim of this study was to identify factors associated with permanent hypocalcemia and to develop a validated risk prediction model for permanent hypocalcemia to assist surgeons in the appropriate follow-up of high-risk patients regarding supplemental therapy. We included data of 92 patients with papillary thyroid carcinoma (PTC) undergoing TT who were randomly allocated in a 7:3 ratio to a training set (n = 65) and validation set (n = 27). Univariate and multivariate logistic regression analyses revealed significant correlations of permanent hypocalcemia with parathyroid hormone (PTH) at postoperative month 1 (IM PTH), IM calcium (Ca), and IM phosphorus (P). These variables were constructed two models. Model 1 used the three indicators listed above; model 2 also included tumor, node, metastasis staging. The receiver operating characteristic (ROC) curve analysis showed that the areas under the curve (AUC) for models 1 and 2 were high for both the training set (0.905/0.913) and the validation set (0.894/0.800). Calibration curves showed good agreement between the incidence of permanent hypocalcemia estimated using the predictive models and the actual incidence. Model 1 may be more concise and convenient for clinical use.

Efficacy and Safety of TransCon PTH in Adults With Hypoparathyroidism: 52-Week Results From the Phase 3 PaTHway Trial

CONTEXT

Conventional therapy for hypoparathyroidism aims to alleviate symptoms of hypocalcemia but does not address insufficient parathyroid hormone (PTH) levels.

OBJECTIVE

Assess the long-term efficacy and safety of TransCon PTH (palopegteriparatide) for hypoparathyroidism.

DESIGN

Phase 3 trial with a 26-week, double-blind, placebo-controlled period followed by a 156-week, open-label extension (OLE).

SETTING

Twenty-one sites across North America and Europe.

PARTICIPANTS

A total of 82 adults with hypoparathyroidism were randomized and received study drug and 78 completed week 52.

INTERVENTION(S)

All OLE participants received TransCon PTH administered once daily.

MAIN OUTCOME MEASURE(S)

Multicomponent efficacy endpoint: proportion of participants at week 52 who achieved normal serum calcium (8.3-10.6 mg/dL) and independence from conventional therapy (≤600 mg/day of elemental calcium and no active vitamin D). Other efficacy endpoints included patient-reported outcomes and bone mineral density. Safety was assessed by 24-hour urine calcium and treatment-emergent adverse events.

RESULTS

At week 52, 81% (63/78) met the multicomponent efficacy endpoint, 95% (74/78) achieved independence from conventional therapy, and none required active vitamin D. Patient-reported outcomes showed sustained improvements in quality of life, physical functioning, and well-being. Mean bone mineral density Z-scores decreased toward age- and sex-matched norms from baseline to week 52. Mean (SD) 24-hour urine calcium excretion decreased from 376 (168) mg/day at baseline to 195 (114) mg/day at week 52. Most treatment-emergent adverse events were mild or moderate and none led to trial discontinuation during the OLE.

CONCLUSION

At week 52 of the PaTHway trial, TransCon PTH showed sustained efficacy, safety, and tolerability in adults with hypoparathyroidism.

Hypoparathyroidism: Similarities and differences between Western and Eastern countries

BACKGROUD

Hypoparathyroidism (hypoPT) is characterized by acute and chronic complications due to insufficient parathyroid hormone (PTH) production or action. Several management guidelines have been developed, but mostly based on evidence from Western countries. Data from Eastern countries have not been systematically compared with those from Western countries.

METHODS

Literatures regarding to the epidemiology, genetics, risk factors, clinical manifestations and therapies for hypoPT in Easten and Western countries, including China, South Korea, Japan, India, and USA, Canada, Italy, and etc., were searched through PubMed and CNKI. This review was officially endorsed by European Calcified Tissue Society (ECTS) board.

RESULTS

Postoperative hypoPT is the major form of hypoPT in both Western and Eastern countries. The genetic profiles and clinical features of hypoPT are similar in Eastern and Western countries. The most commonly used medications in Eastern countries are calcium and native vitamin D or active vitamin D analogues, similar to their Western counterparts. While PTH replacement therapy is not available and approved to use in most Eastern countries.

CONCLUSION

Physicians and surgeons should follow the guidelines on the management of thyroid nodules, taking more care of protecting parathyroid glands during surgery. The cross-talk between East and West in the management of hypoPT should be continued. Direct comparisons of the management strategies in patients with hypoPT between Eastern and Wester countries regarding to the morbidity, mortality, quality of life, optimal dosage, efficacies and side-effects of conventional therapies or newer medications, as well as pharmacogenetics and pharmacoeconomics, would be valuable.

Pediatric hypoparathyroidism: etiological and clinical evaluation in a tertiary center

PURPOSE

This study aims to evaluate the etiology, clinical presentation, and management of pediatric hypoparathyroidism in a tertiary center.

METHODS

A retrospective review was conducted on pediatric patients diagnosed with hypoparathyroidism at the Pediatric Endocrinology Clinic from March 2021 to June 2023. Data on demographic characteristics, presenting symptoms, laboratory findings, genetic analyses, and treatment outcomes were collected.

RESULTS

A total of 56 patients (31 females) were included. The median age at diagnosis of the patients was 5.5 years (range 0.04-17 years), and the median age of symptom onset was 5 years (range 0.04-16.5 years). The etiology was genetic and idiopathic in 39 patients (70.9%), with syndromic forms, familial isolated hypoparathyroidism, and hypomagnesemia identified. DiGeorge syndrome was present in 14 patients, making it the most common syndromic form. The syndromes associated with hypomagnesemia were those with mutations in the TRMP6 and CLDN16 genes. Sixteen patients (29.1%) had acquired causes, primarily post-thyroid surgery and autoimmune conditions. Common symptoms included muscle spasms (32.7%) and seizures (21.8%). Laboratory findings revealed a median serum calcium level of 6.7 mg/dL (3.8-8.5) and median serum phosphorus level of 7.7 (4.9-12.5) mg/dL. Treatment primarily involved calcitriol [The median dose of calcitriol is 25 ng/kg/day (range: 25-50 ng/kg/day)] and calcium [The median dose of calcium gluconate is 0.7 mL/kg (range: 0.5-1 mL/kg) and oral calcium is 1000 mg (range: 700-1300 mg)] supplementation. Intravenous calcium gluconate treatment was administered to 39 (70.6%) patients, oral calcium carbonate therapy was given to 16 (29.1%) patients, and calcitriol treatment was initiated for 51 (91.1%) patients. Complications such as nephrocalcinosis (7, 13.7%) and hypercalciuria (7, 13.7%) were observed in some patients.

CONCLUSION

This study emphasizes the significant genetic component, particularly syndromic, in pediatric hypoparathyroidism, highlighting the need for comprehensive genetic evaluation and a multidisciplinary approach for effective management, especially concerning complications. In this way, early and accurate diagnosis will reduce unnecessary tests, treatment approaches, and repeated hospital visits. Regular monitoring is essential to mitigate potential complications associated with long-term treatment.

PTH Substitution Therapy for Chronic Hypoparathyroidism: PTH 1-84 and Palopegteriparatide

PURPOSE OF REVIEW

to describe and compare the efficacy and safety of the main PTH treatments, namely PTH(1-84) and palopegteriparatide, for the management of hypoparathyroidism.

RECENT FINDINGS

neither PTH (1-84) nor PTH(1-34) have been shown a clear and consistent favorable impact on the 24 h urinary calcium excretion normalization, while the positive effect on quality of life is still debated. Recently, the Food & Drug Administration and the European Medicines Agency approved palopegteriparatide as the first true replacement therapy for hypoPT management. Palopegteriparatide is a prodrug of PTH(1-34), administered once daily, and designed to provide continuous exposure to released PTH over a 24-h dosing period. According to phase II and phase III studies, palopegteriparatide seems to fill the gaps identified in existing therapies for hypoPT. Palopegteriparatide is the first real replacement therapy for the management of hypoparathyroidism and seems to fill the gaps identified in existing therapies for hypoPT.

Three Siblings With Familial Isolated Hypoparathyroidism: A Diagnostic Journey From CASR to Novel GCM2 Variant

We report a patient who initially presented at 4 days old with hypocalcemia, hypoparathyroidism, and elevated phosphorous level. Treatment was initiated with calcitriol, calcium carbonate (CaCO3), vitamin D, and low phosphorous formula. Family history was positive for an activating calcium sensing receptor (CASR) variant (R990G) identified previously in 2 older siblings who were treated with CaCO3 and calcitriol. However, genetic studies were negative for the CASR variant in our patient. She maintained a large calcium requirement and was admitted for multiple episodes of hypocalcemia. Further investigation revealed that the CASR variant identified in the older siblings was now considered a benign, nondisease-causing variant. Whole exome sequencing on our proband revealed a homozygous pathogenic variant in the GCM2 gene (Gln392*) consistent with a molecular diagnosis of familial isolated hypoparathyroidism. Genetic studies revealed the 2 older siblings harbor the same genetic changes and parents are heterozygous carriers for this allele. Due to persistent hypocalcemia, we initiated teriparatide. She weaned off calcitriol and achieved normocalcemia on teriparatide, CaCO3, and vitamin D. Siblings transitioned to the same treatment without complications. These findings demonstrate the importance of adequate diagnostic genetic testing and the role of variant reanalysis over time in promoting accurate diagnoses.

Predictors of lumbar spine trabecular bone score in women with postsurgical hypoparathyroidism

Hypoparathyroidism is a rare disease that markedly reduces bone remodeling, leading to increased bone mineral density and changes in bone microarchitecture. However, it is currently unclear how these changes affect fracture risk. In this study, we investigated bone mass by dual-energy x-ray absorptiometry, the occurrence of morphometric vertebral fractures, and bone microarchitecture by assessing trabecular bone score in women with postsurgical hypoparathyroidism. We included 67 women with hypoparathyroidism aged 52.9 ± 12.3 years and 63 age- and body mass index-matched controls, which were assessed for femoral and lumbar spine bone mineral density, trabecular bone score, and vertebral fractures by dual-energy x-ray absorptiometry. Women with hypoparathyroidism had significantly higher bone mineral density at the lumbar spine, femoral neck, and total hip compared with controls despite similar trabecular bone score values. Vertebral fracture assessment indicated that two women with hypoparathyroidism presented vertebral fractures, both aged over 65 years. Conversely, no vertebral fractures were detected in control women. In a multivariate linear regression model, we found that older age, diabetes, and lower lumbar spine mineral density were significant predictors of lower trabecular bone score values. Our findings indicate that vertebral fractures are not common among women with postsurgical hypoparathyroidism aged under 65 years. Moreover, trabecular bone score values were similar in women with hypoparathyroidism and age-matched controls and were associated with traditional risk factors for fractures, such as older age, type 2 diabetes, and lower spine bone mineral density. LAY SUMMARY: Chronic parathyroid hormone deficiency decreases bone turnover and modifies skeletal properties, although the impact of these changes on fracture risk remains unclear. We studied 67 women with postsurgical hypoparathyroidism and 63 age and body mass index-matched healthy controls and found that bone mineral density is increased in women with hypoparathyroidism despite similar trabecular bone score values and a low occurrence of morphometric vertebral fractures. This suggests that the low bone turnover in hypoparathyroidism increases bone mass, but this is not accompanied by improved bone microarchitecture, indicating that trabecular bone score may be a valuable tool to complement the assessment of skeletal health and the risk of fractures in this condition.

Hypophysitis and central nervous system involvement in association with Sjögren's syndrome along with hypoparathyroidism: a case report

BACKGROUND

Patients with autoimmune diseases can develop multiple autoimmune diseases over a long period of time, and the presence of more than one autoimmune disease in a single patient is defined as polyautoimmunity. Polyautoimmunity may be clinical evidence that autoimmune diseases share similar immunological mechanisms.

CASE PRESENTATION

We report a 30-year-old woman with a unique combination of autoimmune diseases predominantly affecting the central nervous system, with hypoparathyroidism, hypophysitis, medulla involvement, and pons and temporal lobe involvement associated with primary Sjögren's syndrome (pSS), occurring independently over a long period. The patient who had a history of muscle cramps and one seizure incident, presented with vomiting and blurred vision. She was diagnosed with hypophysitis and hypoparathyroidism with calcifications in the basal ganglia and cerebellum. She recovered after four months of corticosteroid treatment for hypophysitis and was started on treatment for hypoparathyroidism. Eight months later, she developed vomiting, hiccups, vertigo, and ataxia with a focal lesion in the medulla. She recovered with immunosuppressive treatment for 2 years. Fifty-eight months after the onset of hypophysitis, she developed diplopia and dry mouth and eyes. MRI showed infiltrative lesions in the left pons and left temporal lobe. Based on positive anti-Sjögren's syndrome-related antigen A antibodies and low unstimulated whole salivary flow rate, pSS was diagnosed. She received corticosteroids and continued mycophenolate mofetil treatment with recovery of neurological symptoms.

CONCLUSION

This case highlights the need for long-term follow-up to detect autoimmune disease processes involving various organs.

Risk factors of transient and permanent hypoparathyroidism after thyroidectomy: a systematic review and meta-analysis

BACKGROUND

Postoperative hypoparathyroidism (hypoPT) is a common complication following thyroid surgery. However, current research findings on the risk factors for post-thyroid surgery hypoPT are not entirely consistent, and the same risk factors may have different impacts on transient and permanent hypoPT. Therefore, there is a need for a comprehensive study to summarize and explore the risk factors for both transient and permanent hypoPT after thyroid surgery.

MATERIALS AND METHODS

Two databases (PubMed and Embase) were searched from inception to 2024. The Newcastle-Ottawa Scale was used to rate study quality. Pooled odds ratios were used to calculate the relationship of each risk factor with transient and permanent hypoPT. Subgroup analyses were conducted for hypoPT with different definition-time (6 or 12 months). Publication bias was assessed using Begg's test and Egger's test.

RESULTS

A total of 19 risk factors from the 93 studies were included in the analysis. Among them, sex and parathyroid autotransplantation were the most frequently reported risk factors. Meta-analysis demonstrated that sex (female vs. male), cN stage, central neck dissection, lateral neck dissection, extent of central neck dissection (bilateral vs. unilateral), surgery [total thyroidectomy (TT) vs. lobectomy], surgery type (TT vs. sub-TT), incidental parathyroidectomy, and pathology (cancer vs. benign) were significantly associated with transient and permanent hypoPT. Preoperative calcium and parathyroid autotransplantation were only identified as risk factors for transient hypoPT, while preoperative PTH was a protective factor. Additionally, node metastasis and parathyroid in specimen were associated with permanent hypoPT.

CONCLUSION

The highest risk of hypoPT occurs in female thyroid cancer patients with lymph node metastasis undergoing TT combined with neck dissection. The key to preventing postoperative hypoPT lies in the selection of surgical approach and intraoperative protection.

Single-cell analysis reveals transcriptional dynamics in healthy primary parathyroid tissue

Studies on human parathyroids are generally limited to hyperfunctioning glands owing to the difficulty in obtaining normal human tissue. We therefore obtained non-human primate (NHP) parathyroids to provide a suitable alternative for sequencing that would bear a close semblance to human organs. Single-cell RNA expression analysis of parathyroids from four healthy adult M. mulatta reveals a continuous trajectory of epithelial cell states. Pseudotime analysis based on transcriptomic signatures suggests a progression from GCM2 hi progenitors to mature parathyroid hormone (PTH)-expressing epithelial cells with increasing core mitochondrial transcript abundance along pseudotime. We sequenced, as a comparator, four histologically characterized hyperfunctioning human parathyroids with varying oxyphil and chief cell abundance and leveraged advanced computational techniques to highlight similarities and differences from non-human primate parathyroid expression dynamics. Predicted cell-cell communication analysis reveals abundant endothelial cell interactions in the parathyroid cell microenvironment in both human and NHP parathyroid glands. We show abundant RARRES2 transcripts in both human adenoma and normal primate parathyroid cells and use coimmunostaining to reveal high levels of RARRES2 protein (also known as chemerin) in PTH-expressing cells, which could indicate that RARRES2 plays an unrecognized role in parathyroid endocrine function. The data obtained are the first single-cell RNA transcriptome to characterize nondiseased parathyroid cell signatures and to show a transcriptomic progression of cell states within normal parathyroid glands, which can be used to better understand parathyroid cell biology.

Quality of life in patients with hypoparathyroidism receiving standard treatment: an updated systematic review

PURPOSE

Hypoparathyroidism is defined by hypocalcemia with inappropriately normal or low parathyroid hormone levels. The current standard treatment consists of lifelong calcium and/ or vitamin D supplementation. Even while on stable treatment regimens, hypoparathyroid patients might still suffer from symptoms that can negatively impact their quality of life.

METHODS

A systematic literature review to identify the current knowledge regarding quality of life in patients with hypoparathyroidism receiving standard treatment was performed on November 1st, 2023. PubMed as well as Web of Science were searched. The systematic review is registered in PROSPERO (#CRD42023470924).

RESULTS

After removal of duplicates, 398 studies remained for title and abstract screening, after which 30 were included for full-text screening. After exclusion of seven studies with five studies lacking a control population, one using a non-validated questionnaire, and one being a subsample of the larger included study, 23 studies were included in this systematic review. The majority of the included studies used a guideline-conform definition of hypoparathyroidism, and the SF-36 was the most often applied tool. Almost all studies (87%) reported statistically significantly lower scores in at least one quality of life domain compared to a norm population or controls.

CONCLUSION

Patients with hypoparathyroidism receiving standard treatment report impairments in quality of life. The reasons for these impairments are probably multifaceted, making regular monitoring and the inclusion of various professionals necessary.

Endocrine manifestations in adults with 22q11.2 deletion syndrome: a retrospective single-center cohort study

INTRODUCTION AND OBJECTIVE

Patients with the 22q11.2 deletion syndrome (22q11DS) frequently display cardiological and psychiatric diseases, but are also at increased risk for endocrine manifestations. The aim of this study was to evaluate the screening, prevalence, and management of hypoparathyroidism and thyroid disease in patients with 22q11DS, to evaluate the metabolic profile, and to compare these results with current literature and guidelines.

DESIGN

We performed a retrospective study of patients with genetically confirmed 22q11DS, followed at the center for human genetics of the University Hospitals Leuven, resulting in a cohort of 75 patients. Medical history, medication, and laboratory results concerning hypoparathyroidism, thyroid dysfunction, and the metabolic profile were collected.

RESULTS

Of the total cohort, 26 patients (35%) had at least one hypocalcaemic episode. During hypocalcaemia, parathyroid hormone (PTH) was measured in only 12 patients with 11 having normal or low PTH, confirming a diagnosis of hypoparathyroidism. Recurrent episodes of hypocalcaemia occurred in seventeen patients (23%). Adherence to the guidelines was low, with 13% of patients having a yearly serum calcium evaluation, 12% receiving daily calcium supplements, and 20% receiving non-active vitamin D. Hypothyroidism was present in 31 patients (44%) and hyperthyroidism in 6 patients (8%). Information on body mass index (BMI) was available in 52 patients (69%), of which 38% were obese (BMI ≥ 30 kg/m2).

CONCLUSION

Hypoparathyroidism, hypothyroidism, and obesity are common endocrine manifestations in patients with 22q11DS but are probably underdiagnosed and undertreated, indicating the need for multidisciplinary follow-up including an endocrinologist.

Iatrogenic Hypoparathyroidism Development After Thyroidectomy: A Retrospective Cohort Study

BACKGROUND

Iatrogenic hypoparathyroidism is a common cause of postthyroidectomy hypocalcaemia. It has varying incidence rates after neck surgery in Saudi Arabia, ranging from 0.07% to 65.30%. Hypoparathyroidism can manifest with a spectrum of symptoms, ranging from mild to severe and life-threatening. This study aimed to assess the rate and predictors of iatrogenic hypoparathyroidism after thyroid surgery and its natural course.

METHODS

This retrospective cohort study used a data collection form to extract patient information from the electronic healthcare system (Best-Care) for patients treated from 2017 to 2022. Patients' demographics, surgical specifics and biochemical profiles were recorded for subsequent analysis.

RESULTS

Among the 343 patients who underwent thyroidectomy, 130 (37.9%) developed hypoparathyroidism, primarily within the first day after surgery. Calcium or vitamin D supplementation before surgery did not significantly influence hypoparathyroidism development. Notably, extensive combined lymph node dissection was significantly associated with postoperative hypoparathyroidism development (p = 0.0004). More patients who underwent central and lateral lymph node dissection (n = 19, 79.17%) developed hypoparathyroidism than patients who underwent central (n = 18, 40.91%) or lateral (n = 8, 38.10%) dissection alone. Permanent hypoparathyroidism was observed in 40 patients (11.66%).

CONCLUSION

This study revealed a high incidence of iatrogenic hypoparathyroidism and high rates of permanent hypoparathyroidism. Further research is warranted to better comprehend the risk factors and optimise management strategies for iatrogenic hypoparathyroidism. Overall, our findings emphasise the need for vigilant monitoring and effective management of patients undergoing thyroidectomy and the significance of postoperative replacement therapies.

Gallic acid pretreatment mitigates parathyroid ischemia-reperfusion injury through signaling pathway modulation

Thyroid surgery often results in ischemia-reperfusion injury (IRI) to the parathyroid glands, yet the mechanisms underlying this and how to ameliorate IRI remain incompletely explored. Our study identifies a polyphenolic herbal extract-gallic acid (GA)-with antioxidative properties against IRI. Through flow cytometry and CCK8 assays, we investigate the protective effects of GA pretreatment on a parathyroid IRI model and decode its potential mechanisms via RNA-seq and bioinformatics analysis. Results reveal increased apoptosis, pronounced G1 phase arrest, and significantly reduced cell proliferation in the hypoxia/reoxygenation group compared to the hypoxia group, which GA pretreatment mitigates. RNA-seq and bioinformatics analysis indicate GA's modulation of various signaling pathways, including IL-17, AMPK, MAPK, transient receptor potential channels, cAMP, and Rap1. In summary, GA pretreatment demonstrates potential in protecting parathyroid cells from IRI by influencing various genes and signaling pathways. These findings offer a promising therapeutic strategy for hypoparathyroidism treatment.

A delicate balance: the challenges of hypoparathyroidism

A 38-yr-old woman with chronic non-surgical hypoparathyroidism, managed elsewhere, presented to our practice with symptomatic hypocalcemia. At the age of 17, she began to suffer from muscle cramps, paresthesia, and ongoing diffuse pain. It took years before she was correctly diagnosed with hypoparathyroidism. Her symptoms were severe enough that she required emergency room visits several times a year. After she was properly diagnosed and started on calcium and calcitriol therapy, she continued to experience frequent episodes of severe hypocalcemia. She saw multiple healthcare providers who each introduced a new regimen. In addition, poor communication led to her discontinuing her medications altogether. As a result, her calcium levels remained consistently low, and she lost confidence in her prospect for better health. At the time of her visit to our clinic, she had discontinued calcitriol, was taking a large amount of oral calcium daily all at once, and had hypocalcemia. We addressed her concerns, and the challenges she faces with adherence to her medication regimen. We provided her with detailed information about the disease and the reasoning behind her treatment plan. Treatment was initiated with calcium carbonate 600 mg 3 times daily and calcitriol 0.5 mcg once daily. One week after treatment initiation, her test results showed improvement in her albumin-adjusted calcium, phosphorus, and 24-h urine calcium which were all within target range.

Associations between plasma metabolites and heavy metal exposure in residents of environmentally polluted areas

Heavy metals are commonly released into the environment through industrial processes such as mining and refining. The rapid industrialization that occurred in South Korea during the 1960s and 1970s contributed significantly to the economy of the country; however, the associated mining and refining led to considerable environmental pollution, and although mining is now in decline in South Korea, the detrimental effects on residents inhabiting the surrounding areas remain. The bioaccumulation of toxic heavy metals leads to metabolic alterations in human homeostasis, with disruptions in this balance leading to various health issues. This study used metabolomics to explore metabolomic alterations in the plasma samples of residents living in mining and refining areas. The results showed significant increases in metabolites involved in glycolysis and the surrounding metabolic pathways, such as glucose-6-phosphate, phosphoenolpyruvate, lactate, and inosine monophosphate, in those inhabiting polluted areas. An investigation of the associations between metabolites and blood clinical parameters through meet-in-the-middle analysis indicated that female residents were more affected by heavy metal exposure, resulting in more metabolomic alterations. For women, inhabiting the abandoned mine area, metabolites in the glycolysis and pentose phosphate pathways, such as ribose-5-phosphate and 3-phosphoglycerate, have shown a negative correlation with albumin and calcium. Finally, Mendelian randomization(MR) was used to determine the causal effects of these heavy metal exposure-related metabolites on heavy metal exposure-related clinical parameters. Metabolite biomarkers could provide insights into altered metabolic pathways related to exposure to toxic heavy metals and improve our understanding of the molecular mechanisms underlying the health effects of toxic heavy metal exposure.

Economic burden of patients with post-surgical chronic and transient hypoparathyroidism in the United States examined using insurance claims data

BACKGROUND

Hypoparathyroidism (HP) is a rare endocrine disease commonly caused by the removal or damage of parathyroid glands during surgery and resulting in transient (tHP) or chronic (cHP) disease. cHP is associated with multiple complications and comorbid conditions; however, the economic burden has not been well characterized. The objective of this study was to evaluate the healthcare resource utilization (HCRU) and costs associated with post-surgical cHP, using tHP as a reference.

METHODS

This analysis of a US claims database included patients with both an insurance claim for HP and thyroid/neck surgery between October 2014 and December 2019. cHP was defined as an HP claim ≥ 6 months following surgery and tHP was defined as only one HP claim < 6 months following surgery. The cHP index date was the first HP diagnosis claim following their qualifying surgery claim, whereas the tHP index date was the last HP diagnosis claim following the qualifying surgery claim. Patients were continuously enrolled at least 1 year pre- and post-index. Patients' demographic and clinical characteristics, all-cause HCRU, and costs were descriptively analyzed. Total all-cause costs were calculated as the sum of payments for hospitalizations, emergency department, office/clinic visits, and pharmacy.

RESULTS

A total of 1,406 cHP and 773 tHP patients met inclusion criteria. The average age (52.1 years cHP, 53.5 years tHP) and representation of females (83.2% cHP, 81.2% tHP) were similar for both groups. Neck dissection surgery was more prevalent in cHP patients (23.6%) than tHP patients (5.3%). During the 1-2 year follow-up period, cHP patients had a higher prevalence of inpatient admissions (17.4%), and emergency visits (26.0%) than the reference group -tHP patients (14.4% and 21.4% respectively). Among those with a hospitalization, the average number of hospitalizations was 1.5-fold higher for cHP patients. cHP patients also saw more specialists, including endocrinologists (28.7% cHP, 15.8% tHP), cardiologists (16.7% cHP, 9.7% tHP), and nephrologists (4.6% cHP, 3.3% tHP).

CONCLUSION

This study demonstrates the increased healthcare burden of cHP on the healthcare system in contrast to patients with tHP. Effective treatment options are needed to minimize the additional resources utilized by patients whose HP becomes chronic.

Treatment of Hypoparathyroidism by Re-Establishing the Effects of Parathyroid Hormone

The conventional treatment of hypoparathyroidism (HypoPT) includes active vitamin D and calcium. Despite normalization of calcium levels, the conventional treatment is associated with fluctuations in calcium levels, hypercalciuria, renal impairment, and decreased quality of life (QoL). Replacement therapy with parathyroid hormone (PTH)(1-84) is an option in some countries. However, convincing beneficial effects have not been demonstrated, which may be due to the short duration of action of this treatment. Recently, palopegteriparatide (also known as TransCon PTH) has been marketed in Europe and is expected also to be approved in other countries. Palopegteriparatide is a prodrug with sustained release of PTH(1-34) designed to provide stable physiological PTH levels for 24 hours/day. A phase 3 study demonstrated maintenance of normocalcemia in patients with chronic HypoPT, with no need for conventional therapy. Furthermore, this treatment lowers urinary calcium and improves QoL. Another long-acting PTH analog with effects on the parathyroid hormone receptor (eneboparatide) is currently being tested in a phase 3 trial. Furthermore, the treatment of autosomal dominant hypocalcemia type 1 with a calcilytic (encaleret) is also being tested. All in all, improved treatment options are on the way that will likely take the treatment of HypoPT to the next level.

Continuous Subcutaneous Delivery of rhPTH(1-84) and rhPTH(1-34) by Pump in Adults With Hypoparathyroidism

Context

Continuous subcutaneous infusion of recombinant parathyroid hormone (rhPTH) through a pump has been proposed as a therapeutic alternative for patients with chronic hypoparathyroidism who remain symptomatic or hypercalciuric on conventional treatment (calcium and active vitamin D) or daily injections of rhPTH(1-84) or rhPTH(1-34). However, the real-world evidence of the outcome of this novel therapy is limited.

Case Descriptions

We report the clinical and biochemical outcomes of 12 adults with hypoparathyroidism (11 women, age 30-70 years, and 1 man, age 30 years) from 3 different clinical sites in the United States who were transitioned from conventional therapy to daily injections of rhPTH(1-84) or rhPTH(1-34) and then switched to continuous administration of rhPTH(1-84)/rhPTH(1-34) via pump therapy. In most patients, mean serum calcium concentrations increased while on PTH pump therapy compared with both conventional therapy (in 11 patients) and single/multiple daily rhPTH injections (in 8 patients). Despite this, 10 patients had lower median 24-hour urinary calcium levels while on PTH pump therapy compared with prior therapy (mean ± SD difference: -130 ± 222 mg/24 hours). All patients reported a qualitative decrease in hypocalcemic symptoms while receiving pump therapy. Three patients had pod failure at least once, and 1 patient developed an infusion site reaction.

Conclusion

In this case series of 12 patients with chronic hypoparathyroidism treated with rhPTH(1-84)/rhPTH(1-34) administered via a pump, improvement in clinical and biochemical parameters were observed in the majority of the patients. Our observations indicate benefits of pump administration of rhPTH that warrant further investigation.

Transient binocular vision loss and pain insensitivity in Klippel-Feil syndrome: a case report

BACKGROUND

Klippel-Feil syndrome is a rare congenital bone disorder characterized by an abnormal fusion of two or more cervical spine vertebrae. Individuals with Klippel-Feil syndrome exhibit diverse clinical manifestations, including skeletal irregularities, visual and hearing impairments, orofacial anomalies, and anomalies in various internal organs, such as the heart, kidneys, genitourinary system, and nervous system.

CASE PRESENTATION

This case report describes a 12-year-old Pashtun female patient who presented with acute bilateral visual loss. The patient had Klippel-Feil syndrome, with the typical clinical triad symptoms of Klippel-Feil syndrome, along with Sprengel's deformity. She also exhibited generalized hypoalgesia, which had previously resulted in widespread burn-related injuries. Upon examination, bilateral optic disc swelling was observed, but intracranial pressure was found to be normal. Extensive investigations yielded normal results, except for hypocalcemia and low vitamin D levels, while parathyroid function remained within the normal range. Visual acuity improved following 2 months of calcium and vitamin D supplementation, suggesting that the visual loss and optic nerve swelling were attributed to hypocalcemia. Given the normal parathyroid function, it is possible that hypocalcemia resulted from low vitamin D levels, which can occur after severe burn scarring. Furthermore, the patient received a provisional diagnosis of congenital insensitivity to pain on the basis of the detailed medical history and the findings of severe and widespread loss of the ability to perceive painful stimuli, as well as impaired temperature sensation. However, due to limitations in genetic testing, confirmation of the congenital insensitivity to pain diagnosis could not be obtained.

CONCLUSION

This case highlights a rare presentation of transient binocular vision loss and pain insensitivity in a patient with Klippel-Feil syndrome, emphasizing the importance of considering unusual associations in symptom interpretation.

Insights and implications of sexual dimorphism in osteoporosis

Osteoporosis, a metabolic bone disease characterized by low bone mineral density and deterioration of bone microarchitecture, has led to a high risk of fatal osteoporotic fractures worldwide. Accumulating evidence has revealed that sexual dimorphism is a notable feature of osteoporosis, with sex-specific differences in epidemiology and pathogenesis. Specifically, females are more susceptible than males to osteoporosis, while males are more prone to disability or death from the disease. To date, sex chromosome abnormalities and steroid hormones have been proven to contribute greatly to sexual dimorphism in osteoporosis by regulating the functions of bone cells. Understanding the sex-specific differences in osteoporosis and its related complications is essential for improving treatment strategies tailored to women and men. This literature review focuses on the mechanisms underlying sexual dimorphism in osteoporosis, mainly in a population of aging patients, chronic glucocorticoid administration, and diabetes. Moreover, we highlight the implications of sexual dimorphism for developing therapeutics and preventive strategies and screening approaches tailored to women and men. Additionally, the challenges in translating bench research to bedside treatments and future directions to overcome these obstacles will be discussed.

Autofluorescence of Parathyroid Glands: A Review of Methods of Parathyroid Gland Identification and Parathyroid Vascular Assessment

Postoperative hypoparathyroidism may cause significant patient morbidity and even mortality. Emerging technologies centered on autofluorescent properties of parathyroid glands when exposed to near-infrared light hold promise to improve surgical parathyroid gland identification and preservation. Two systems (probe-based and camera-based) are commercially available currently; however, neither system alone provides indication of vascular viability or postoperative parathyroid gland function. The administration of indocyanine green, when combined with near-infrared fluorescence imaging, enables subjective assessment of parathyroid gland perfusion. Additional technologies to assess parathyroid gland perfusion are being developed. The impact of these nascent technologies on relevant clinical outcomes is an area of active investigation.

The fluorosis conundrum: bridging the gap between science and public health

Fluorosis, a chronic condition brought on by excessive fluoride ingestion which, has drawn much scientific attention and public health concern. It is a complex and multifaceted issue that affects millions of people worldwide. Despite decades of scientific research elucidating the causes, mechanisms, and prevention strategies for fluorosis, there remains a significant gap between scientific understanding and public health implementation. While the scientific community has made significant strides in understanding the etiology and prevention of fluorosis, effectively translating this knowledge into public health policies and practices remains challenging. This review explores the gap between scientific research on fluorosis and its practical implementation in public health initiatives. It suggests developing evidence-based guidelines for fluoride exposure and recommends comprehensive educational campaigns targeting the public and healthcare providers. Furthermore, it emphasizes the need for further research to fill the existing knowledge gaps and promote evidence-based decision-making. By fostering collaboration, communication, and evidence-based practices, policymakers, healthcare professionals, and the public can work together to implement preventive measures and mitigate the burden of fluorosis on affected communities. This review highlighted several vital strategies to bridge the gap between science and public health in the context of fluorosis. It emphasizes the importance of translating scientific evidence into actionable guidelines, raising public awareness about fluoride consumption, and promoting preventive measures at individual and community levels.

Hypoparathyroidism following total thyroidectomy: high rates at a low-volume, non-parathyroid institution

Background

Hypoparathyroidism following total thyroidectomy is globally the most common complication to thyroid surgery. The reported complication rates vary widely and might be highly dependent on the surgical experience. In this study we aimed to evaluate the rate of hypoparathyroidism following primary total thyroidectomy at a low-volume institution that only performs thyroid surgery and does not have any experience with parathyroid surgery.

Methods

Retrospective cohort study. All patients undergoing primary total thyroidectomy at the ENT-Department, Goedstrup Hospital, Denmark, over a 5-year period (2016-2020) were identified through the procedure codes for total thyroidectomy. Medical records, pathology reports, biochemical and medical histories were fully assessed for each patient. The primary endpoint was the rate of hypoparathyroidism- both immediate and permanent. Secondary outcomes were parathyroid gland identification rates, rates of parathyroid gland autotransplantation, and rates of inadvertent parathyroid gland excision.

Results

A total of 89 patients were included in the final analysis. A total of 33 patients (37.1%) experienced immediate hypoparathyroidism following surgery, while 30 patients (33.7%) still were on active vitamin D two months postoperatively. One year following surgery, 28 patients (31.5%) were still on active vitamin D and were considered as having permanent hypoparathyroidism. Sixty-one percent of the parathyroid glands were identified intraoperatively, and 19% of the patients experienced parathyroid autotransplantation. Inadvertent parathyroid gland excision occurred for 21% of the patients and was associated with a significantly increased risk of permanent hypoparathyroidism (RR = 2.99; 95% CI: 1.36 - 6.62, p = 0.005).

Conclusion

Both transient and permanent hypoparathyroidism following total thyroidectomy at a low-volume, non-parathyroid institution occurred with much higher frequencies than previously reported. The elevated rates were most likely due to the low-volume, non-parathyroid nature of the surgeons which in part was mirrored in low parathyroid gland identifications rates, and high rates of autotransplantation and inadvertent parathyroid gland excision.

GCM2 p.Tyr394Ser variant in Ashkenazi Israeli patients with suspected familial isolated hyperparathyroidism

Context

A germline mutation can be identified in up to 10% of patients with primary hyperparathyroidism (PHPT). In 2017, a high frequency of the GCM2 [(NM_ 004752.4) c.1181A> C; p.Tyr394Ser; rs142287570] variant was reported in PHPT Ashkenazi Jews (AJ).

Objective

To evaluate the presence of the GCM2 p.Tyr394Ser variant in Israeli patients addressed for genetic evaluation to characterize their phenotype and clinical management.

Method

Patients with PHPT who underwent addressed for genetic screening for suspected familial hypocalciuric hypercalcemia (FHH), a family history of isolated hyperparathyroidism (FIHP), or failed parathyroidectomy with persistent PHPT were recruited. Those with normal initial selected gene sequencing or hyperparathyroid genetic panel completed the GCM2 p.Tyr394Ser variant sequencing. The prevalence of this variant was evaluated using our local genomic database.

Results

A total of 42 single individuals from unrelated kindreds were evaluated. A disease-causing mutation was found in 11 (26.1%) patients: 10 were diagnosed with FHH (eight CASR and two AP2S1 mutations), and one patient had a CKN2B mutation. In 28 of the remaining patients, the GCM2 p.Tyr394Ser variant was positive in three (10.7%), and all were AJ. Within AJ (15/28, 53.5%), the rate of the p.Tyr394Ser variant was 3/15 (20%), and of those, two had a history of familial isolated hyperparathyroidism. Multi-glandular parathyroid adenoma/hyperplasia was also observed in two of these patients. No clinical or laboratory findings could discriminate patients with the GCM2 p.Tyr394Ser variant from those with FHH. Cinacalcet normalized the calcium levels in one patient. The prevalence of the GCM2 p.Tyr394Ser variant in 15,407 tests in our local genomic database was 0.98%.

Conclusion

In contrast to previous observations, the GCM2 p.Tyr394Ser variant-associated phenotype may be mild in AJ with FIHP, sometimes mimicking FHH. Because surgery may be curative, surgeons should be aware of the possibility of multiple gland diseases in these patients. The clinical spectrum and clinical utility of screening for this variant warrant further investigation.

Assessment of quality of life in patients with permanent hypoparathyroidism receiving conventional treatment

Introduction

Patients with permanent hypoparathyroidism suffer from multiple complaints and are exposed to long-term complications that might compromise their well-being. The aim of this study was to assess the quality of life (QoL) in patients with permanent hypoparathyroidism receiving conventional therapy and to determine the associated factors.

Methods

This was a cross-sectional matched case-control study including 53 patients with permanent hypoparathyroidism and 53 matched controls. Biochemical blood parameters (calcium, phosphate, albumin, magnesium, 25-hydroxy-vitamin D, creatinine, TSH, and PTH) and 24-hours calciuria were measured in patients with hypoparathyroidism. QoL was assessed in all participants using the Short Form 36 Health Survey (SF-36).

Results

The study included 53 patients (41 women and 12 men) with hypoparathyroidism receiving conventional therapy.Their mean age was 52.8 ± 16.5 years. In comparison with controls, patients with hypoparathyroidism had significantly lower scores in all eight domains of SF-36 (p < 10- 3). Patients with poor socioeconomic conditions had lower SF-36 scores than those with good conditions.The etiology of hypoparathyroidism, the disease duration, the control of the disease, and the body mass index did not significantly interfere with SF-36 scores. SF-36 total score was negatively correlated with age (r=-0.619, p < 10- 3) and symptoms of hypocalcemia (r=-0.284, p = 0.039), and positively correlated with creatinine clearance (r = 0.559, p < 10- 3), magnesium level (r = 0.345, p = 0.011), and 25 hydroxy-vitamin D level (r = 320, p = 0.021). No significant correlations were found between SF-36 scores and other biological parameters such as calcemia, phosphatemia, phosphocalcic product, PTH, TSH, and calciuria.

Conclusion

Patients with permanent hypoparathyroidism had impairment in their QoL. Age, socioeconomic conditions, renal function, magnesium level, and 25 hydroxy-vitamin D level may interfere in the decline of the QoL of these patients.

Renal complications in chronic hypoparathyroidism - a systematic cross-sectional assessment

Context

Although renal long-term complications are acknowledged in chronic hypoparathyroidism (HPT), standardized investigations are scarce.

Objective

To systematically investigate renal complications and their predictors in hypoparathyroid patients compared to matched individuals.

Design

Prospective observational study in 161 patients with chronic HPT.

Methods

Patients received renal ultrasound, clinical and laboratory assessments. An individual 1:3 matching with participants from the German population-based Study of Health in Pomerania was performed.

Results

Of 161 patients (92% postoperative HPT), prevalence of eGFR <60ml/min/1.73m2 was 21%, hypercalciuria 41%. Compared to healthy individuals, HPT patients had a significantly lower eGFR (74.2 vs. 95.7 ml/min/1.73m², p<0.01). Renal ultrasound revealed calcifications in 10% (nephrocalcinosis in 7% and calculi in 3%). Patients with renal calcifications had higher levels of 24-hour urine calcium excretion (8.34 vs. 5.08 mmol/d, p=0.02), spot urine calcium excretion (4.57 vs. 2.01 mmol/L, p=0.01) and urine calcium-to-creatinine ratio (0.25 vs. 0.16, p<0.01) than patients without calcifications. Albumin-corrected calcium, phosphate, calcium-phosphate product, 25-hydroxyvitamin D in serum, eGFR, daily calcium intake or disease duration were not significantly different between these two groups. Including patients receiving rhPTH therapy, a lower serum phosphate concentration (odds ratio 1.364 [95% confidence interval (CI) 1.049-1.776], p<0.05) and a longer disease duration of HPT (odds ratio 1.063 [95% CI 1.021-1.106], p<0.01) were significant predictors for renal calcifications. Excluding patients receiving rhPTH therapy, a higher 24-hour urine calcium excretion (odds ratio 1.215 [95% CI 1.058-1.396], p<0.01) was a significant predictor for renal calcifications but not serum magnesium or disease duration.

Conclusions

Prevalence of impaired renal function among patients with chronic HPT is increased and independent from visible renal calcifications. Depending on exclusion of patients with rhPTH therapy, regression analysis revealed disease duration and serum phosphate or disease duration and 24-hour urinary calcium excretion as predictors for renal calcifications.

Clin Trials Identifier

NCT05585593.

Fracture Risk in Patients with Hypoparathyroidism

PURPOSE OF REVIEW

To summarize the recently published scientific evidence on fracture risk in hypoparathyroidism.

RECENT FINDINGS

Hypoparathyroidism is characterized by a low bone turnover and a high bone mineral density. Data on fracture risk are sparse and due to the rarity of the disease, available studies have only been able to include relatively few patients. Risk of non-vertebral fractures does not seem to be affected to any major degree, although epidemiological studies suggest a decreased risk of fractures at the humerus in postsurgical hypoparathyroidism, whereas an increased risk of fractures at the upper arm has been shown in non-surgical hypoparathyroidism. Several, but not all, studies have also pointed towards an increased risk of vertebral fractures, especially in non-surgical hypoparathyroidism. Fractures at the appendicular skeleton do not seem to be of specific concern in hypoparathyroidism, but emerging data suggest an increased risk of vertebral fractures, which needs to be clarified further in upcoming studies.

Functional calcium-responsive parathyroid glands generated using single-step blastocyst complementation

Patients with permanent hypoparathyroidism require lifelong replacement therapy to avoid life-threatening complications, The benefits of conventional treatment are limited, however. Transplanting a functional parathyroid gland (PTG) would yield better results. Parathyroid gland cells generated from pluripotent stem cells in vitro to date cannot mimic the physiological responses to extracellular calcium that are essential for calcium homeostasis. We thus hypothesized that blastocyst complementation (BC) could be a better strategy for generating functional PTG cells and compensating loss of parathyroid function. We here describe generation of fully functional PTGs from mouse embryonic stem cells (mESCs) with single-step BC. Using CRISPR-Cas9 knockout of Glial cells missing2 (Gcm2), we efficiently produced aparathyroid embryos for BC. In these embryos, mESCs differentiated into endocrinologically mature PTGs that rescued Gcm2-/- mice from neonatal death. The mESC-derived PTGs responded to extracellular calcium, restoring calcium homeostasis on transplantation into mice surgically rendered hypoparathyroid. We also successfully generated functional interspecies PTGs in Gcm2-/- rat neonates, an accomplishment with potential for future human PTG therapy using xenogeneic animal BC. Our results demonstrate that BC can produce functional endocrine organs and constitute a concept in treatment of hypoparathyroidism.

Challenges in establishing animal models for studying osteoimmunology of hypoparathyroidism

Hypoparathyroidism is a relatively rare human and veterinary disease characterized by deficient or absent production of parathyroid hormone (PTH). PTH is known as a classical regulator of calcium and phosphorus homeostasis. Nevertheless, the hormone also appears to modulate immune functions. For example, increased CD4:CD8 T-cell ratios and elevated interleukin (IL)-6 and IL-17A levels were observed in patients with hyperparathyroidism, whereas gene expression of tumor necrosis factor-α (TNF-α) and granulocyte macrophage-colony stimulating factor (GM-CSF) was decreased in patients with chronic postsurgical hypoparathyroidism. Various immune cell populations are affected differently. So, there is a need for validated animal models for the further characterization of this disease for identifying targeted immune-modulatory therapies. In addition to genetically modified mouse models of hypoparathyroidism, there are surgical rodent models. Parathyroidectomy (PTX) can be well performed in rats-for pharmacological and associated osteoimmunological research and bone mechanical studies, a large animal model could be preferable, however. A major drawback for successfully performing total PTX in large animal species (pigs and sheep) is the presence of accessory glands, thus demanding to develop new approaches for real-time detection of all parathyroid tissues.

A Case of Hypoparathyroidism in Type 1 Diabetes Mellitus

This case report discusses a 13-year-old female with a known history of type 1 diabetes mellitus presenting with pain in bilateral lower limbs, generalized weakness, and fatigue. After laboratory examinations, hypoparathyroidism was diagnosed based on low serum calcium, elevated serum phosphorous, and lower serum intact parathyroid hormone (PTH) levels. Treatment with calcium and vitamin D supplements led to a reduction in the patient's symptoms. The report provides an overview of the pathophysiology of hypoparathyroidism, its various etiologies, and clinical manifestations. The report emphasizes the importance of considering hypoparathyroidism as a differential diagnosis in patients with unexplained neuromuscular symptoms, even without a known thyroid disease or previous thyroid surgery.

Severe hypocalcaemia episodes in a patient of primary hypoparathyroidism precipitated by underlying stress due to haemophagocytic lymphohistiocytosis (HLH) secondary to pulmonary tuberculosis

A man in his 20s who had previously experienced multiple episodes of transient loss of consciousness, majorly attributable to the seizures, presented with a 1-month history of increased seizure frequency, high-grade fever and weight loss. Clinically, he had postural instability, bradykinesia and symmetrical cogwheel rigidity. His investigations revealed hypocalcaemia, hyperphosphataemia, inappropriately normal intact parathyroid hormone, metabolic alkalosis, normomagnesemic magnesium depletion, and increased plasma renin activity and serum aldosterone concentration. CT scan of the brain revealed symmetrical calcification of the basal ganglia. The patient had primary hypoparathyroidism (HP). A similar presentation of his brother indicated a genetic cause, most likely autosomal dominant hypocalcaemia with Bartter's syndrome type 5. The patient's fever was caused by underlying haemophagocytic lymphohistiocytosis secondary to pulmonary tuberculosis, which triggered acute episodes of hypocalcaemia. This case represents a complex interplay of a multifaceted relationship between primary HP, vitamin D deficiency and an acute stressor.

Evaluation of an early detection protocol, intensive treatment and control of post-surgical hypoparathyroidism in the first month after total thyroidectomy

BACKGROUND AND OBJECTIVE

Hypoparathyroidism is the most common complication of total thyroidectomy and usually requires monitoring of calcaemia, whereby it is one of the factors that most contributes to hospital stay. The objective of the study is to evaluate the clinical usefulness of the application of our protocol for early detection, intensive treatment and control of hypoparathyroidism in the first month after thyroidectomy.

PATIENTS AND METHOD

Retrospective observational cross-sectional study of 79 patients who underwent total thyroidectomy in whom parathormone (PTH) and calcemia determinations were performed at 6-8 h and 18-24 h post-surgery. When the PTH value was lower than inferior limit of the reference (15 pg/ml), oral treatment was started with 1000 mg of calcium and 0.25 μg of calcitriol every 8 h followed by calcemia controls.

RESULTS

Twenty-six cases (32.9%) of normocalcemic hypoparathyroidism were detected in whom treatment prevented their progression to hypocalcaemia, except for 3 cases that had an episode of mild asymptomatic hypocalcaemia. There were no cases of moderate/severe hypocalcaemia and only one case of asymptomatic mild hypercalcaemia. There were no readmissions due to calcium abnormalities. No case with PTH > 15 pg/ml had hypocalcaemia. The protocol allowed a hospital stay of 24 h. The prevalence of permanent hypoparathyroidism was 5.1%.

CONCLUSIONS

The application of our protocol during the first month after thyroidectomy is very useful because it avoids the appearance of moderate/severe hypocalcaemia and hypercalcaemia, allows a short hospital stay and is associated with a low prevalence of permanent hypoparathyroidism.

Educational Review: Intraoperative Parathyroid Fluorescence Detection Technology in Thyroid and Parathyroid Surgery

BACKGROUND

Accurate parathyroid gland (PG) identification is a critical yet challenging component of cervical endocrine procedures. PGs possess strong near-infrared autofluorescence (NIRAF) compared with other tissues in the neck. This property has been harnessed by image- and probe-based near-infrared fluorescence detection systems, which have gained increasing popularity in clinical use for their ability to accurately aid in PG identification in a rapid, noninvasive, and cost-effective manner. All NIRAF technologies, however, cannot differentiate viable from devascularized PGs without the use of contrast enhancement. Here, we aim to provide an overview of the rapid evolution of these technologies and update the surgery community on the most recent advancements in the field.

METHODS

A PubMed literature review was performed using the key terms "parathyroid," "near-infrared," and "fluorescence." Recommendations regarding the use of these technologies in clinical practice were developed on the basis of the reviewed literature and in conjunction with expert surgeons' opinions.

RESULTS

The use of near-infrared fluorescence detection can be broadly categorized as (1) using parathyroid NIRAF to identify both healthy and diseased PGs, and (2) using contrast-enhanced (i.e., indocyanine green) near-infrared fluorescence to evaluate PG perfusion and viability. Each of these approaches possess unique advantages and disadvantages, and clinical trials are ongoing to better define their utility.

CONCLUSIONS

Near-infrared fluorescence detection offers the opportunity to improve our collective ability to identify and preserve PGs intraoperatively. While additional work is needed to propel this technology further, we hope this review will be valuable to the practicing surgeon.

Transient Loss of Consciousness Associated With Severe Hypocalcemia and QT Prolongation Due to Primary Hypoparathyroidism in an Adolescent Girl

As hypocalcemia is uncommon, serum calcium levels are not routinely measured in many emergency medicine clinics. We report a case of an adolescent girl with a transient loss of consciousness due to hypocalcemia. A 13-year-old healthy girl had a syncopal episode complicated with numbness in the extremities. On admission, she was fully conscious, but hypocalcemia and QT prolongation were noted. After careful consideration of the possible etiologies, the patient was diagnosed with acquired QT prolongation due to primary hypoparathyroidism. The patient's serum calcium levels were controlled by activated vitamin D and calcium supplementation. Primary hypoparathyroidism-associated hypocalcemia can cause QT prolongation and neurological complications, even in previously healthy adolescents.

Efficacy and Safety of Parathyroid Hormone Replacement With TransCon PTH in Hypoparathyroidism: 26-Week Results From the Phase 3 PaTHway Trial

Conventional therapy for hypoparathyroidism consisting of active vitamin D and calcium aims to alleviate hypocalcemia but fails to restore normal parathyroid hormone (PTH) physiology. PTH replacement therapy is the ideal physiologic treatment for hypoparathyroidism. The double-blind, placebo-controlled, 26-week, phase 3 PaTHway trial assessed the efficacy and safety of PTH replacement therapy for hypoparathyroidism individuals with the investigational drug TransCon PTH (palopegteriparatide). Participants (n = 84) were randomized 3:1 to once-daily TransCon PTH (initially 18 μg/d) or placebo, both co-administered with conventional therapy. The study drug and conventional therapy were titrated according to a dosing algorithm guided by serum calcium. The composite primary efficacy endpoint was the proportion of participants at week 26 who achieved normal albumin-adjusted serum calcium levels (8.3-10.6 mg/dL), independence from conventional therapy (requiring no active vitamin D and ≤600 mg/d of calcium), and no increase in study drug over 4 weeks before week 26. Other outcomes of interest included health-related quality of life measured by the 36-Item Short Form Survey (SF-36), hypoparathyroidism-related symptoms, functioning, and well-being measured by the Hypoparathyroidism Patient Experience Scale (HPES), and urinary calcium excretion. At week 26, 79% (48/61) of participants treated with TransCon PTH versus 5% (1/21) wiplacebo met the composite primary efficacy endpoint (p < 0.0001). TransCon PTH treatment demonstrated a significant improvement in all key secondary endpoint HPES domain scores (all p < 0.01) and the SF-36 Physical Functioning subscale score (p = 0.0347) compared with placebo. Additionally, 93% (57/61) of participants treated with TransCon PTH achieved independence from conventional therapy. TransCon PTH treatment normalized mean 24-hour urine calcium. Overall, 82% (50/61) treated with TransCon PTH and 100% (21/21) wiplacebo experienced adverse events; most were mild (46%) or moderate (46%). No study drug-related withdrawals occurred. In conclusion, TransCon PTH maintained normocalcemia while permitting independence from conventional therapy and was well-tolerated in individuals with hypoparathyroidism. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Parameters of Vitamin D Metabolism in Patients with Hypoparathyroidism

Only a few studies evaluating the metabolism of vitamin D in patients with hypoparathyroidism (HypoPT) have been performed thus far, and, in particular, they mainly investigated the process of vitamin D activation (specifically, 1α-hydroxylation). This study, therefore, aimed to evaluate the extended spectrum of vitamin D metabolites in patients with HypoPT compared to healthy individuals. We examined 38 adult patients with chronic HypoPT in comparison to 38 healthy adults. The assessment included biochemical parameters (total calcium, albumin, phosphorus, creatinine, and magnesium), parathyroid hormone (PTH), and vitamin D metabolites (25(OH)D3, 25(OH)D2, 1,25(OH)2D3, 3-epi-25(OH)D3, and 24,25(OH)2D3) in serum. Our data show that an adequate level of 25(OH)D3 (median 35.3 (29.6; 42.0) ng/mL) is achieved with standard doses of cholecalciferol (median 2000 (2000; 2500) IU per day) in HypoPT patients. They also presented with supraphysiological levels of 1,25(OH)2D3 (median 71 (47; 96) vs. 40 (34; 59) pg/mL, p < 0.001) and the increased production of inactive metabolite (median 24,25(OH)2D3 3.8 (3.0; 5.1) vs. 1.9 (1.3; 2.7) ng/mL, p < 0.001; median 25(OH)D3/24,25(OH)2D3 ratio 8.9 (7.6; 11.1) vs. 13.5 (11.1; 17.0), p < 0.001) as compared to the control group. This might be a consequence of the therapy received (treatment with activated vitamin D) and the pathophysiology of the disease (lack of PTH). The abnormality of vitamin D metabolism does not seem to interfere with the achievement of hypoparathyroidism compensation.

Management of Hypoparathyroidism

Hypoparathyroidism (HypoPT) is a rare disorder characterized by hypocalcemia in the presence of a low or inappropriately normal parathyroid hormone level. HypoPT is most commonly seen after neck surgery, which accounts for approximately 75% of cases, whereas approximately 25% have HypoPT due to nonsurgical causes. In both groups of patients, conventional therapy includes calcium and active vitamin D analogue therapy aiming to maintain serum calcium concentration in the low normal or just below the normal reference range and normalize serum phosphorus, magnesium concentrations, and urine calcium levels. The limitations of conventional therapy include wide fluctuations in serum calcium, high pill burden, poor quality of life, and renal complications. Parathyroid hormone (PTH) replacement therapy may improve the biochemical profile in those in whom conventional therapy proves unsatisfactory. Based on a systematic review and meta-analysis of the literature, the panel made a graded recommendation suggesting conventional therapy as first line therapy rather than administration of PTH (weak recommendation, low quality evidence). When conventional therapy is deemed unsatisfactory, the panel considers use of PTH. Because pregnancy and lactation are associated with changes in calcium homeostasis, close monitoring is required during these periods with appropriate adjustment of calcium and active vitamin D analogue therapy to ensure that serum calcium remains in the mid to low normal reference range in order to avoid maternal and fetal complications. Emerging therapies include molecules with prolonged PTH action as well as different mechanisms of action that may significantly enhance drug efficacy and safety. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Complications, Symptoms, Presurgical Predictors in Patients With Chronic Hypoparathyroidism: A Systematic Review

The complications and symptoms of hypoparathyroidism remain incompletely defined. Measuring serum parathyroid hormone (PTH) and calcium levels early after total thyroidectomy may predict the development of chronic hypoparathyroidism. The study aimed (i) to identify symptoms and complications associated with chronic hypoparathyroidism and determine the prevalence of those symptoms and complications (Part I), and (ii) to examine the utility of early postoperative measurements of PTH and calcium in predicting chronic hypoparathyroidism (Part II). We searched Medline, Medline In-Process, EMBASE, and Cochrane CENTRAL to identify complications and symptoms associated with chronic hypoparathyroidism. We used two predefined criteria (at least three studies reported the complication and symptom and had statistically significantly greater pooled relative estimates). To estimate prevalence, we used the median and interquartile range (IQR) of the studies reporting complications and symptoms. For testing the predictive values of early postoperative measurements of PTH and calcium, we used a bivariate model to perform diagnostic test meta-analysis. In Part I, the 93 eligible studies enrolled a total of 18,973 patients and reported on 170 complications and symptoms. We identified nine most common complications or symptoms probably associated with chronic hypoparathyroidism. The complications or symptoms and the prevalence are as follows: nephrocalcinosis/nephrolithiasis (median prevalence among all studies 15%), renal insufficiency (12%), cataract (17%), seizures (11%), arrhythmia (7%), ischemic heart disease (7%), depression (9%), infection (11%), and all-cause mortality (6%). In Part II, 18 studies with 4325 patients proved eligible. For PTH measurement, regarding the posttest probability, PTH values above 10 pg/mL 12-24 hours postsurgery virtually exclude chronic hypoparathyroidism irrespective of pretest probability (100%). When PTH values are below 10 pg/mL, posttest probabilities range from 3% to 64%. Nine complications and symptoms are probably associated with chronic hypoparathyroidism. A PTH value above a threshold of 10 pg/mL 12-24 hours after total thyroidectomy is a strong predictor that the patients will not develop chronic hypoparathyroidism. Patients with PTH values below the threshold need careful monitoring as some will develop chronic hypoparathyroidism. © 2022 American Society for Bone and Mineral Research (ASBMR).

Epidemiology and Financial Burden of Adult Chronic Hypoparathyroidism

Chronic hypoparathyroidism is characterized by low serum calcium, increased serum phosphorus, and inappropriately low or decreased serum parathyroid hormone. This rare disorder is associated with a variety of complications. The prevalence, incidence, mortality, financial burden, and epidemiology of complications of this disorder are not well understood. This narrative review summarizes current information on the epidemiology and complications of chronic hypoparathyroidism. The reported prevalence of chronic hypoparathyroidism ranges from 6.4-37/100,000, and the incidence is reported to be 0.8-2.3/100,000/year. Mortality is not increased in studies from Denmark or South Korea but was increased in studies from Scotland and Sweden. The financial burden of this disorder is substantial because of increased health care resource utilization in two studies but not well quantitated. Recognized complications include hypercalciuria, nephrocalcinosis, kidney stones, and chronic kidney disease; low bone turnover and possibly upper extremity fractures; cardiac and vascular calcifications; basal ganglia calcifications, cataracts, infections, neuropsychiatric complications, and difficulties with pregnancy. This review concludes that chronic hypoparathyroidism is a rare disorder associated with significant morbidity that may not increase overall mortality but is associated with a substantial financial burden. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Evaluation and Management of Hypoparathyroidism Summary Statement and Guidelines from the Second International Workshop

This clinical practice guideline addresses the prevention, diagnosis, and management of hypoparathyroidism (HypoPT) and provides evidence-based recommendations. The HypoPT task forces included four teams with a total of 50 international experts including representatives from the sponsoring societies. A methodologist (GG) and his team supported the taskforces and conducted the systematic reviews. A formal process following the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology and the systematic reviews provided the structure for seven of the guideline recommendations. The task force used a less structured approach based on narrative reviews for 20 non-GRADEd recommendations. Clinicians may consider postsurgical HypoPT permanent if it persists for >12 months after surgery. To predict which patients will not develop permanent postsurgical HypoPT, we recommend evaluating serum PTH within 12 to 24 hours post total thyroidectomy (strong recommendation, moderate quality evidence). PTH > 10 pg/mL (1.05 pmol/L) virtually excludes long-term HypoPT. In individuals with nonsurgical HypoPT, genetic testing may be helpful in the presence of a positive family history of nonsurgical HypoPT, in the presence of syndromic features, or in individuals younger than 40 years. HypoPT can be associated with complications, including nephrocalcinosis, nephrolithiasis, renal insufficiency, cataracts, seizures, cardiac arrhythmias, ischemic heart disease, depression, and an increased risk of infection. Minimizing complications of HypoPT requires careful evaluation and close monitoring of laboratory indices. In patients with chronic HypoPT, the panel suggests conventional therapy with calcium and active vitamin D metabolites as first-line therapy (weak recommendation, low-quality evidence). When conventional therapy is deemed unsatisfactory, the panel considers the use of PTH. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Kinetic and Thermodynamic Insights into Agonist Interactions with the Parathyroid Hormone Receptor-1 from a New NanoBRET Assay

Polypeptides that activate the parathyroid hormone receptor-1 (PTHR1) are important in human physiology and medicine. Most previous studies of peptide binding to this receptor have involved the displacement of a radiolabeled ligand. We report a new assay format based on bioluminescence resonance energy transfer (BRET). Fusion of a NanoLuc luciferase (nLuc) unit to the N-terminus of the PTHR1 allows the direct detection of binding by an agonist peptide bearing a tetramethylrhodamine (TMR) unit. Affinity measurements from the BRET assay align well with results previously obtained via radioligand displacement. The BRET assay offers substantial operational benefits relative to affinity measurements involving radioactive compounds. The convenience of the new assay allowed us to explore several questions raised by earlier reports. For example, we show that although the first two residues of PTH(1-34) (the drug teriparatide) are critical for PTHR1 activation, these two residues contribute little or nothing to affinity. Comparisons among the well-studied agonists PTH(1-34), PTHrP(1-34), and "long-acting PTH" (LA-PTH) reveal that the high affinity of LA-PTH arises largely from a diminished rate constant for dissociation relative to the other two. A D-peptide recently reported to be comparable to PTH(1-34) as an agonist of the PTHR1 was found not to bind detectably to the receptor and to be a very weak agonist.

Skeletal and nonskeletal consequences of hypoparathyroidism

Hypoparathyroidism, despite the conventional therapy with calcium and active vitamin D, can lead to skeletal and nonskeletal abnormalities. Chronic hypoparathyroidism is associated with a significant reduction in bone remodeling, increases in areal and volumetric bone density, and improvement in trabecular microarchitecture and in trabecular bone score. Regardless of these advantages in bone mass and microarchitecture, recent data suggest an increased vertebral fracture risk in patients with nonsurgical hypoparathyroidism. Moreover, chronic hypoparathyroidism can lead to abnormalities in multiple organ systems, including the neurological, cardiovascular, renal, neuropsychiatric, ocular, and immune systems. Nephrocalcinosis, nephrolithiasis, and renal insufficiency, as well as decreased quality of life and cataracts, are common in patients with hypoparathyroidism. An increased incidence of hospitalization due to infections and a greater risk of cardiovascular diseases are observed in patients with hypoparathyroidism, particularly in those with nonsurgical disease. All these abnormalities may be because of the disease itself or complications of therapy. We herein reviewed the skeletal and nonskeletal consequences of hypoparathyroidism in patients conventionally managed with calcium and active vitamin D.

Bioactive, full-length parathyroid hormone delivered using an adeno-associated viral vector

Delivering the parathyroid hormone (PTH) gene has been attempted preclinically in a handful of studies, but delivering full-length PTH (1-84) using adeno-associated viral (AAV) vectors has not. Given the difficulty in achieving therapeutic levels of secreted proteins using gene therapy, this study seeks to determine the feasibility of doing so with PTH. An AAV vector was used to deliver human PTH driven by a strong promoter. We demonstrate the ability to secrete full-length PTH from various cell types in vitro. PTH secretion from hepatocytes was measured over time and a fluorescent marker was used to compare the secretion rate of PTH in various cell types. Potency was measured by the ability of PTH to act on the PTH receptors of osteosarcoma cells and induced proliferation. PTH showed potency in vitro by inducing proliferation in two osteosarcoma cell lines. In vivo, AAV was administered systemically in immunocompromised mice which received xenografts of osteosarcoma cells. Animals that received the highest dose of AAV-PTH had higher liver and plasma concentrations of PTH. All dosing groups achieved measurable plasma concentrations of human PTH that were above the normal range. The high-dose group also had significantly larger tumors compared to control groups on the final day of the study. The tumors also showed dose-dependent differences in morphology. When looking at endocrine signaling and endogenous bone turnover, we observed a significant difference in tibial growth plate width in animals that received the high-dose AAV as well as dose-dependent changes in blood biomarkers related to PTH. This proof-of-concept study shows promise for further exploration of an AAV gene therapy to deliver full-length PTH for hypoparathyroidism. Additional investigation will determine efficacy in a disease model, but data shown establish bioactivity in well-established models of osteosarcoma.