Hyperparathyroid and hypoparathyroid disorders

Should all patients with hyperparathyroidism be screened for a CDC73 mutation?

Primary hyperparathyroidism (PH) is a common endocrine abnormality and may occur as part of a genetic syndrome. Inactivating mutations of the tumour suppressor gene CDC73 have been identified as accounting for a large percentage of hyperparathyroidism-jaw tumour syndrome (HPT-JT) cases and to a lesser degree account for familial isolated hyperparathyroidism (FIHP) cases. Reports of CDC73 whole gene deletions are exceedingly rare. We report the case of a 39 year-old woman with PH secondary to a parathyroid adenoma associated with a large chromosomal deletion (2.5 Mb) encompassing the entire CDC73 gene detected years after parathyroidectomy. This case highlights the necessity to screen young patients with hyperparathyroidism for an underlying genetic aetiology. It also demonstrates that molecular testing for this disorder should contain techniques that can detect large deletions.

Hyperparathyroidism

Primary hyperparathyroidism is a common endocrine disorder of calcium metabolism characterised by hypercalcaemia and elevated or inappropriately normal concentrations of parathyroid hormone. Almost always, primary hyperparathyroidism is due to a benign overgrowth of parathyroid tissue either as a single gland (80% of cases) or as a multiple gland disorder (15-20% of cases). Primary hyperparathyroidism is generally discovered when asymptomatic but the disease always has the potential to become symptomatic, resulting in bone loss and kidney stones. In countries where biochemical screening tests are not common, symptomatic primary hyperparathyroidism tends to predominate. Another variant of primary hyperparathyroidism has been described in which the serum calcium concentration is within normal range but parathyroid hormone is elevated in the absence of any obvious cause. Primary hyperparathyroidism can be cured by removal of the parathyroid gland or glands but identification of patients who are best advised to have surgery requires consideration of the guidelines that are regularly updated. Recommendations for patients who do not undergo parathyroid surgery include monitoring of serum calcium concentrations and bone density.

Effect of Prophylactic Calcitriol Administration on Serum Ionized Calcium Concentrations after Parathyroidectomy: 78 Cases (2005-2015)

Background

Prophylactic administration of calcitriol has been suggested to mitigate the risk of hypocalcemia after parathyroidectomy. The effect of calcitriol on postoperative serum ionized calcium concentrations has not been evaluated in dogs after parathyroidectomy.

Hypothesis/Objectives

To determine the effect of prophylactic calcitriol administration on postoperative serum ionized calcium (iCa) concentrations in dogs with primary hyperthyroidism (PHPTH) treated by parathyroidectomy.

Animals

Seventy‐eight dogs with primary hyperparathyroidism treated surgically.

Methods

Multi‐institutional retrospective case study. Medical records from 2005 to 2015 were evaluated. Dogs were included if they had a diagnosis of PHPTH and had surgery to remove parathyroid tissue. Serum iCa concentrations were monitored for a minimum of 2 days postoperatively. Two study groups were evaluated: calcitriol administration and no calcitriol administration.

Results

Serial postoperative iCa concentrations measured at 12‐hour time intervals for 2 days postoperatively were positively associated with preoperative iCa concentrations. This association was evident at each time interval, and the effect of preoperative iCa concentrations on postoperative iCa concentrations decreased as time elapsed (12 hours, P < 0.0001; 24 hours, P < 0.0001; 36 hours, P < 0.04; and 48 hours, P = 0.01). Prophylactic calcitriol administration was not found to be significantly associated with postoperative iCa concentrations or its rate of decrease after parathyroidectomy.

Conclusion and Clinical Importance

We found no protective value in administering calcitriol prophylactically to prevent hypocalcemia in the immediate postoperative period (48 hours) after parathyroidectomy. Preoperative iCa concentrations had a significant positive association with postoperative iCa concentrations throughout the monitoring period.

Secondary hyperparathyroidism causing increased jaw bone density and mandibular pain: a case report

We present the case of a 32-year-old male patient complaining of recurrent mandibular pain for 3.5 years. Panoramic radiography indicated increased cortical density of the mandibular lower border. Scintigraphy and single-photon emission computed tomography revealed metabolic hyperactivity in that region without pathologic lymph nodes. A bone biopsy specimen of the mandibular lower border did not have inflammation or cytologic atypia. Endocrinologic investigation confirmed secondary hyperparathyroidism as a result of hypovitaminosis D. Several weeks after starting therapy with oral vitamin D supplements, the symptoms completely disappeared. Increased cortical density is a rare manifestation of secondary hyperparathyroidism, which normally causes the lamina dura to vanish and produces a ground-glass appearance as a result of blurring of the trabecular bone pattern. Because focal hyperostosis can have multiple benign or malignant causes, radiologic examination of the jaw bones is indispensable for evaluating orofacial pain. Increased cortical density may be caused by metabolic diseases, requiring further investigations, including biopsy and blood analysis.

Molecular genetics of syndromic and non-syndromic forms of parathyroid carcinoma

Parathyroid carcinoma (PC) may occur as part of a complex hereditary syndrome or an isolated (i.e., non-syndromic) non-hereditary (i.e., sporadic) endocrinopathy. Studies of hereditary and syndromic forms of PC, which include the hyperparathyroidism-jaw tumor syndrome (HPT-JT), multiple endocrine neoplasia types 1 and 2 (MEN1 and MEN2), and familial isolated primary hyperparathyroidism (FIHP), have revealed some genetic mechanisms underlying PC. Thus, cell division cycle 73 (CDC73) germline mutations cause HPT-JT, and CDC73 mutations occur in 70% of sporadic PC, but in only ∼2% of parathyroid adenomas. Moreover, CDC73 germline mutations occur in 20%-40% of patients with sporadic PC and may reveal unrecognized HPT-JT. This indicates that CDC73 mutations are major driver mutations in the etiology of PCs. However, there is no genotype-phenotype correlation and some CDC73 mutations (e.g., c.679_680insAG) have been reported in patients with sporadic PC, HPT-JT, or FIHP. Other genes involved in sporadic PC include germline MEN1 and rearranged during transfection (RET) mutations and somatic alterations of the retinoblastoma 1 (RB1) and tumor protein P53 (TP53) genes, as well as epigenetic modifications including DNA methylation and histone modifications, and microRNA misregulation. This review summarizes the genetics and epigenetics of the familial syndromic and non-syndromic (sporadic) forms of PC.

Value of preoperative ultrasound-guided fine-needle aspiration for localization in Tc-99m MIBI-negative primary hyperparathyroidism patients

To evaluate the value of preoperative ultrasound-guided fine-needle aspiration (UG-FNA) of ultrasound-detected suspicious parathyroid nodules for localization in Tc-99m MIBI-negative primary hyperparathyroidism patients.From May 2008 to December 2016, Tc-99m MIBI-negative primary hyperparathyroidism patients with ultrasound-detected suspicious cervical nodules underwent UG-FNA. The sample obtained from the solid component of the nodule was subjected to cytological evaluation and immunohistochemical staining. The sample obtained from the cystic component of the nodule or solid nodules was subjected to parathyroid hormone determination. After aspiration, the nodules underwent surgical resection or follow-up.Fifteen nodules (5 cystic, 5 cystic and solid, and 5 solid) from 15 patients were subjected to UG-FNA. Aspirate samples were obtained from 12 of the nodules, and the parathyroid hormone (PTH) levels of these samples were markedly elevated (range: 302- >2500 pg/mL). The samples obtained from the solid components of the 4 cystic and solid and 4 solid nodules were subjected to cytological evaluation, and parathyroid cells were identified in 5 of them. Of these 5 cases, 4 were subjected to immunohistochemical staining, which revealed PTH positivity in the cell block. The UG-FNA results suggested that the suspicious nodules were all parathyroid lesions. The surgical pathology results of 13 cases confirmed the UG-FNA results; the follow-up of 2 cases did not reveal any significant change.The cytological evaluation, immunohistochemical staining, and aspirate fluid PTH determination of UG-FNA were helpful for preoperative localization in Tc-99m MIBI-negative primary hyperparathyroidism patients with ultrasound-detected suspicious parathyroid nodules and can be applied selectively or in combination. Aspirate sample PTH determination should be preferred for nodules with cystic components. Further prospective study with large population is needed to confirm our conclusions.

Echocardiogram changes following parathyroidectomy for primary hyperparathyroidism: A systematic review and meta-analysis

The aim of the study is to systematically review the evidence on post parathyroidectomy (PTX) changes as measured by echocardiogram (ECHO) in patients with primary hyperparathyroidism (PHPT).PHPT may increase risk of cardiovascular morbidity/mortality. Conclusions of studies assessing ECHO changes, pre versus post PTX, are inconsistent.A systematic literature search was conducted to locate published and unpublished studies. Randomized control trials, nonrandomized control trials, and observational studies were included. Variables were reported as means and standard deviations. An inverse variance statistical method, with random-effects analysis model, was applied to continuous data. The effect measure was standardized mean difference, confidence interval of 95%. Primary outcome measure was left ventricular ejection fraction (LVEF). Secondary outcome measures were left ventricular mass index (LVMI), peak early over peak late diastolic velocity ratio (E/A ratio), isovolumetric relaxation time (IVRT), intraventricular septal thickness (IVST), and posterior wall thickness (PWT).Fourteen studies were included. Follow-up time ranged 3 to 67 months. No significant differences (P > .05) in primary outcome measure LVEF (SMD = -0.03, CI = -0.24, 0.19), or secondary outcome measures E/A Ratio (SMD = -0.05, CI = -0.24, 0.14), IVST (SMD = 0, CI = 0.31, 0.32), PWT (SMD = 0.01, CI = -0.38, 0.39), LVMI (SMD = -0.18, CI = -0.74, 0.38), and IVRT (SMD = -0.84, CI = -1.83, 0.14) were observed.There was no significant difference in LVEF pre to post PTX. Due to heterogeneity of current literature, we were unable to determine if other outcome measures of cardiac function are affected after PTX in patients with PHPT. We recommend a randomized control trial be conducted to make concrete conclusions.

Hyperparathyroidism-Jaw Tumor Syndrome Associated With Large-Scale 1q31 Deletion

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare autosomal dominant cause of familial hyperparathyroidism associated with benign, ossifying fibromas of the maxillofacial bones and increased risk of parathyroid carcinoma. The putative tumor suppressor gene CDC73 has been implicated in the syndrome, with a multitude of inactivating mutations identified; however, HPT-JT due to large-scale deletion of the chromosomal region containing the gene is exceedingly rare, and the clinical significance of this variant remains unclear. We report the case of a 32-year-old woman with a history of mandibular ossifying fibroma who presented with primary hyperparathyroidism and was found to harbor a large-scale, germline deletion on chromosome 1q31, including the CDC73 locus. HPT-JT is associated with loss of function of the putative tumor suppressor gene CDC73. Over 100 mutations and small insertions/deletions have been identified within the gene, the majority of which result in premature truncation of the parafibromin protein product. We report a case of HPT-JT associated with a large chromosomal deletion (4.1 Mb) encompassing the CDC73 gene locus. In the future, molecular testing in this autosomal dominant disorder should use techniques that allow for the detection of large-scale deletions in addition to the more commonly observed mutations and smaller-scale copy number alterations. Further investigation is needed to determine whether HPT-JT associated with a large-scale deletion carries increased risk of malignancy relative to the more common truncating mutations and what the implications are for genetic counseling.

Acute symptomatic hypocalcemia from immune checkpoint therapy-induced hypoparathyroidism

BACKGROUND

Ipilimumab (a monoclonal antibody against CTLA-4) and nivolumab (a humanized antibody against PD-1) target these immune checkpoint pathways and are used for treatment of melanoma and an increasing number of other cancers. However, they may cause immune-related adverse effects (IRAEs). Although many endocrinopathies are known to be IRAEs, primary hypoparathyroidism with severe hypocalcemia has never been reported. This is the first case of hypoparathyroidism as an IRAE presenting to an Emergency Department with acute hypocalcemia.

CASE DESCRIPTION

A 73-year-old man with metastatic melanoma presented to the Emergency Department for the chief complaints of imbalance, general muscle weakness, abdominal pain and tingling in extremities. He had wide spread metastasis, and begun immunotherapy with concurrent ipilimumab and nivolumab 1.5months ago. At presentation, he had ataxia, paresthesia in the hands and feet, and abdominal cramping. Magnetic resonance imaging of the brain was unremarkable. He was found to be hypocalcemic with undetectable plasma parathyroid hormone. He was admitted for treatment of symptomatic hypocalcemia and was diagnosed with primary hypoparathyroidism. Shortly afterwards, he had thyrotoxicosis manifesting as tachycardia and anxiety, followed by development of primary hypothyroidism. At 4months after the Emergency Department visit, his parathyroid function and thyroid function had not recovered, and required continued thyroid hormone replacement and calcium and vitamin D treatment for hypocalcemia.

CONCLUSIONS

Primary hypoparathyroidism caused by ipilimumab and nivolumab may acute manifest with severe symptomatic hypocalcemia. Emergency care providers should be aware of hypoparathyroidism as a new IRAE in this new era of immuno-oncology.

The Essentials of Parathyroid Hormone Venous Sampling

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

Radiology in the Study of Bone Physiology

RATIONALE AND OBJECTIVES

In this article, we review the core principles of bone physiology alongside imaging examples that demonstrate such principles.

MATERIALS AND METHODS

The core principles of bone physiology are reviewed and further solidified with a corresponding abnormal pathophysiologic example. The key principles of bone physiology to be reviewed include the following: (1) formation and growth, (2) maintenance and repair, (3) metabolism and regulation, and (4) neoplastic disease. Lastly, a collection of secondary bone diseases is presented to demonstrate the skeletal manifestations of numerous systemic diseases. With this integrative method, we hope to emphasize the value of using radiology to teach physiology within a clinical context. This is especially relevant now, as many US medical schools undergo curricular reform with more emphasis on integrative interdisciplinary learning. Ultimately, we intend to provide a paradigm for incorporating radiology into the pre-clinical medical curriculum through a review of basic science physiology that underlies key radiographic findings of the skeletal system.

RESULTS

Radiology is known for its role in helping make diagnoses and clinical decisions. However, radiology is also well suited to enhance medical education by offering the ability to visualize physiology in action. This is especially true in skeletal radiology, where radiographic osseous changes represent a wide range of physiological processes. Therefore, skeletal radiology can be a useful tool for illustrating concepts of physiology that underlie the normal and abnormal radiologic appearances of bone.

CONCLUSION

Radiology is an important but underutilized tool for demonstrating concepts in bone physiology.

Determinants of Calcium Infusion Rate During Continuous Veno-venous Hemofiltration with Regional Citrate Anticoagulation in Critically Ill Patients with Acute Kidney Injury

BACKGROUND

It is unclear that how to decide the calcium infusion rate during continuous veno-venous hemofiltration (CVVH) with regional citrate anticoagulation (RCA). This study aimed to assess the determinants of calcium infusion rate during CVVH with RCA in critically ill patients with acute kidney injury (AKI).

METHODS

A total of 18 patients with AKI requiring CVVH were prospectively analyzed. Postdilution CVVH was performed with a fixed blood flow rate of 150 ml/min and a replacement fluid flow rate of 2000 ml/h for each new circuit. The infusion of 4% trisodium citrate was started at a rate of 29.9 mmol/h prefilter and adjusted according to postfilter ionized calcium. The infusion of 10% calcium gluconate was initiated at a rate of 5.5 mmol/h and adjusted according to systemic ionized calcium. The infusion rate of trisodium citrate and calcium gluconate as well as ultrafiltrate flow rate were recorded at 1, 2, 4, 6, 12, and 24 h after starting CVVH, respectively. The calcium loss rate by CVVH was also calculated.

RESULTS

Fifty-seven sessions of CVVH were performed in 18 AKI patients. The citrate infusion rate, calcium loss rate by CVVH, and calcium infusion rate were 31.30 (interquartile range: 2.70), 4.60 ± 0.48, and 5.50 ± 0.35 mmol/h, respectively. The calcium infusion rate was significantly higher than that of calcium loss rate by CVVH (P < 0.01). The correlation coefficient between the calcium and citrate infusion rates, and calcium infusion and calcium loss rates by CVVH was -0.031 (P > 0.05) and 0.932 (P < 0.01), respectively. In addition, calcium infusion rate (mmol/h) = 1.77 + 0.8 × (calcium loss rate by CVVH, mmol/h).

CONCLUSIONS

The calcium infusion rate correlates significantly with the calcium loss rate by CVVH but not with the citrate infusion rate in a fixed blood flow rate during CVVH with RCA.

Adipose-derived stem cells: A novel source of parathyroid cells for treatment of hypoparathyroidism

Hypoparathyroidism is characterized by decreased function of the parathyroid glands with underproduction of parathyroid hormone (PTH), which can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany, and several other symptoms. Severe hypocalcemia is a life-threatening condition. At present, both medical and surgical treatments are offered to improve the blood calcium, but they are not a cure. Adipose-derived stem cells (ADSCs), derived from the adipose tissue, are confirmed to be multipotent with adipogenic, chondrogenic, neurogenic, myogenic and osteogenic capabilities. Our hypothesis is that human ADSCs in culture can be differentiated into parathyroid cells, and used to reconstitute function.

Acute Symptomatic Seizures Caused by Electrolyte Disturbances

In this narrative review we focus on acute symptomatic seizures occurring in subjects with electrolyte disturbances. Quite surprisingly, despite its clinical relevance, this issue has received very little attention in the scientific literature. Electrolyte abnormalities are commonly encountered in clinical daily practice, and their diagnosis relies on routine laboratory findings. Acute and severe electrolyte imbalances can manifest with seizures, which may be the sole presenting symptom. Seizures are more frequently observed in patients with sodium disorders (especially hyponatremia), hypocalcemia, and hypomagnesemia. They do not entail a diagnosis of epilepsy, but are classified as acute symptomatic seizures. EEG has little specificity in differentiating between various electrolyte disturbances. The prominent EEG feature is slowing of the normal background activity, although other EEG findings, including various epileptiform abnormalities may occur. An accurate and prompt diagnosis should be established for a successful management of seizures, as rapid identification and correction of the underlying electrolyte disturbance (rather than an antiepileptic treatment) are of crucial importance in the control of seizures and prevention of permanent brain damage.

Evaluation of parathyroid function and mineral metabolism in psychiatric patients using lithium salts

OBJECTIVE

To evaluate parathyroid function and mineral metabolism in psychiatric patients users of lithium salts.

MATERIALS AND METHODS

We measured the serum levels of calcium, ionized calcium, inorganic phosphorus, alkaline phosphatase, albumin, parathyroid hormone (PTH), urea, creatinine, 25-hydroxy-vitamin D and lithium of 35 patients diagnosed with bipolar disorder in use of lithium carbonate (LC) for at least one year (Lithium Group - LG) and 35 healthy subjects (Control Group - CG).

RESULTS

The LG and CG were matched by sex and age. There was only statistic difference in relation to the levels of PTH and ionized calcium, with p < 0.004 and p < 0.03, respectively. Secondary form of hyperparathyroidism (HPT) was found in eight (22.8%) LG patients and in none of the CG. There was no correlation between lithemia, usage time and dosage of LC.

CONCLUSION

Our data demonstrate that lithium may create an imbalance in the parathyroid axis, characterized by elevated levels of PTH.

Phosphate binder pill burden, patient-reported non-adherence, and mineral bone disorder markers: Findings from the DOPPS

Because of multiple comorbidities, hemodialysis (HD) patients are prescribed many oral medications, including phosphate binders (PBs), often resulting in a high "pill burden." Using data from the international Dialysis Outcomes and Practice Patterns Study (DOPPS), we assessed associations between PB pill burden, patient-reported PB non-adherence, and levels of serum phosphorus (SPhos) and parathyroid hormone (PTH) using standard regression analyses. The study included data collected from 5262 HD patients from dialysis units participating in the DOPPS in 12 countries. PB prescription ranged from a mean of 7.4 pills per day in the United States to 3.9 pills per day in France. About half of the patients were prescribed at least 6 PB pills per day, and 13% were prescribed at least 12 PB pills per day. Overall, the proportion of patients who reported skipping PBs at least once in the past month was 45% overall, ranging from 33% in Belgium to 57% in the United States. There was a trend toward greater PB non-adherence and a higher number of prescribed PB pills per day. Non-adherence to PB prescription was associated with high SPhos (>5.5 mg/dL) and PTH (>600 pg/mL). Adherence to PB is a challenge for many HD patients and may be related to the number of PB pills prescribed. Prescription of a simplified PB regimen could improve patient adherence and perhaps improve SPhos and PTH levels.

Utilizing time-lapse micro-CT-correlated bisphosphonate binding kinetics and soft tissue-derived input functions to differentiate site-specific changes in bone metabolism in vivo

The turnover of bone is a tightly regulated process between bone formation and resorption to ensure skeletal homeostasis. This process differs between bone types, with trabecular bone often associated with higher turnover than cortical bone. Analyses of bone by micro-computed tomography (micro-CT) reveal changes in structure and mineral content, but are limited in the study of metabolic activity at a single time point, while analyses of serum markers can reveal changes in bone metabolism, but cannot delineate the origin of any aberrant findings. To obtain a site-specific assessment of bone metabolic status, bisphosphonate binding kinetics were utilized. Using a fluorescently-labeled bisphosphonate, we show that early binding kinetics monitored in vivo using fluorescent molecular tomography (FMT) can monitor changes in bone metabolism in response to bone loss, stimulated by ovariectomy (OVX), or bone gain, resulting from treatment with the anabolic bone agent parathyroid hormone (PTH), and is capable of distinguishing different, metabolically distinct skeletal sites. Using time-lapse micro-CT, longitudinal bone turnover was quantified. The spine showed a significantly greater percent resorbing volume and surface in response to OVX, while mice treated with PTH showed significantly greater resorbing volume per bone surface in the spine and significantly greater forming surfaces in the knee. Correlation studies between binding kinetics and micro-CT suggest that forming surfaces, as assessed by time-lapse micro-CT, are preferentially reflected in the rate constant values while forming and resorbing bone volumes primarily affect plateau values. Additionally, we developed a blood pool correction method which now allows for quantitative multi-compartment analyses to be conducted using FMT. These results further expand our understanding of bisphosphonate binding and the use of bisphosphonate binding kinetics as a tool to monitor site-specific changes in bone metabolism in vivo.

Primary hyperparathyroidism in pregnancy: a two-case report and literature review

Primary hyperparathyroidism (PHPT) in pregnant women is an uncommon disease. It could be easily misdiagnosed because of physiologic changes during pregnancy; in some cases, patients could remain asymptomatic maintaining elevated calcium serum levels, and this situation represents a threat to the health of both mother and fetus. We present two cases of PHPT during pregnancy and their evolution after surgical treatment in the second trimester; there were no observed complications during pregnancy or delivery in our patients. Early diagnosis and medical/surgical treatment in PHPT are necessary for avoiding maternal and fetal complications which could not be predicted based on duration or severity of hypercalcemia. An appropriate management of PHPT during pregnancy is necessary for preserving the health of both the woman and the fetus.

Functional characterization of a CDKN1B mutation in a Sardinian kindred with multiple endocrine neoplasia type 4 (MEN4)

Inactivating germline mutations of the CDKN1B gene, encoding for the nuclear cyclin-dependent kinase inhibitor p27kip1 protein, have been reported in patients with multiple endocrine neoplasia type 4 (MEN4), a MEN1-like phenotype without MEN1 mutations. The aim of this study was to in vitro characterize the germline CDKN1B mutation c.374_375delCT (S125X) we detected in a patient with MEN4. The proband was affected by multiglandular primary hyperparathyroidism and gastro-entero-pancreatic tumors. We carried out subcellular localization experiments transfecting into eukaryotic HeLa and GH3 cell lines plasmid vectors expressing the CDKN1B wild type (wt) or mutant cDNA. Western blot studies showed that fusion proteins were expressed at equal levels. The mutated protein was shorter compared to the wt protein and lacked the highly conserved C-terminal domain, which includes the bipartite nuclear localization signal at amino acids 152/153 and 166/168. In HeLa and GH3 cells wt p27 localized in the nucleus whereas the p27_S125X protein was retained in the cytoplasm predicting the loss of tumor suppressive function. The proband's tumoral parathyroid tissue did not show allelic loss, since wt and mutant alleles were both present by sequencing the somatic DNA. Immunohistochemistry showed a complete loss of nuclear p27 expression in the parathyroid adenoma removed by the patient at the second surgery. In conclusion, our study confirms the pathogenic role of the c.374_375delCT CDKN1B germline mutation in a patient with MEN4.

Evaluation of conventional imaging techniques on preoperative localization in primary hyperparathyroidism

We aimed to evaluate the diagnostic and preoperative localization capacity of 99mTc methoxyisobutylnitrile (MIBI) parathyroid scintigraphy and ultrasonography (USG) in enlarged parathyroid glands in the primary hyperparathyroidism (pHPT) as well as the relationship between the success rate of these techniques and biochemical values. In this study, we retrospectively evaluated 39 patients with clinical and biological evidence of pHPT who referred to the university hospital for MIBI parathyroid scintigraphy. Patients were examined with USG and double-phase MIBI parathyroid scintigraphy for the detection of enlarged parathyroid glands. Preoperative serum intact parathyroid hormone (iPTH) levels, calcium (Ca), phosphate and alkaline phosphatase measurements were obtained. A total of 45 parathyroid lesions in 39 patients were reviewed. Thirty-four patients had a single adenoma and 5 patients with multi-gland disease had 11 abnormal parathyroid glands including three adenomas, whereas the remaining 8 glands showed hyperplasia. The overall sensitivities of MIBI parathyroid scintigraphy, USG and combined techniques were 85.3%, 72.5% and 90.4%, respectively; the positive predictive values (PPV) were 89.7%, 85.2% and 92.6%, respectively. The most successful approach for detection of enlarged parathyroid glands in hyperparathyroidism is the concurrent application of USG and MIBI parathyroid scintigraphy modalities. The concomitancy of thyroid diseases decreases the sensitivity of both MIBI parathyroid scintigraphy and USG in enlarged parathyroid glands.

[Risk of hypocalcemia after thyroid surgery]

AIM

To reveal calcium metabolism disorders that frequently occur after thyroid surgery.

MATERIAL AND METHODS

The study included 202 patients who underwent thyroid surgery for different diseases and had normal calcium level in peripheral blood at baseline.

RESULTS

Based on laboratory data postoperative hypocalcemia was diagnosed in 57 (28.8%) patients. It was not always accompanied by clinical symptoms. Clinical picture depended on degree of hypocalcemia. Symptoms was diagnosed more frequently if calcium concentration was less than 2.1 mmol/l. Clinical manifestations were absent in 64.9% of cases on background of hypocalcemia. Incidence of hypocalcemia was higher after thyroidectomy compared to organ-preserving surgery. Symptoms of hypocalcemia occurred after thyroidectomy only. Casual parathyroidectomy does not always cause hypocalcemia. Only in 14% of patients with hypocalcemia excised parathyroid was identified in specimen. At the same time 7.6% of patients with postoperative normocalcaemia also had excised parathyroids in specimens. Symptoms of hypocalcemia does not always occur at 1 day after surgery. They can appear later, for example at 5 days postoperatively and depend on severity of hypocalcemia. Thyroidectomy has high risk of postoperative hypocalcemia with clinical symptoms (19.6%) that is transient in 15.5% of cases and permanent in 4.1% of patients.

Rapid progression of vascular and soft tissue calcification while being managed for severe and persistent hypocalcemia induced by denosumab treatment in a patient with multiple myeloma and chronic kidney disease

We herein present the case of a patient with myeloma and chronic kidney disease (CKD) who developed rapidly progressive vascular and soft tissue calcification during the course of treatment for severe hypocalcemia induced by the administration of denosumab for myeloma and hypercalcemia. Because a large amount of supplementation with active vitamin D and calcium was required to correct the severe hypocalcemia, rapidly progressive vascular calcification developed. Seeing that patients with CKD are prone to developing severe and prolonged hypocalcemia after denosumab treatment, physicians should closely monitor the patients' serum calcium levels and manage their hypocalcemia appropriately so as to avoid the development of significant ectopic calcification.

Postsurgical hypoparathyroidism--risk of fractures, psychiatric diseases, cancer, cataract, and infections

Data on co-morbidity in patients with postsurgical hypoparathyroidism (HypoPT) are sparse. We aimed to assess risk of fractures, spinal stenosis, cataract, neuropsychiatric diseases, cancer, and infections within the historic cohort of patients with postsurgical HypoPT due to non-malignant causes that we previously have characterized. Patients were identified through the Danish National Patient Registry and regional prescription databases, with subsequent validation of their individual hospital records. Identified cases were matched with three age- (± 2 yr) and gender-matched controls from the general background population. Compared with controls, patients did not have an increased risk of cataract (p = 0.52), spinal stenosis (p = 0.59), or any fracture (p = 0.98). However, the risk of fractures at the upper extremities was significantly decreased in patients (HR 0.69, 95% CI 0.49-0.97). Compared with controls, patients had a significantly increased risk of hospitalization due to infections (HR 1.42, 95% CI 1.20-1.67) and depression/bipolar affective disorders (HR 1.99, 95% CI 1.14-3.46). The risk of malignant diseases did not differ between groups although the risk of gastrointestinal cancers was significantly lower in patients compared with controls (HR 0.63, 95% CI 0.44-0.93). In conclusion, HypoPT is associated with an increased risk of depression and other types of neuropsychiatric diseases as well as infections, whereas patients seem to be protected against fractures at the upper extremities and gastrointestinal malignancies.

Evaluation of left ventricle functions by tissue Doppler, strain, and strain rate echocardiography in patients with primary hyperparathyroidism

Cardiovascular morbidity and mortality are increased in patients with primary hyperparathyroidism (PHPT). We aimed to evaluate left ventricle systolic and diastolic functions with tissue Doppler imaging (TDI) and strain and strain rate echocardiography in patients with PHPT. Thirty-one patients with PHPT and 29 healthy controls were evaluated with conventional and pulse Doppler echocardiography, TDI and strain and strain rate echocardiography. Myocardial performance index (MPI) was calculated. Strain and peak systolic strain rate in mid and basal segments of lateral, anterior, inferior, and septal walls of left ventricle were determined. TDI showed similar late diastolic myocardial peak velocity in two groups. Peak systolic mitral annular velocity, early diastolic myocardial peak velocity, and ratio of early to late diastolic myocardial peak velocity were lower in PHPT patients (p = 0.01, p < 0.001 and p < 0.001, respectively). MPI calculated by TDI was 0.53 ± 0.15 in PHPT group and 0.44 ± 0.09 in control group (p = 0.013). Strain values were lower in mid and basal segments of septum, lateral and anterior walls, and basal segment of inferior wall in PHPT patients. Mean systolic strain was -20.88 ± 2.30 and -24.25 ± 2.13 in PHPT patients and control group, respectively (p < 0.001). Mean strain rate was lower in PHPT patients compared to control group (-1.38 ± 0.19 vs -1.57 ± 0.25) (p = 0.002). Patients with PHPT, but no cardiac symptoms or documented cardiovascular disease, have subclinical systolic and diastolic myocardial dysfunction. Evaluation of these patients with TDI and S and Sr echocardiography in addition to conventional echocardiography might be valuable to detect subclinical cardiac involvement.

Dental manifestation of primary idiopathic hypoparathyroidism

Idiopathic hypoparathyroidism (IHP) is a rare endocrinopathic disorder, of idiopathic nature, characterized by a deficiency of parathyroid hormone causing low serum calcium (Ca) and high serum phosphorus concentrations. We present a case report ofa 40-year-old woman with complaint of bleeding gums and tingling sensation in fingers and toes reported to our department in March 2005 with no tangible diagnosis from previous medical examinations. Oral findings included abnormally short roots, cemental hyperplasia, widening of the periodontal ligament space and root resorption. Laboratory investigations revealed a low serum Ca level and along with the clinical findings, a diagnosis of IHP was reached. Oral prophylaxis was performed and Ca supplements were prescribed. We believe that this case report is a first of its kind reporting cemental hyperplasia, altered alveolar bone patterns and periodontal ligament widening in a patient with IHP.

First evidence of TRPV5 and TRPV6 channels in human parathyroid glands: possible involvement in neoplastic transformation

The parathyroid glands play an overall regulatory role in the systemic calcium (Ca²⁺) homeostasis. The purpose of the present study was to demonstrate the presence of the Ca²⁺ channels transient receptor potential vanilloid (TRPV) 5 and TRPV6 in human parathyroid glands. Semi-quantitative and quantitative PCR was carried out to evaluate the presence of TRPV5 and TRPV6 mRNAs in sporadic parathyroid adenomas and normal parathyroid glands. Western blot and immunocytochemical assays were used to assess protein expression, cellular localization and time expression in primary cultures from human parathyroid adenoma. TRPV5 and TRPV6 transcripts were then identified both in normal and pathological tissues. Predominant immunoreactive bands were detected at 75–80 kD for both vanilloid channels. These channels co-localized with the calcium-sensing receptor (CASR) on the membrane surface, but immunoreactivity was also detected in the cytosol and around the nuclei. Our data showed that western blotting recorded an increase of protein expression of both channels in adenoma samples compared with normal glands suggesting a potential relation with the cell calcium signalling pathway and the pathological processes of these glands.

Genetic basis of familial isolated hyperparathyroidism: a case series and a narrative review of the literature

Primary hyperparathyroidism is a heterogeneous clinical entity. In the clinical setting, the diagnosis and management of familial isolated hyperparathyroidism (FIHP) and other familial hyperparathyroidism (FHPT) forms continue to rely on clinical, laboratory, and histological findings, with careful examination of the family. In this article, we report a case series of FIHP in a four-generation Greek family, with no identifiable gene mutations. Clinical approach and long-term follow-up are discussed and a narrative review of the genetic basis of this entity has been performed.

Electroencephalography of encephalopathy in patients with endocrine and metabolic disorders

Patients with acute alteration in mental status from encephalopathy because of underlying metabolic-toxic or endocrine abnormalities are frequently seen in the acute hospital setting. A rapid diagnosis and correction of the underlying cause is essential as a prolonged state of encephalopathy portends a poor outcome. Correct diagnosis and management remain challenging because several encephalopathies may present similarly, and further laboratory, imaging, or other testing may not always reveal the underlying cause. EEG provides rapid additional information on the encephalopathic patient. It may help establish the diagnosis and is indispensable for identifying nonconvulsive status epilepticus, an important possible complication in this context. The EEG may assist the clinician in gauging the severity of brain dysfunction and may aid in predicting outcome. This review summarizes the current knowledge on EEG findings in selected metabolic and endocrine causes of encephalopathy and highlights distinct EEG features associated with particular etiologies.

Giant cell tumor of bone in a patient with diagnosis of primary hyperparathyroidism: a challenge in differential diagnosis with brown tumor

Giant cell lesions of bone share similar clinical, radiological, and histological features. The most challenging differential diagnosis is between giant cell tumor (GCT) and brown tumor (BT) secondary to hyperparathyroidism. Differential diagnosis is based on determining serum calcium concentration and other markers of calcium metabolism. The authors present the unusual case of a 37-year-old Caucasian woman affected by a GCT of the proximal left tibia and concomitant asymptomatic primary hyperparathyroidism (PHPT) due to a parathyroid adenoma. The presence of two concurrent diseases complicated diagnosis and relative treatment. The patient was first treated for the adenoma, then after 9 months, she underwent curettage of tibial GCT. Denosumab treatment was administered for 12 months to control a relapse occurring at 15 months post-curettage. At 32-month follow-up from primary tibial surgery, the patient was free from tumor disease. To our knowledge, this is the first case in the literature reporting the concomitant presence of asymptomatic PHPT and GCT. The possibility of concomitant finding these two diseases has to be considered during the decision-making process.

Missense mutation in the MEN1 gene discovered through whole exome sequencing co-segregates with familial hyperparathyroidism

Familial isolated hyperparathyroidism (FIHP) can be encountered in the context of multiple endocrine neoplasia type 1 (MEN1), hyperparathyroidism and jaw tumour syndrome (HPT-JT) and in familial hypocalciuric hypercalcaemia (FHH). In these syndromes, germline mutations in the relevant genes (MEN1, HPRT2 and CaSR, respectively) are detected. In some FIHP cases, the causative gene is still elusive. The objective of this study is to define the genetic basis of FIHP in a Georgian Jewish family with FIHP using whole exome capture and sequencing. DNA extracted from two sibs and one offspring from a single family all affected with multiglandular hyperparathyroidism was subjected to whole exome capturing and sequencing using the Roche NimbleGen V2 chip and the Illumina HiSeq2000 sequencing platform. Genetic variants were detected and annotated using a combination of the Genome Analysis Tool Kit and in-house scripts. Subsequent confirmation of the mutations and co-segregation analyses were carried out by Sanger sequencing in additional affected and unaffected family members. Whole exome capture and sequencing revealed the collection of variations common to the three-sequenced patients, including a very rare previously described missense mutation (c.T1021C: p.W341R) in the MEN1 gene. The p.W341R mutation in the MEN1 gene showed complete co-segregation in the family. Whole exome capture and sequencing led to the discovery of a missense mutation in the MEN1 gene and ruling out of the additional candidates in a single experiment. The limited expressivity of this mutation may imply a specific genotype-phenotype correlation for this mutation.

PTH: Potential role in management of heart failure

Biomarkers play an important role for the diagnosis and prognosis of heart failure (HF), a disease with high morbidity and mortality as well as a huge impact on healthcare budgets. Parathyroid hormone (PTH) is a major systemic calcium-regulating hormone and an important regulator of bone and mineral homeostasis. PTH testing is important for differential diagnosis of calcemia related disorders and for the management of patients with chronic kidney disease. As secondary hyperparathyroidism has been evidenced in HF patients, PTH testing might be relevant in HF patients for risk stratification and more personalized selection of treatment.

Inherited disorders of calcium and phosphate metabolism

PURPOSE OF REVIEW

Inherited disorders of calcium and phosphate homeostasis have variable presentation and can cause significant morbidity. An understanding of the mode of inheritance and pathophysiology of these conditions will help in the diagnosis and early institution of therapy.

RECENT FINDINGS

Identification of genetic mutations in humans and animal models has advanced our understanding of many inherited disorders of calcium and phosphate regulation. Identification of mutations of calcium-sensing receptor has improved our understanding of hypocalcemic and hypercalcemic conditions. Mutations of Fgf23, Klotho and phosphate transporter genes have been identified to cause disorders of phosphate metabolism.

SUMMARY

Calcium and phosphate homeostasis is tightly regulated in a narrow range due to their vital role in many biological processes. Inherited disorders of calcium and phosphate metabolism though uncommon can have severe morbidity. Genetic counseling of the affected families is an important part of the follow-up of these patients.

The histone methyltransferase EZH2, an oncogene common to benign and malignant parathyroid tumors

Primary hyperparathyroidism (pHPT) resulting from parathyroid tumors is a common endocrine disorder with incompletely understood etiology. In renal failure, secondary hyperparathyroidism (sHPT) occurs with multiple tumor development as a result of calcium and vitamin D regulatory disturbance. The aim of this study was to investigate a potential role of the histone 3 lysine 27 methyltransferase EZH2 in parathyroid tumorigenesis. Parathyroid tumors from patients with pHPT included adenomas and carcinomas. Hyperplastic parathyroid glands from patients with HPT secondary to uremia and normal parathyroid tissue specimens were included in this study. Quantitative RT-PCR, western blotting, bisulfite pyrosequencing, colony formation assay, and RNA interference were used. EZH2 was overexpressed in a subset of the benign and in all malignant parathyroid tumors as determined by quantitative RT-PCR and western blotting analyses. Overexpression was explained by EZH2 gene amplification in a large fraction of tumors. EZH2 depletion by RNA interference inhibited sHPT-1 parathyroid cell line proliferation as determined by tritium-thymidine incorporation and colony formation assays. EZH2 depletion also interfered with the Wnt/β-catenin signaling pathway by increased expression of growth-suppressive AXIN2, a negative regulator of β-catenin stability. Indeed, EZH2 contributed to the total level of aberrantly accumulated transcriptionally active (nonphosphoylated) β-catenin in the parathyroid tumor cells. To our knowledge EZH2 gene amplification presents the first genetic aberration common to parathyroid adenomas, secondary hyperplastic parathyroid glands, and parathyroid carcinomas. This supports the possibility of a common pathway in parathyroid tumor development.

Musculoskeletal manifestations of endocrine disorders

Endocrine disorders can lead to disturbances in numerous systems within the body, including the musculoskeletal system. Radiological evaluation of these conditions can demonstrate typical appearances of the bones and soft tissues. Knowledge of these patterns can allow the radiologist to suggest a diagnosis that may not be clinically apparent. This review will highlight the typical musculoskeletal findings of acromegaly, hypercortisolism, hyperthyroidism, hypothyroidism, hyperparathyroidism, pseudo- and pseudopseudohypoparathyroidism, and diabetes mellitus. The radiological manifestations of each of these endocrine disorders, along with a brief discussion of the pathophysiology and clinical implications, will be discussed.

Two Cases of Metastatic Parathyroid Carcinoma in Male C3H Mice Following Irradiation

White nodules were observed in the thyroid in two male C3H mice (at 99 and 122 weeks of age) exposed to fast neutrons at the age of 8 weeks. Histopathologically, in both cases, tumors were developed in the region corresponding to the parathyroid gland, and the tumor cells were arranged in a solid sheet or nest-like structures. Necrosis, cell debris and/or hemorrhage were sometimes seen in the center of the tumor structures. Tumor cells were small and uniform with scanty cytoplasm, cell margins were indistinct, and basally located tumor cells were aligned along the vascular stroma. Mitotic figures were frequently observed. Metastasis to the renal cortex was observed in both cases. These cases were diagnosed as parathyroid carcinoma. A parathyroid tumor is an extremely rare endocrine tumor in mice, regardless of whether the tumor is spontaneous or experimentally induced. These cases may have been induced by neutron-exposure; however, how radiation induces parathyroid carcinoma in mice is not clear.

Gene identification of potential malignant parathyroid tumors phenotype in Chinese population

Parathyroid carcinoma is a rare tumor associated with poor prognosis, thus early preoperative recognition and surgical resection are critical. However, because of a lack of definitive diagnostic markers and typical clinical features, it is difficult to diagnose this disease in its early stages and it is often misdiagnosed as parathyroid adenoma. Additionally, little is known about the molecular pathogenesis of parathyroid carcinoma because of its rarity. To better understand the molecular genetics of parathyroid carcinoma in the Chinese population, we undertook gene expression profiling of eight parathyroid tumors (five parathyroid adenomas and three parathyroid carcinomas) and five normal parathyroid samples. Differential gene sets between the groups were identified, which may serve as diagnostic biomarkers. Using both gene and protein expression, we demonstrated that CD24, HMOX1, VCAM1 and KCNA3 are useful markers for parathyroid carcinoma. Our findings provide insights into the molecular mechanisms of parathyroid tumorigenesis and may help to improve the diagnosis and treatment of parathyroid carcinoma.

Prevalence and incidence of hypoparathyroidism in the United States using a large claims database

Hypoparathyroidism is a rare endocrine disorder whose incidence and prevalence have not been well defined. This study aimed to 1) estimate the number of insured adult patients with hypoparathyroidism in the United States and 2) obtain physician assessment of disease severity and chronicity. Prevalence was estimated through calculation of diagnoses of hypoparathyroidism in a large proprietary health plan claims database over a 12-month period from October 2007 through September 2008 and projected to the US insured population. Incidence was also calculated from the same database by determining the proportion of total neck surgeries resulting in either transient (≤6 months) or chronic (>6 months) hypoparathyroidism. A physician primary market research study was conducted to assess disease severity and determine the percentage of new nonsurgical patients with hypoparathyroidism. Incidence data were entered into an epidemiologic model to derive an estimate of prevalence. The diagnosis-based prevalence approach estimated 58,793 insured patients with chronic hypoparathyroidism in the United States. The surgical-based incidence approach yielded 117,342 relevant surgeries resulting in 8901 cases over 12 months. Overall, 7.6% of surgeries resulted in hypoparathyroidism (75% transient, 25% chronic). The prevalence of chronic hypoparathyroidism among insured patients included in the surgical database was estimated to be 58,625. The physician survey found that 75% of cases treated over the past 12 months were reported due to surgery and, among all thyroidectomies and parathyroidectomies and neck dissections performed in a year, 26% resulted in transient hypoparathyroidism and 5% progressed to a chronic state. In conclusion, the two claims-based methods yielded similar estimates of the number of insured patients with chronic hypoparathyroidism in the United States (~58,700). The physician survey was consistent with those calculations and confirmed the burden imposed by hypoparathyroidism.

Cardiovascular and renal complications to postsurgical hypoparathyroidism: a Danish nationwide controlled historic follow-up study

We aimed to identify all patients with postsurgical hypoparathyroidism (HypoPT) and to evaluate their risks of renal complications and cardiovascular disease in relation to their disease and its treatment. We identified possible patients through the Danish National Patient Registry and a prescription database. Case status was adjudicated by review of individual patients' hospital records. For each patient with postsurgical HypoPT due to surgery for nonmalignant diseases between 1988 and 2012, three age-matched (± 2 years) and gender-matched controls were selected from the general background population. The prevalence of postsurgical HypoPT was 22 per 100,000 inhabitants. We identified 688 patients who had undergone neck surgery since 1988 with subsequent hypocalcaemia and inappropriate low parathyroid hormone (PTH) levels that necessitated treatment with calcium and/or vitamin D supplementation for more than 6 months. The average age at diagnosis was 49 years (range, 17-87 years), and 88% were women. Sixteen percent of all patients had had neck surgery prior to the operation causing HypoPT. Compared with controls, patients with HypoPT had an increased risk of renal complications (hazard ratio [HR], 3.67; 95% confidence interval [CI], 2.41-5.59) and hospitalization due to seizures (HR, 3.82; 95% CI, 2.15-6.79), whereas there was no increased risk of cardiac arrhythmias (HR, 1.11; 95% CI, 0.79-1.57) or cardiovascular disease or death (HR, 0.89; 95% CI, 0.73-1.09). In conclusion, although risk of seizures and renal complications is increased, mortality and risk of cardiovascular diseases or arrhythmias is not increased in patients with HypoPT. Further study should try to determine how to reduce the risk of seizures and renal complications in HypoPT.

CDC73 mutational status and loss of parafibromin in the outcome of parathyroid cancer

Inactivating mutations of the CDC73 tumor suppressor gene have been reported in parathyroid carcinomas (PC), in association with the loss of nuclear expression of the encoded protein, parafibromin. The aim of this study was to further investigate the role of the CDC73 gene in PC and evaluate whether gene carrier status and/or the loss of parafibromin staining might have an effect on the outcome of the disease. We performed genetic and immunohistochemical studies in parathyroid tumor samples from 35 patients with sporadic PC. Nonsense or frameshift CDC73 mutations were detected in 13 samples suitable for DNA sequencing. Six of these mutations were germline. Loss of parafibromin expression was found in 17 samples. The presence of the CDC73 mutation as well as the loss of parafibromin predicted a high likelihood of subsequent recurrence and/or metastasis (92.3%, P=0.049 and 94.1%, P=0.0017 respectively), but only the latter was associated with a decreased overall 5- and 10-year survival rates (59%, P=0.107, and 23%, P=0.0026 respectively). The presence of both the CDC73 mutation and loss of parafibromin staining compared with their absence predicted a lower overall survival at 10- (18 vs 84%, P=0.016) but not at 5-year follow-up. In conclusion, loss of parafibromin staining, better than CDC73 mutation, predicts the clinical outcome and mortality rate. The added value of CDC73 mutational analysis is the possibility of identifying germline mutations, which will prompt the screening of other family members.

Pathology, pathophysiology, and treatment strategies of endocrine disorders and their cardiac complications

The cardiovascular system is affected by a multitude of endocrine disorders, including dysfunction of the thyroid, calcium, glucocorticoids, insulin/glucose, and growth hormone axes. Since most of these changes in the cardiovascular system are reversible when treated, early diagnosis is important, as if left untreated, they may become fatal. This review focuses on the pathophysiology, clinical presentation, pathology, and treatment of patients with these endocrine diseases who present with a variety of cardiovascular manifestations. Neuroendocrine tumors presenting with the carcinoid syndrome and their cardiovascular manifestations are also discussed.