Long-term treatment of 12 children with chronic hypoparathyroidism: a randomized trial comparing synthetic human parathyroid hormone 1-34 versus calcitriol and calcium

Hypoparathyroidism: an update on new therapeutic approaches

BACKGROUND

Hypoparathyroidism is a rare endocrine disease characterized by insufficient parathyroid hormone (PTH) secretion by the parathyroid glands, leading to hypocalcemia. In contrast to most hormone deficiencies for which hormone replacement is currently the mainstay of therapy, hypoparathyroidism has conventionally been treated with calcium supplements and active analogs of vitamin D. Although the advent of a replacement therapy with 1-34 and 1-84 PTH represented a major step in the therapeutic history of hypoparathyroidism, several new molecules and different management strategies have recently been developed.

PURPOSE

This review investigates the therapeutic approaches currently under investigation for the treatment of hypoparathyroidism. Clinical trials results have been considered and discussed.

Recombinant PTH Infusion in a Child With Sanjad-Sakati Syndrome Refractory to Conventional Therapy

Hypoparathyroidism is the most common endocrinological feature in children with Sanjad-Sakati syndrome. Treatment includes active vitamin D and calcium supplementation. Here, we report a case of a newborn with Sanjad-Sakati syndrome who had severe hypocalcemia since birth who responded to PTH subcutaneous pump infusion. The child was born at 35 weeks with hypocalcemia since the first day of life. The standard medical treatment proved ineffective for the newborn, necessitating the administration of unusually high doses of oral and IV calcium and vitamin D analogue for a 2 months. As a result, intermittent subcutaneous injections of PTH were commenced, resulting in an initial improvement in calcium levels, although this proved to be short-lived. Subsequently, a switch to continuous infusion via a Medtronic Vio pump was made, which unfortunately resulted in iatrogenic hypercalcemia, requiring management of hypercalcemia. Later, calcium carbonate and alfacalcidol were resumed at a lower dosage and continued to have average requirements for patients with hypoparathyroidism. PTH subcutaneous infusion can be highly effective in refractory hypocalcemia cases and can significantly impact the treatment course and facilitate hospital discharge as seen in our case. Careful dosage and monitoring are required to avoid iatrogenic hypercalcemia.

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.

Transitory Activation and Improved Transition from Erosion to Formation within Intracortical Bone Remodeling in Hypoparathyroid Patients Treated with rhPTH(1-84)

In hypoparathyroidism, lack of parathyroid hormone (PTH) leads to low calcium levels and decreased bone remodeling. Treatment with recombinant human PTH (rhPTH) may normalize bone turnover. This study aimed to investigate whether rhPTH(1-84) continued to activate intracortical bone remodeling after 30 months and promoted the transition from erosion to formation and whether this effect was transitory when rhPTH(1-84) was discontinued. Cortical histomorphometry was performed on 60 bone biopsies from patients (aged 31 to 78 years) with chronic hypoparathyroidism randomized to either 100 μg rhPTH(1-84) a day (n = 21) (PTH) or similar placebo (n = 21) (PLB) for 6 months as add-on to conventional therapy. This was followed by an open-label extension, where patients extended their rhPTH(1-84) (PTH) (n = 5), continued conventional treatment (CON) (n = 5), or withdrew from rhPTH(1-84) and resumed conventional therapy (PTHw) for an additional 24 months (n = 8). Bone biopsies were collected at months 6 (n = 42) and 30 (n = 18). After 6 and 30 months, the overall cortical microarchitecture (cortical porosity, thickness, pore density, and mean pore diameter) in the PTH group did not differ from that of the PLB/CON and PTHw groups. Still, the PTH group had a significantly and persistently higher percentage of pores undergoing remodeling than the PLB/CON groups. A significantly higher percentage of these pores was undergoing bone formation in the PTH compared with the PLB/CON groups, whereas the percentage of pores with erosion only was not different. This resulted in a shift in the ratio between formative and eroded pores, reflecting a faster transition from erosion to formation in the PTH-treated patients. In the rhPTH(1-84) withdrawal group PTHw, the latter effects of PTH were completely reversed in comparison to those of the PLB/CON groups. In conclusion, rhPTH(1-84) replacement therapy in hypoparathyroidism patients promotes intracortical remodeling and its transition from erosion to formation without affecting the overall cortical microstructure. The effect persists for at least 30 months and is reversible when treatment is withdrawn. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

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).

Parathyroid Hormone Therapy for Managing Chronic Hypoparathyroidism: A Systematic Review and Meta-Analysis

The efficacy and safety of parathyroid hormone (PTH) therapy for managing long-term hypoparathyroidism is being evaluated in ongoing clinical trials. We undertook a systematic review and meta-analysis of currently available randomized controlled trials to investigate the benefits and harms of PTH therapy and conventional therapy in the management of patients with chronic hypoparathyroidism. To identify eligible studies, published in English, we searched Embase, PubMed, and Cochrane CENTRAL from inception to May 2022. Two reviewers independently extracted data and assessed the risk of bias. We defined patients' important outcomes and used grading of recommendations, assessment, development, and evaluation (GRADE) to provide the structure for quantifying absolute effects and rating the quality of evidence. Seven randomized trials of 12 publications that enrolled a total of 386 patients proved eligible. The follow-up duration ranged from 1 to 36 months. Compared with conventional therapy, PTH therapy probably achieves a small improvement in physical health-related quality of life (mean difference [MD] 3.4, 95% confidence interval [CI] 1.5-5.3, minimally important difference 3.0, moderate certainty). PTH therapy results in more patients reaching 50% or greater reduction in the dose of active vitamin D and calcium (relative risk [RR] = 6.5, 95% CI 2.5-16.4, 385 more per 1000 patients, high certainty). PTH therapy may increase hypercalcemia (RR =2.4, 95% CI 1.2-5.04, low certainty). The findings may support the use of PTH therapy in patients with chronic hypoparathyroidism. Because of limitations of short duration and small sample size, evidence from randomized trials is limited regarding important benefits of PTH therapy compared with conventional therapy. Establishing such benefits will require further studies. © 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).

Treatment options in hypoparathyroidism

Hypoparathyroidism remains the single endocrine deficiency disease that is not habitually treated with the missing hormone. In this article, we aim to provide a review of the conventional approach and the novel therapies as well as an overview of the perspectives on the treatment of this rare condition. We conducted a literature review on the conventional therapy using vitamin D analogs and calcium salts, indications for thiazide diuretics and phosphorus binders, PTH analogs history and usage, and the drugs that are currently being tested in clinical trials. Conventional treatment involves calcium salts and vitamin D analogs. Thiazide diuretics can be used to reduce hypercalciuria in some cases. A low-phosphate diet is recommended, and phosphate binders are rarely needed. During pregnancy, a careful approach is necessary. The use of PTH analogs is a new approach despite the limitation of high cost. Studies have included modified PTH molecules, calcilytics, microencapsulation of human parathyroid cells, and allotransplantation.

Multicenter retro-prospective observational study on chronic hypoparathyroidism and rhPTH (1-84) treatment

PURPOSE

The main purpose of this study was to investigate the effects of 12 months of rhPTH (1-84) (Natpar^®) treatment in a cohort of patients selected according to the indications of hypoparathyroidism guidelines. The use of recombinant human PTH (1-84) [rhPTH (1-84)] is approved as hormonal replacement therapy in patients with hypoparathyroidism not adequately controlled with conventional therapy.

METHODS

It is a multicenter, observational, retro-prospective, open label study. Eleven Italian Endocrinological centers, members of Hypoparathyroidism Working Group of the Italian Society of Endocrinology (HypoparaNET) were involved. Main outcome measures were serum and urinary calcium and phosphate concentration, calcium-phosphate product, renal function, oral calcium and vitamin D doses, and clinical manifestations.

RESULTS

Fourteen adult subjects, affected by chronic hypoparathyroidism, were treated with rhPTH (1-84) for 12 months. At 12 months of rhPTH (1-84) treatment, 61.5% of patients discontinued calcium supplement and 69.2% calcitriol. Mean albumin-adjusted total serum calcium levels quickly normalized after initiation of rhPTH (1-84) treatment compared to baseline (p = 0.009), remaining in the normal range until 12 months. Rare hypo-hypercalcemia episodes were reported. Renal function was maintained normal and no renal complications were reported. Serum and urinary phosphate and urinary calcium were maintained in the normal range. Mean phosphatemia levels linearly decreased from 3 months up to 12 months compared to baseline (p = 0.014). No severe adverse events were described.

CONCLUSIONS

Biochemical and clinical results confirm the efficacy and safety of rhPTH (1-84) therapy, which represents an important option for hypoparathyroid patients unresponsive to conventional therapy.

Safety and Efficacy of PTH 1-34 and 1-84 Therapy in Chronic Hypoparathyroidism: A Meta-Analysis of Prospective Trials

Hypoparathyroidism is the only endocrine deficiency for which hormone replacement therapy is not the standard of care. Although conventional treatments may control hypocalcaemia, other complications such as hyperphosphatemia, kidney stones, peripheral calcifications, and bone disease remain unmet needs. This meta-analysis (PROSPERO registration number CRD42019126881) aims to evaluate and compare the efficacy and safety of PTH_1-34 and PTH_1-84 in restoring calcium metabolism in chronic hypoparathyroidism. EMBASE, PubMed, and CENTRAL databases were searched for randomized clinical trials or prospective studies published between January 1996 and March 2021. English-language trials reporting data on replacement with PTH_1-34 or PTH_1-84 in chronic hypoparathyroidism were selected. Three authors extracted outcomes, one author performed quality control, all assessed the risk of biases. Overall, data from 25 studies on 588 patients were analyzed. PTH therapy had a neutral effect on calcium levels, while lowering serum phosphate (-0.21 mmol/L; 95% confidence interval [CI], -0.31 to -0.11 mmol/L; p < 0.001) and urinary calcium excretion (-1.21 mmol/24 h; 95% CI, -2.03 to -0.41 mmol/24 h; p = 0.003). Calcium phosphate product decreased under PTH_1-84 therapy only. Both treatments enabled a significant reduction in calcium and calcitriol supplementation. PTH therapy increased bone turnover markers and lumbar spine mineral density. Quality of life improved and there was no difference in the safety profile between PTH and conventionally treated patients. Results for most outcomes were similar for the two treatments. Limitations of the study included considerable population overlap between the reports, incomplete data, and heterogeneity in the protocol design. In conclusion, the meta-analysis of data from the largest collection to date of hypoparathyroid patients shows that PTH therapy is safe, well-tolerated, and effective in normalizing serum phosphate and urinary calcium excretion, as well as enabling a reduction in calcium and vitamin D use and improving quality of life. © 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).

[Experience in using teriparatide for the treatment of postoperative hypoparathyroidism in hemodialysis patients]

The frequency of chronic postoperative hypoparathyroidism after total parathyroidectomy for secondary and tertiary hyperparathyroidism in patients with end-stage renal failure, according to various authors, can reach 20% or more. Prescribing active metabolites of vitamin D and calcium it is not always sufficient for achievement of target goals. This dictates the need for replacement therapy with recombinant parathyroid hormone. Teriparatide is the only drug of this series approved by the American Food and Drug Administration (FDA) and registered in the Russian Federation. However, it is registered as an anabolic anti-osteoporotic drug and is not indicated for the treatment of chronic hypoparathyroidism. The use of teriparatide in postoperative hypoparathyroidism in patients receiving renal replacement therapy with programmed hemodialysis in the Russian Federation has not been previously studied. Data on this issue is also limited in foreign literature. However, it is a potential treatment option for hemodialysis patients with chronic hypoparathyroidism and severe bone disorders. In this article, we present 2 clinical cases of substitution and anabolic therapy with teriparatide in this cohort of patients.

Teriparatide administration by the Omnipod pump: preliminary experience from two cases with refractory hypoparathyroidism

CONTEXT

Hypoparathyroidism (hypoPTH) in adults is mainly due to total thyroidectomy. Conventional therapies (calcium, active vitamin D) can fail to normalize calcemia, expose the patient to hypercalciuria and impact quality-of-life. Human parathormone (PTH) replacement therapy is a suitable option in these cases, although few clinical reports have been published so far.

METHODS

We describe two cases of patients with refractory postsurgical hypoPTH, in whom subcutaneous infusion of recombinant PTH (teriparatide) through the Omnipod® pump was initiated after failure of all other therapeutic options. Besides, we performed a review of literature of hypoPTH cases treated by continuous infusion of teriparatide.

RESULTS

Two women aged 46 and 61 years old failed to normalize calcemia either with conventional treatments (calcium 8 g/day + calcitriol 9 mcg/day and calcium 5 g/day + calcitriol 12 mcg/day) or with thrice daily subcutaneous injections of teriparatide. As a last resort, teriparatide infusion via Omnipod® device normalized their calcemia and allowed calcium/vitamin D withdrawal, with average teriparatide dose of 23 and 32 mcg/day, respectively. The flow of teriparatide was adapted according to a protocol based on measured calcemia, under medical supervision. In the literature, 15 adult cases (13 women, mean age 44.5 ± 5.2 years old) are reported. HypoPTH was consecutive to surgery in all of them. Mean dose of teriparatide administered was 25 ± 6 mcg/day with improvement of calcemia level and quality-of-life in all patients.

CONCLUSIONS

Continuous administration of teriparatide through Omnipod® appears as an efficient therapeutic option in refractory hypoPTH, whose administration to the patient can be assisted by medically-supervised protocol.

Teriparatide Therapy in a 4-Month-Old With Severe Hypoparathyroidism

Teriparatide is a human parathyroid hormone analog approved for the treatment of osteoporosis in adult patients. Its use for hypocalcemia and hypoparathyroidism in the pediatric population is described through case reports and small case series; however, larger studies that demonstrate long-term efficacy and safety are limited. At our institution, a 4-month-old premature (gestational age: 32 weeks) infant with multiple congenital anomalies, functional athymia, and severe hypoparathyroidism and receiving calcitriol, vitamin D, and calcium carbonate supplementation was initiated on subcutaneous injection of teriparatide. During the course of treatment, her calcium carbonate, vitamin D, and calcitriol supplementation requirements substantially decreased. Teriparatide effectively increased serum ionized calcium concentrations and decreased serum phosphorus concentrations in the present case-study over a 6-month period. Teriparatide was well tolerated, and no evidence of hypercalcemia was observed throughout treatment.

Continuous Teriparatide Treatment in Chronic Hypoparathyroidism: A Case Report

Patient: Female, 29-year-old

Final Diagnosis: Chronic hypoparathyroidism

Symptoms: Muscle cramps • numbness • tingling in fingers

Medication: —

Clinical Procedure: —

Specialty: Endocrinology and Metabolic

Therapy with PTH 1-34 or calcitriol and calcium in diverse etiologies of hypoparathyroidism over 27 years at a single tertiary care center

OBJECTIVE

Hypoparathyroidism has heterogeneous genetic and acquired etiologies with a broad spectrum of severity. Herein we describe the clinical outcomes of the largest cohort of hypoparathyroid patients reported to date, who were followed over 27-years.

DESIGN

Pooled analysis of current and past studies describing the differential responses to PTH 1-34 injections vs conventional therapy among the varied hypoPT etiologies.

METHODS

192 participants (ages 2-74 years) with hypoparathyroidism who received either calcitriol and calcium or PTH 1-34 by subcutaneous injection.

RESULTS

Among the 4 main etiologic categories of hypoparathyroidism (autoimmune polyglandular failure type 1, activating mutation of the calcium receptor, surgical, and idiopathic hypoparathyroidism), we reveal significant differences in PTH 1-34 dose requirements, prevalence of nephrocalcinosis, biomarkers of mineral homeostasis, and pharmacodynamic profiles. Serum 1,25-dihydroxyvitamin D₃ increased significantly (P < 0.001) and 25-hydroxyvitamin D levels decreased during PTH 1-34 injections compared to calcitriol therapy (P < 0.01). Post-surgical patients achieved consistently lower urine calcium excretion over long-term PTH 1-34 therapy compared to conventional therapy (p < 0.001), but this was not achieved in the other etiologies. At study entry, patients had a high prevalence of renal insufficiency and nephrocalcinosis which were directly related to the duration of hypoparathyroidism (P < 0.03). Renal function remained stable during participation in our studies for both PTH 1-34 and conventional therapies.

CONCLUSIONS

We conclude that the effects and dose-response of PTH 1-34 treatment differ according to the etiology of hypoparathyroidism. Postsurgical hypoPT maintained mean serum calcium levels in the mid- to low-normal range while concurrently maintaining normal mean urine calcium during long-term twice-daily PTH 1-34 therapy.

Safety and Efficacy of Oral Human Parathyroid Hormone (1-34) in Hypoparathyroidism: An Open-Label Study

The standard treatment of primary hypoparathyroidism (hypoPT) with oral calcium supplementation and calcitriol (or an analog), intended to control hypocalcemia and hyperphosphatemia and avoid hypercalciuria, remains challenging for both patients and clinicians. In 2015, human parathyroid hormone (hPTH) (1-84) administered as a daily subcutaneous injection was approved as an adjunctive treatment in patients who cannot be well controlled on the standard treatments alone. This open-label study aimed to assess the safety and efficacy of an oral hPTH(1-34) formulation as an adjunct to standard treatment in adult subjects with hypoparathyroidism. Oral hPTH(1-34) tablets (0.75 mg human hPTH(1-34) acetate) were administered four times daily for 16 consecutive weeks, and changes in calcium supplementation and alfacalcidol use, albumin-adjusted serum calcium (ACa), serum phosphate, urinary calcium excretion, and quality of life throughout the study were monitored. Of the 19 enrolled subjects, 15 completed the trial per protocol. A median 42% reduction from baseline in exogenous calcium dose was recorded (p = .001), whereas median serum ACa levels remained above the lower target ACa levels for hypoPT patients (>7.5 mg/dL) throughout the study. Median serum phosphate levels rapidly decreased (23%, p = .0003) 2 hours after the first dose and were maintained within the normal range for the duration of the study. A notable, but not statistically significant, median decrease (21%, p = .07) in 24-hour urine calcium excretion was observed between the first and last treatment days. Only four possible drug-related, non-serious adverse events were reported over the 16-week study, all by the same patient. A small but statistically significant increase from baseline quality of life (5%, p = .03) was reported by the end of the treatment period. Oral hPTH(1-34) treatment was generally safe and well tolerated and allowed for a reduction in exogenous calcium supplementation, while maintaining normocalcemia in adult patients with hypoparathyroidism. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Bone quality in hypoparathyroidism

Hypoparathyroidism is a rare disorder characterized by hypocalcemia and deficient or absent levels of parathyroid hormone. The consequences of chronic hypoparathyroidism involve classic target organs of parathyroid hormone, namely the skeleton and the kidneys. In this article, we focus on the abnormalities in bone quality that are associated with hypoparathyroidism. As assessed by several modalities, bone quality is compromised. The evidence for abnormal bone quality includes findings from bone histomorphometry, bone material properties, and high-resolution peripheral computed tomography. These abnormalities include low bone turnover, altered skeletal microarchitecture and bone material properties. How these abnormalities relate to fracture risk are under investigation. In this study, we also reviewed the therapeutic effects of parathyroid hormone as replacement therapy in this disease.

MANAGEMENT OF ENDOCRINE DISEASE: Postsurgical hypoparathyroidism: current treatments and future prospects for parathyroid allotransplantation

BACKGROUND

Permanent postsurgical hypoparathyroidism (POSH) is a major complication of anterior neck surgery in general and of thyroid surgery in particular. Depending on diagnostic criteria, up to 10% of patients undergoing bilateral thyroid surgery develop POSH. This leads to a multitude of symptoms that decrease the quality of life and burden the healthcare provision through complex needs for medication and treatment of specific complications, such as seizures and laryngospasm.

METHODS

Narrative review of current medical treatments for POSH and of the experience accumulated with parathyroid allotransplantation.

RESULTS

In most patients, POSH is controlled with regular use of calcium supplements and active vitamin D analogues but a significant proportion of patients continue to experience severe symptoms requiring repeated emergency admissions. Replacement therapy with synthetic PTH compounds (PTH1-34, Natpara® and PTH1-84, teriparatide, Forsteo®) has been assessed in multicentre trials, but the use of this medication is restricted by costs and concerns related to the risk of development of osteosarcoma. Based on recent case reports of successful allotransplantation of parathyroid tissue between siblings, there is renewed interest in this technique. Data on selection of donors, parathyroid cell preparation before allotransplantation, site and timing of transplantation, need for immunosuppression and long-term outcomes are reviewed.

CONCLUSION

A prospective trial to assess the efficacy of parathyroid allotransplantation in patients with severely symptomatic protracted post-surgical hypoparathyroidism is warranted.

Chronic hypoparathyroidism and treatment with teriparatide

PURPOSE

Chronic hypoparathyroidism is usually treated with calcium and active vitamin D metabolites or analogs, despite the fact that their chronic use can lead to long-term complications. The use of hormone replacement therapy with PTH peptides [teriparatide and rhPTH (1-84)] has therefore been proposed. The main purpose of this study was to investigate the efficacy of teriparatide dose at 20 µg once or twice daily, in order to maintain normocalcemia reducing standard treatment, in adult patients with chronic hypoparathyroidism not well controlled with conventional treatment.

METHODS

The study was a Phase III, open-label, non-comparative, clinical investigation (study period: 3 months), at a tertiary care clinical research center. Thirty patients with chronic hypoparathyroidism were screened, and 12 started teriparatide. After the optimization phase (0-4 weeks), calcium and calcitriol supplements were progressively reduced, while teriparatide 20 µg once daily was administered (5-7 weeks), and then could be titrated up to 20 µg twice daily (7-17 weeks). The main outcome measures included serum and urinary biochemical exams and Rand 36-Item Short Form Health Survey.

RESULTS

This study showed that teriparatide 20 µg once daily was insufficient to discontinue calcium and calcitriol supplements to maintain normal serum calcium concentrations. Conversely, for more than half of patients treated with teriparatide 20 µg twice daily, calcium and calcitriol administration was avoidable, but in some cases at the expense of serum calcium and phosphate oscillations.

CONCLUSIONS

Since intervention trials evaluating the efficacy and safety of teriparatide in hypoparathyroid patients are not yet available, the routine use of this molecule poses some doubts.

Impact of periprocedural subcutaneous parathyroid hormone on control of hypocalcaemia in APS-1/APECED patients undergoing invasive procedures

CONTEXT

The monogenic disorder autoimmune polyendocrine syndrome type 1 (APS-1) or autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) manifests frequently with hypoparathyroidism, which requires treatment with oral supplementation with calcium and active vitamin D analogs. The majority of APS-1/APECED patients also suffer from intestinal malabsorption, which complicates the management of hypoparathyroidism and may lead to refractory severe hypocalcaemia. In such situations, reliance on intravenous calcium carries a high risk of nephrocalcinosis and renal damage.

METHODS

Here, we report our experience of periprocedural subcutaneous administration of recombinant human parathyroid hormone (rhPTH 1-34) in APS-1/APECED patients. Serum calcium was measured up to five times within the 36-hour period starting the evening before the scheduled procedure and ending the morning following the procedure.

RESULTS

Twenty-seven APS-1/APECED patients with hypoparathyroidism (aged 4-67 years) underwent 31 invasive gastrointestinal and/or pulmonary procedures. The patients received an average rhPTH1-34 dose of 9.6 ± 1.4 µg by subcutaneous injection. 92% of the adults and 54% of children in our cohort had evidence of nephrocalcinosis. Mean calcium levels remained stable and ranged from 2.06 to 2.17 mmol/L with minimal fluctuation. None of our patients experienced periprocedural adverse events connected with hypocalcaemia.

CONCLUSION

rhPTH 1-34 is an alternative to conventional therapy in patients with APS-1/APECED and hypoparathyroidism undergoing invasive procedures. Subcutaneous PTH1-34 given directly before and after procedures resulted in well-controlled serum calcium levels maintained in the low-normal range and avoided the need for intravenous calcium which may contribute to renal calcifications and tubular damage.

Intermittent Bi-Daily Sub-cutaneous Teriparatide Administration in Children With Hypoparathyroidism: A Single-Center Experience

Introduction: The use of teriparatide has been reported in children with hypoparathyroidism as an investigational physiologic replacement therapy. Methods: We aimed to retrospectively report our pediatric experience of bi-daily sub-cutaneous teriparatide. Results are presented as median (25th-75th quartile). As part of the routine follow-up of these patients with hypoparathyroidism, total calcium at H0 (i.e., just before injection) and H4 (i.e., 4 h after teriparatide injection) and other biomarker parameters were regularly assessed. Results: At a median age of 10.7 (8.1-12.6) years, an estimated glomerular filtration rate (eGFR) of 110 (95-118) mL/min/1.73 m², calcium levels of 1.87 (1.81-1.96) mmol/L and an age-standardized phosphate of 3.8 (2.5-4.9) SDS, teriparatide therapy was introduced in 10 patients at the dose of 1.1 (0.7-1.5) μg/kg/day (20 μg twice daily), with further adjustment depending on calcium levels. Six patients already displayed nephrocalcinosis. Severe side effects were reported in one child: two episodes of symptomatic hypocalcemia and one of iatrogenic hypercalcemia; one teenager displayed dysgueusia. Calcium levels at H0 did not significantly increase whilst calcium at H4 and phosphate levels significantly increased and decreased, respectively. After 12 months, eGFR, calcium and age-standardized phosphate levels were 108 (90-122) mL/min/1.73 m², 2.36 (2.23-2.48) mmol/L, 0.5 (-0.1 to 1.5), and 68 (63-74) nmol/L, respectively, with a significant decrease in phosphate levels (p = 0.01). Urinary calcium and calcium/creatinine ratio remained stable; no nephrolithiasis was observed but two moderate nephrocalcinosis appeared. Conclusion: Intermittent teriparatide therapy significantly improves calcium and phosphate control, without increasing calciuria. It appears to be safe and well-tolerated in children.

Diagnosis and management of hypocalcemia

The aim of this clinical narrative review is to summarize and critically appraise the literature on the differential diagnosis of hypocalcemia and to provide its correct management. Calcium is essential for muscle contraction and neurotransmitter release, but clinical manifestations of hypocalcaemia (serum calcium level <8 mg/dl; 2.12 mmol/L) may involve almost any organ and system and may range from asymptomatic to life-threating conditions. Disorders causing hypocalcemia can be divided into parathyroid hormone (PTH) and non-PTH mediated. The most frequent cause of hypocalcemia is postsurgical hypoparathyroidism, while a more comprehensive search for other causes is needed for appropriate treatment in the non PTH-mediated forms. Intravenous calcium infusion is essential to raise calcium levels and resolve or minimize symptoms in the setting of acute hypocalcemia. Oral calcium and/or vitamin D supplementation is the most frequently used as treatment of chronic hypocalcemia. In hypoparathyroidism, providing the missing hormone with the use of the recombinant human (rh) PTH(1-84) has been recently approved both by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This new therapy has the advantage of being effective for correcting serum calcium levels and significantly reducing the daily requirements of calcium and active vitamin D supplements. However, due to the high cost, a strict selection of candidates to this therapy is necessary. More challenging is the long-term hypocalcemia treatment, due to its associated complications. The development of long-acting recombinant human PTH will probably modify the management of chronic hypoparathyroidism in the future.

Recent advances in understanding and managing hypoparathyroidism

Hypoparathyroidism is a rare endocrine disorder which leads to hypocalcemia, hypercalciuria, and hyperphosphatemia. Complications include nephrocalcinosis with renal dysfunction, reduced quality of life, and abnormal skeletal properties. Conventional therapy with calcium and vitamin D analogs addresses hypocalcemia but has important limitations. Parathyroid hormone (PTH) therapy is a fundamental advance, although the effects of PTH on long-term complications require additional testing. Continuous PTH therapy is likely to be particularly advantageous for addressing renal, quality of life, and skeletal complications. Overall, much progress has been made, yet more information is needed to improve our understanding and management of hypoparathyroidism.

Children are at a high risk of hypocalcaemia and hypoparathyroidism after total thyroidectomy

PURPOSE

Disruption of calcium homeostasis is the most common complication after total thyroidectomy in adults. We explored the incidence and risk factors of hypocalcaemia and hypoparathyroidism after total thyroidectomy in children (≤18 years of age).

METHODS

One hundred six children underwent total thyroidectomy. Patient, operative and outcome data were collected and analyzed.

RESULTS

The indication for surgery was Graves' disease in 52 children (49.1%), Multiple Endocrine Neoplasia type-2 in 36 (33.9%), multinodular goiter in 3 (2.8%) and follicular/papillary thyroid carcinoma in 15 (14.2%). Neck dissection was performed in 23 children (18.9%). In 14 children (13.2%), autotransplantation was performed; in 31 (29.2%), ≥1 glands were found in the specimen. Hypocalcaemia within 24 h of thyroidectomy was observed in 63 children (59.4%) and 52 (49.3%) were discharged on supplements. Hypoparathyroidism at 6 months persisted in 23 children (21.7%). The ratios of all forms of calcium-related-morbidity were larger among children with less than four parathyroid glands remaining in situ: hypocalcaemia within 24 h of thyroidectomy (54.0% versus 47.5%; p = 0.01), hypoparathyroidism on discharge (64.4% versus 37.7%; p = 0.004) and long-term hypoparathyroidism (31.1% versus 14.8%; p = 0.04).

CONCLUSION

The incidence of postoperative hypocalcaemia and hypoparathyroidism among children undergoing total thyroidectomy is considerable. The inability to preserve the parathyroid glands in situ during surgery seems an important factor. For optimal outcomes, the parathyroid glands should be preserved in situ.

TYPE OF STUDY

Prognosis Study.

LEVEL OF EVIDENCE

Level IV.

Hypoparathyroidism

BACKGROUND

Hypoparathyroidism is a rare endocrine disorder characterized by hypocalcemia and low or undetectable levels of parathyroid hormone.

METHODS

This review is an evidence-based summary of hypoparathyroidism in terms of relevant pathophysiological, clinical, and therapeutic concepts.

RESULTS

Many clinical manifestations of hypoparathyroidism are due to the lack of the physiological actions of parathyroid hormone on its 2 major target organs: the skeleton and the kidney. The skeleton is inactive, accruing bone without remodeling it. The kidneys lose the calcium-conserving actions of parathyroid hormone and, thus, excrete a greater fraction of calcium. Biochemical manifestations, besides hypocalcemia and low or undetectable levels of parathyroid hormone, include hyperphosphatemia and low levels of 1,25-dihydroxyvitamin D. Calcifications in the kidney, brain, and other soft tissues are common. Removal of, or damage to, the parathyroid glands at the time of anterior neck surgery is, by far, the most likely etiology. Autoimmune destruction of the parathyroid glands and other genetic causes represent most of the other etiologies. Conventional treatment with calcium and active vitamin D can maintain the serum calcium level but high doses may be required, adding to the risk of long-term soft tissue calcifications. The advent of replacement therapy with recombinant human PTH(1-84) represents a major step in the therapeutics of this disease.

CONCLUSIONS

Advances in our knowledge of hypoparathyroidism have led to greater understanding of the disease itself and our approach to it.

Parathyroid Hormone Replacement versus Oral Calcium and Active Vitamin D Supplementation in Hypoparathyroidism: A Meta-analysis

OBJECTIVES

Chronic hypoparathyroidism is treated conventionally with active vitamin D and high doses of calcium. Recombinant human parathyroid hormone (PTH) replacement is an attractive option for treating patients with hypoparathyroidism since it can replace the physiological action of native PTH. The aim of our study was to perform a comprehensive evaluation of the effects of PTH replacement on calcium homeostasis, bone metabolism, and daily requirement of calcium and active vitamin D.

MATERIALS AND METHODS

Randomized controlled trials done in chronic hypoparathyroid patients were included in this meta-analysis. The PTH group included subjects receiving a subcutaneous injection of either PTH (1-84) or PTH (1-34) with oral calcium and/or active vitamin D. The control group included those receiving oral calcium and active vitamin D with/without subcutaneous placebo injection. The primary outcome of this meta-analysis was to compare serum calcium, 24-h urinary calcium, and severe adverse effects among PTH and control groups.

RESULTS

In this meta-analysis, we did not find any difference in serum calcium level between PTH and control groups [mean difference (MD) - 0.01; 95% confidence interval (CI) - 0.09, 0.06; P = 0.71]. Although there was a trend towards low 24-h urinary calcium in the PTH group, the difference was not statistically significant (MD - 1.43; 95% CI - 2.89, 0.03; P = 0.06). The incidence of serious adverse events was also similar in both groups (RR 1.35; 95% CI 0.58, 3.16; P = 0.49).

CONCLUSION

Both PTH and active vitamin D therapies are associated with comparable serum and urine calcium levels with a similar incidence of serious adverse events in patients with chronic hypoparathyroidism.

Teriparatide (rhPTH 1-34) treatment in the pediatric age: long-term efficacy and safety data in a cohort with genetic hypoparathyroidism

BACKGROUND

Hypoparathyroidism is characterized by the absence or inadequately low circulating concentrations of the parathyroid hormone, resulting in hypocalcemia, hyperphosphatemia, and elevated fractional excretion of calcium in the urine. The use of activated vitamin D analogs and calcium supplements represent conventional therapy. Subcutaneous recombinant human parathormone [rhPTH(1-34)] has been proposed as a substitutive treatment, even to avoid side effects of vitamin D and calcium.

OBJECTIVE

To assess the long-term safety and efficacy of rhPTH(1-34) in a pediatric cohort of patients with genetic hypoparathyroidism.

METHODS

The study is a 9.2-year self-controlled study of six pediatric patients (four males and two females, aged 9.4 ± 5.2) with DiGeorge, hypoparathyroidism-deafness-renal dysplasia (HDR) or autoimmune-candidiasis-polyendocrinopathy-ectodermal-dysplasia (APECED) syndrome, associated with autoimmune intestinal malabsorption in a patient. The presence of clinical signs of hypocalcemia and biochemical parameters, such as calcium, phosphate, alkaline phosphatase in the blood and calcium-creatinine ratio in urine, were compared during conventional treatment and rhPTH(1-34) (teriparatide, 12.5 μg twice daily).

RESULTS

The rhPTH(1-34) treatment allowed a reduction, although not always a complete suspension, of calcium supplementation and a slight reduction of calcitriol therapy. The number of tetanic episodes was reduced in four patients during the rhPTH(1-34) treatment. Mean blood calcium, alkaline phosphatase, and phosphate did not significantly change, while a significant reduction of the urinary calcium-to-creatinine ratio (0.55 ± 0.32 vs 0.16 ± 0.09, p = 0.03) was obtained. Renal ultrasound examination showed a worsening in three patients, while it did not change in the remaining three subjects during the follow-up.

CONCLUSIONS

In children with syndromic hypoparathyroidism presented here, replacement therapy with rhPTH(1-34) allowed to maintain adequate levels of the calcium and phosphate in the blood, normalize urinary calcium excretion, and reduce tetanic episodes. In patients with low compliance to conventional therapy or intestinal malabsorption, the use of rhPTH(1-34) could be considered, also to reduce the side effects of treatment with vitamin D and calcium.

Current status in therapeutic interventions of neonatal bone mineral metabolic disorders

Neonatal care has significantly improved in the past decade with improved survival of preterm and sick neonates. Similarly, the field of bone and mineral disorders is continuing to accelerate with better understanding of pathophysiology and genetic basis of diseases, as well as availability of newer diagnostic and therapeutic modalities. In this extensive and rapidly expanding field, metabolic bone disease specialists are frequently called upon to translate progress into better care for neonates with bone and mineral disorders. Accordingly, this chapter provides a review of clinical manifestations and evidence-based investigation and management (where available) of common, rare and ultra-rare disorders of bone and mineral metabolism manifesting in the neonatal period. Besides medical treatment we emphasise the crucial role of the multidisciplinary team, which include physical therapists, occupational therapists and dieticians, in the care of neonates with bone disorders such as osteogenesis imperfecta and achondroplasia.

Hypoparathyroidism with Fahr’s syndrome: A case report and review of the literature

BACKGROUND

Hypoparathyroidism with basal ganglia calcification is clinically rare. Here, we report a case of Fahr’s syndrome due to hypoparathyroidism and review the literature in terms of etiology, clinical manifestation, diagnosis, and treatment.

CASE SUMMARY

A 62-year-old man experienced repeated twitching of both hands in recent 10 years. On July 28, 2017, the patient was admitted to our hospital due to slow response and speech difficulties. On medical examinations, he had a positive Chvostek sign, while no Albright’s hereditary osteodystrophy signs or history of neck surgery or radiation, and his family members had no similar medical history. Laboratory examinations revealed hypocalcemia, hyperphosphatemia, and low parathyroid hormone (PTH) levels. Computed tomography revealed basal ganglia calcification. Based on these investigations, a diagnosis of Fahr’s syndrome due to hypoparathyroidism was suggested. After receiving intravenous calcium gluconate to relieve symptoms, the patient continued to take oral calcium carbonate and calcitriol for treatment.

CONCLUSION

The possibility of hypoparathyroidism should be considered in patients with chronic hypocalcemia, recurrent tetany, and even neuropsychiatric symptoms. Hypoparathyroidism is a common cause of basal ganglia calcification. Therefore, it is recommended that blood calcium, phosphorus, and PTH levels should be measured in all individuals with basal ganglia calcification to exclude hypoparathyroidism.

Calcium, vitamin D or recombinant parathyroid hormone for managing post-thyroidectomy hypoparathyroidism

BACKGROUND

Post-surgical hypoparathyroidism is a common complication after thyroid surgery. The incidence is likely to increase given the rising trend in the annual number of thyroid operations being performed. Measures to prevent post-thyroidectomy hypoparathyroidism including different surgical techniques and prophylactic calcium and vitamin D supplements have been extensively studied. The management of post-thyroidectomy hypoparathyroidism however has not been extensively evaluated. Routine use of calcium and vitamin D supplements in the postoperative period may reduce the risk of symptoms, temporary hypocalcaemia and hospital stay. However, this may lead to overtreatment and has no effect on long-term hypoparathyroidism. Current recommendations on the management of post-thyroidectomy hypoparathyroidism is based on low-quality evidence. Existing guidelines do not often distinguish between surgical and non-surgical hypoparathyroidism, and transient and long-term disease.The aim of this systematic review was to summarise evidence on the use of calcium, vitamin D and recombinant parathyroid hormone in the management of post-thyroidectomy hypoparathyroidism. In addition, we aimed to highlight deficiencies in the current literature and stimulate further work in this field.

OBJECTIVES

The objective of this systematic review was to assess the effects of calcium, vitamin D and recombinant parathyroid hormone in managing post-thyroidectomy hypoparathyroidism.

SEARCH METHODS

We searched CENTRAL, MEDLINE, PubMed, Embase as well as ICTRP Search Portal and ClinicalTrials.gov. The date of the last search for all databases was 17 December 2018 (except Embase, which was last searched on 21 December 2017). No language restrictions were applied.

SELECTION CRITERIA

We planned to include randomised control trials (RCTs) or controlled clinical trials (CCTs) examining the effects of calcium, vitamin D or recombinant parathyroid hormone in people with temporary and long-term post-thyroidectomy hypoparathyroidism.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles, abstracts and full texts for relevance.

MAIN RESULTS

Database searches yielded a total of 1751 records. We retrieved potentially relevant full texts and excluded articles on the following basis: not a RCT or CCT; intervention, comparator or both did not match prespecified criteria; non-surgical causes of hypoparathyroidism, and studies on prevention. None of the articles was eligible for inclusion in the systematic review.

AUTHORS' CONCLUSIONS

This systematic review highlights a gap in the current literature and the lack of high-quality evidence in the management of post-thyroidectomy temporary and long-term hypoparathyroidism. Further research focusing on clinically relevant outcomes is needed to examine the effects of current treatments in the management of temporary and long-term post-thyroidectomy hypocalcaemia.

Hypoparathyroidism: is it that easy to treat?

Hypoparathyroidism is a relatively rare endocrine disease characterised by either null or inappropriately low secretion of parathyroid hormone (PTH) for serum calcium levels. The other main laboratory findings include hypocalcaemia, inappropriately normal or high urine calcium excretion and hyperphosphataemia with low urine phosphate excretion. The management of hypoparathyroidism should be tailored to each individual case, which makes it a demanding undertaking in everyday clinical practice. In this review, we sought to focus on the diagnostic approach of hypoparathyroidism and the therapeutic challenges of the disease from a clinical perspective. Conventional treatment with vitamin D analogues and calcium salts is no longer the only available treatment, since replacement treatment with PTH(1-84) has recently been approved for the disease. However, the optimal treatment schedule is yet to be defined.

Advances in the treatment of hypoparathyroidism with PTH 1-34

Hypoparathyroidism is a rare disorder of calcium metabolism which is treated with calcium and vitamin D analogs. Although conventional therapy effectively raises serum calcium, it bypasses the potent calcium reabsorption effects of PTH on the kidney which leads to hypercalciuria and an increased risk of nephrocalcinosis and renal insufficiency. Twenty-five years ago, we launched the first systematic investigation into synthetic human PTH 1-34 replacement therapy in both adults and children. These studies led to our current understanding of the complex nature of PTH 1-34 therapy and to the challenges we still face in our pursuit of a safe and effective physiologic replacement therapy for hypoparathyroidism. The normalization and minimal fluctuation of serum and urine calcium levels were the primary management goals. As the frequency of PTH 1-34 injections increased, the total daily dose required to normalize calcium homeostasis decreased and episodes of hypercalcemia and hypercalciuria diminished, producing a more physiologic biochemical profile. Twice-daily injections achieved simultaneous normalization of serum and urine calcium levels in many patients but the persistent elevation of bone markers and the difficulty in reducing urine calcium to normal levels in the more severe cases, suggested an alternative to PTH 1-34 injections was needed. The studies with PTH 1-34 delivered by insulin pump represent an important advance in the management of hypoparathyroidism. PTH 1-34 delivered by insulin pump normalized serum and urine calcium and markers of bone turnover. Additionally, pump delivery of PTH 1-34 produced stable magnesium values within the normal range and reduced magnesium excretion. Currently, PTH 1-34 delivery by pump is the only alternative to PTH injections that has been tested in both adults and children and proven to achieve a physiologic biochemical profile.

Skeletal Manifestations of Hypoparathyroidism

Chronic PTH deficiency has a marked effect on the skeleton, leading to characteristic decreases in bone remodeling and increases in bone mass. An effect on fracture risk has not been demonstrated, although biochemical, imaging, and histomorphometric data indicate abnormalities in skeletal properties^1,21,21,21,2. Replacement with PTH leads to a new skeletal state that is maintained with long-term treatment.

Standards of care for hypoparathyroidism in adults: a Canadian and International Consensus

PURPOSE

To provide practice recommendations for the diagnosis and management of hypoparathyroidism in adults.

METHODS

Key questions pertaining to the diagnosis and management of hypoparathyroidism were addressed following a literature review. We searched PubMed, MEDLINE, EMBASE and Cochrane databases from January 2000 to March 2018 using keywords 'hypoparathyroidism, diagnosis, treatment, calcium, PTH, calcidiol, calcitriol, hydrochlorothiazide and pregnancy'. Only English language papers involving humans were included. We excluded letters, reviews and editorials. The quality of evidence was evaluated based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. These standards of care for hypoparathyroidism have been endorsed by the Canadian Society of Endocrinology and Metabolism.

RESULTS

Hypoparathyroidism is a rare disease characterized by hypocalcemia, hyperphosphatemia and a low or inappropriately normal serum parathyroid hormone level (PTH). The majority of cases are post-surgical (75%) with nonsurgical causes accounting for the remaining 25% of cases. A careful review is required to determine the etiology of the hypoparathyroidism in individuals with nonsurgical disease. Hypoparathyroidism is associated with significant morbidity and poor quality of life. Treatment requires close monitoring as well as patient education. Conventional therapy with calcium supplements and active vitamin D analogs is effective in improving serum calcium as well as in controlling the symptoms of hypocalcemia. PTH replacement is of value in lowering the doses of calcium and active vitamin D analogs required and may be of value in lowering long-term complications of hypoparathyroidism. This manuscript addresses acute and chronic management of hypoparathyroidism in adults.

MAIN CONCLUSIONS

Hypoparathyroidism requires careful evaluation and pharmacologic intervention in order to improve serum calcium and control the symptoms of hypocalcemia. Frequent laboratory monitoring of the biochemical profile and patient education is essential to achieving optimal control of serum calcium.

Long-Term Parathyroid Hormone 1-34 Replacement Therapy in Children with Hypoparathyroidism

OBJECTIVE

To determine whether multiple daily injections of parathyroid hormone (PTH) 1-34 are safe and effective as long-term therapy for children with hypoparathyroidism.

STUDY DESIGN

Linear growth, bone accrual, renal function, and mineral homeostasis were studied in a long-term observational study of PTH 1-34 injection therapy in 14 children.

METHODS

Subjects were 14 children with hypoparathyroidism attributable to autoimmune polyglandular syndrome type 1 (N = 5, ages 7-12 years) or calcium receptor mutation (N = 9, ages 7-16 years). Mean daily PTH 1-34 dose was 0.75 ± 0.15 µg/kg/day. Treatment duration was 6.9 ± 3.1 years (range 1.5-10 years). Patients were evaluated semiannually at the National Institutes of Health Clinical Center.

RESULTS

Mean height velocity and lumbar spine, whole body, and femoral neck bone accretion velocities were normal throughout the study. In the first 2 years, distal one-third radius bone accrual velocity was reduced compared with normal children (P < .003). Serum alkaline phosphatase correlated with PTH 1-34 dose (P < .006) and remained normal (235.3 ± 104.8 [SD] U/L, N: 51-332 U/L). Mean serum and 24-hour urine calcium levels were 2.05 ± 0.11 mmol/L (N: 2.05-2.5 mmol/L) and 6.93 ± 1.3 mmol/24 hour (N: 1.25-7.5 mmol/24 hour), respectively-with fewer high urine calcium levels vs baseline during calcitriol and calcium treatment (P < .001). Nephrocalcinosis progressed in 5 of 12 subjects who had repeated renal imaging although renal function remained normal.

CONCLUSIONS

Twice-daily or thrice-daily subcutaneous PTH 1-34 injections provided safe and effective replacement therapy for up to 10 years in children with hypoparathyroidism because of autoimmune polyglandular syndrome type 1 or calcium receptor mutation.

Hypoparathyroidism and the Kidney

Hypocalcemia and hyperphosphatemia are the pathognomonic biochemical features of hypoparathyroidism, and result directly from lack of parathyroid hormone (PTH) action on the kidney. In the absence of PTH action, the renal mechanisms transporting calcium and phosphate reabsorption deregulate, resulting in hypocalcemia and hyperphosphatemia. Circulating calcium negatively regulates PTH secretion. Hypocalcemia causes neuromuscular disturbances ranging from epilepsy and tetany to mild paresthesia. Circulating phosphate concentration does not directly regulate PTH secretion. Hyperphosphatemia is subclinical, but chronically promotes ectopic mineralization disease. Vitamin D-thiazide treatment leads to ectopic mineralization and renal damage. PTH treatment has the potential for fewer side effects.

Skeletal Manifestations of Hypoparathyroidism

Chronic parathyroid hormone (PTH) deficiency has a marked effect on the skeleton, leading to characteristic decreases in bone remodeling and increases in bone mass. Numerous lines of evidence using biochemical, imaging, and histomorphometric methodologies have demonstrated that the skeleton is altered when PTH is absent and that these abnormalities might be reversed with PTH treatment. More evidence is needed to determine whether fracture risk is altered in hypoparathyroidism.

New Directions in Treatment of Hypoparathyroidism

The history of parathyroid hormone (PTH) replacement therapy for hypoparathyroidism begins in 1929. In 2015, the Food and Drug Administration approved recombinant human PTH(1-84) [rhPTH(1-84)] as a treatment for hypoparathyroidism. Long-term studies of rhPTH(1-84), up to 6 years, have demonstrated continued efficacy of this replacement agent. Approaches to optimize PTH treatment in hypoparathyroidism include subcutaneous pump delivery systems, long-lived carrier molecules, and long-acting PTH analogues that show promise to prolong efficacy. Calcilytic compounds have been explored as a treatment for autosomal dominant hypocalcemia. Calcilytics are negative modulators of the calcium-sensing receptor and may present a therapeutic opportunity to increase endogenous PTH synthesis and secretion.

Clinical presentation and management of hypoparathyroidism

The clinical manifestations of hypoparathyroidism are variable and can involve almost any organ system. The main clinical features of the hypoparathyroidism are typically signs or symptoms due to neuromuscular irritability owing to low serum calcium level. In addition to hypocalcemia, hyperphosphatemia can contribute to long-term complications, including extra-skeletal calcifications. Bone turnover markers are generally decreased, and bone mass density is usually normal-increased compared to age- and gender-matched controls. It is still unclear whether or not these bone features could have an impact on the risk of fracture. Impaired renal function is a common complication described in patients treated for hypoparathyroidism. Other complications include premature cataracts, seizures, basal ganglia calcifications, and cardiac arrhythmias. Lastly, some clinical studies have also reported a reduced quality of life of patients with hypoparathyroidism. Increased awareness of the clinical manifestations of this disease is important to improve its clinical management.

Optimal dosing and delivery of parathyroid hormone and its analogues for osteoporosis and hypoparathyroidism - translating the pharmacology

In primary hyperparathyroidism (PHPT), bone loss results from the resorptive effects of excess parathyroid hormone (PTH). Under physiological conditions, PTH has actions that are more targeted to homeostasis and to bone accrual. The predominant action of PTH, either catabolic, anabolic or homeostatic, can be understood in molecular and pharmacokinetic terms. When administered intermittently, PTH increases bone mass, but when present continuously and in excess (e.g. PHPT), bone loss ensues. This dual effect of PTH depends not only on the dosing regimen, continuous or intermittent, but also on how the PTH molecule interacts with various states of its receptor (PTH/PTHrP receptor) influencing downstream signalling pathways differentially. Altering the amino-terminal end of PTH or PTHrP could emphasize the state of the receptor that is linked to an osteoanabolic outcome. This concept led to the development of a PTHrP analogue that interacts preferentially with the transiently linked state of the receptor, emphasizing an osteoanabolic effect. However, designing PTH or PTHrP analogues with prolonged state of binding to the receptor would be expected to be linked to a homeostatic action associated with the tonic secretory state of the parathyroid glands that is advantageous in treating hypoparathyroidism. Ideally, further development of a drug delivery system that mimics the physiological tonic, circadian, and pulsatile profile of PTH would be optimal. This review discusses basic, translational and clinical studies that may well lead to newer approaches to the treatment of osteoporosis as well as to different PTH molecules that could become more advantageous in treating hypoparathyroidism.

Developments in rare bone diseases and mineral disorders

In the last decade, there have been a number of significant advances made in the field of rare bone diseases. In this review, we discuss the expansion of the classification system for osteogenesis imperfecta (OI) and the resultant increase in therapeutic options available for management of OI. Bisphosphonates remain the most widely used intervention for OI, although the effect on fracture rate reduction is equivocal. We review the other therapies showing promising results, including denosumab, teriparatide, sclerostin, transforming growth factor β inhibition and gene targeted approaches. X-linked hypophosphataemia (XLH) is the most common heritable form of osteomalacia and rickets caused by a mutation in the phosphate regulating endopeptidase gene resulting in elevated serum fibroblast growth factor 23 (FGF23) and decreased renal phosphate reabsorption. The traditional treatment is phosphate replacement. We discuss the development of a human anti-FGF23 antibody (KRN23) as a promising development in the treatment of XLH. The current management of primary hypoparathyroidism is replacement with calcium and active vitamin D. This can be associated with under or over replacement and its inherent complications. We review the use of recombinant parathyroid hormone (1-84), which can significantly reduce the requirements for calcium and vitamin D resulting in greater safety and quality of life for individuals with hypoparathyroidism. The use of receptor activator of nuclear factor κB ligand infusions in the treatment of a particular form of osteopetrosis and enzyme replacement therapy for hypophosphatasia are also discussed.

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

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

PTH(1-34) for Surgical Hypoparathyroidism: A 2-Year Prospective, Open-Label Investigation of Efficacy and Quality of Life

CONTEXT

Daily parathyroid hormone (PTH) (1-34) administrations can reduce the required total daily dose of calcium and calcitriol and restore normocalcemia in refractory hypoparathyroidism. However, most PTH(1-34) trials have been conducted on small cohorts including subjects with hypoparathyroidism of various etiologies, and quality of life (QOL) was not investigated.

OBJECTIVE

To investigate the effects of 24-month PTH(1-34) treatment in a homogeneous cohort of adult subjects with postoperative hypoparathyroidism and to evaluate QOL changes.

DESIGN

Prospective open-label study.

SETTING

Italian multicenter study.

PARTICIPANTS

42 subjects.

INTERVENTION

Twice-daily PTH(1-34) 20 μg subcutaneous injection.

MAIN OUTCOME MEASURES

Calcium and vitamin D supplementation requirements, serum calcium, phosphate, and urinary calcium excretion (3, 6, 12, 18, 24 months). At baseline and at 6 and 24 months, QOL was evaluated by the RAND 36-Item Short Form (SF-36) Health Survey, covering eight domains of physical and mental health.

RESULTS

Mean serum calcium concentration significantly increased from baseline to 3 months (7.6 ± 0.6 vs 8.9 ± 1.1 mg/dL, P < 0.001) and remained stable until the end of the study, despite reductions in calcium and vitamin D supplementation. Phosphate levels gradually decreased from baseline to 6 months (4.3 ± 1.1 vs 3.9 ± 0.6 mg/dL, P < 0.019), remaining stable until 24 months. Serum alkaline phosphatase and calcium excretion gradually increased from baseline to 24 months. Data from SF-36 showed a significant improvement in the mean scores of all eight domains (P < 0.001).

CONCLUSION

This study demonstrates the efficacy and safety of PTH(1-34) to treat adult patients with postsurgical hypoparathyroidism. PTH(1-34) may improve their mental and physical health.

Repurposing a novel parathyroid hormone analogue to treat hypoparathyroidism

BACKGROUND AND PURPOSE

Human parathyroid hormone (PTH) is critical for maintaining physiological calcium homeostasis and plays an important role in the formation and maintenance of the bone. Full-length PTH and a truncated peptide form are approved for treatment of hypoparathyroidism and osteoporosis respectively. Our initial goal was to develop an improved PTH therapy for osteoporosis, but clinical development was halted. The novel compound was then repurposed as an improved therapy for hypoparathyroidism.

EXPERIMENTAL APPROACH

A longer-acting form of PTH was synthesised by altering the peptide to increase cell surface residence time of the bound ligand to its receptor. In vitro screening identified a compound, which was tested in an animal model of osteoporosis before entering human trials. This compound was subsequently tested in two independent animal models of hypoparathyroidism.

KEY RESULTS

The peptide identified, LY627-2K, exhibited delayed internalization kinetics. In an ovariectomy-induced bone loss rat model, LY627-2K demonstrated improved vertebral bone mineral density and biomechanical properties at skeletal sites and a modest increase in serum calcium. In a Phase I clinical study, dose-dependent increases in serum calcium were reproduced. These observations prompted us to explore a second indication, hypoparathyroidism. In animal models of this disease, LY627-2K restored serum calcium, comparing favourably to treatment with wild-type PTH.

CONCLUSIONS AND IMPLICATIONS

We summarize the repositioning of a therapeutic candidate with substantial preclinical and clinical data. Our results support its repurposing and continued development, from a common indication (osteoporosis) to a rare disease (hypoparathyroidism) by exploiting a shared molecular target.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Impact of intercurrent illness on calcium homeostasis in children with hypoparathyroidism: a case series

BACKGROUND

Hypoparathyroidism is characterised by hypocalcaemia, and standard management is with an active vitamin D analogue and adequate oral calcium intake (dietary and/or supplements). Little is described in the literature about the impact of intercurrent illnesses on calcium homeostasis in children with hypoparathyroidism.

METHODS

We describe three children with hypoparathyroidism in whom intercurrent illnesses led to hypocalcaemia and escalation of treatment with alfacalcidol (1-hydroxycholecalciferol) and calcium supplements.

RESULTS

Three infants managed with standard treatment for hypoparathyroidism (two with homozygous mutations in GCMB2 gene and one with Sanjad-Sakati syndrome) developed symptomatic hypocalcaemia (two infants developed seizures) following respiratory or gastrointestinal illnesses. Substantial increases in alfacalcidol doses (up to three times their pre-illness doses) and calcium supplementation were required to achieve acceptable serum calcium concentrations. However, following resolution of illness, these children developed an increase in serum calcium and hypercalciuria, necessitating rapid reduction to pre-illness dosages of alfacalcidol and oral calcium supplementation.

CONCLUSION

Intercurrent illness may precipitate symptomatic hypocalcaemia in children with hypoparathyroidism, necessitating increase in dosages of alfacalcidol and calcium supplements. Close monitoring is required on resolution of the intercurrent illness, with timely reduction of dosages of active analogues of vitamin D and calcium supplements to prevent hypercalcaemia, hypercalciuria and nephrocalcinosis.

Hypoparathyroidism: disease update and new methods of treatment

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

Hypoparathyroidism

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

Efficacy of Teriparatide in Patients with Hypoparathyroidism: A Prospective, Open-label Study

CONTEXT

Conventional treatment of hypoparathyroidism with calcium, Vitamin D analogs, and thiazide diuretics is often suboptimal, and these patients have poor quality of life. Teriparatide (parathyroid hormone 1-34 [PTH (1-34)]), an amide of PTH, is widely available for the use in osteoporosis; however, its use in hypoparathyroidism is limited.

AIMS

The aim of this study is to evaluate the efficacy of PTH (1-34) in the treatment of patients with hypoparathyroidism.

SETTINGS AND DESIGN

This was a prospective, open-label interventional study in a tertiary care hospital of Indian Armed Forces.

SUBJECTS AND METHODS

All patients with hypoparathyroidism presented to the endocrinology outpatient department were included and were exhibited injection PTH (1-34) 20 μg twice daily that was gradually reduced to 10 μg twice daily along with calcium, active Vitamin D (alfacalcidol), and hydrochlorothiazide. Oral calcium and alfacalcidol doses were also reduced to maintain serum calcium within normal range. The quality of life (QOL) score was calculated using RAND 36 QOL questionnaire at baseline and termination of the study.

STATISTICAL ANALYSIS USED

Paired t-test was used to calculate pre- and post-treatment variables.

RESULTS

Eight patients (two males) were included in this study having mean age of 35.8 years. PTH (1-34) treatment led to the improvement in serum calcium (6.81-8.84 mg/dl), phosphorous (5.8-4.2 mg/dl), and 24 h urinary calcium excretion (416-203.6 mg). Parameters of QOL showed the improvement in overall QOL, physical performance, energy, and fatigue scores. No major adverse events were noted.

CONCLUSIONS

Treatment of hypoparathyroidism with PTH (1-34) leads to improvement in calcium profile, reduction in hypercalciuria, and improvement in QOL, whereas it is safe and well tolerated.