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

Exploring Chronic Hypocalcemia: Insights into Autoimmune Polyglandular Syndrome Type 1-A Case Study and Literature Review

Hypocalcemia is a common occurrence in pediatric patients, attributed to various causes and presenting with diverse clinical manifestations. A prompt evaluation is necessary to determine its underlying cause, whether it presents acutely or chronically, and to tailor treatment based on its severity. Among the potential causes of chronic hypocalcemia, primary hypoparathyroidism stands out. The case of a seven-year-old male patient with hypocalcemia reported in this article serves as an illustration, wherein targeted next-generation sequencing revealed a homozygous p.R257X mutation in the AIRE gene, indicative of autoimmune polyendocrine syndrome type 1 (APS-1). It poses challenges due to its multisystemic nature and involvement of specific autoantibodies, often leading to underdiagnosis, owing to its rarity, varied manifestations, and incomplete penetrance. A comprehensive review of the APS-1 literature was conducted to provide insights into the clinical manifestations, genetic spectrum, potential immunological mechanisms, and current medical strategies. Additionally, the recognition of AIRE gene mutations is crucial for facilitating genetic diagnosis, prognosis, and potential treatment strategies for APS-1. The management of such cases involves individualized approaches to treatment, regular monitoring, medication adjustments, and the early identification of associated conditions.

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.

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).

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).

Metabolic Bone Diseases and New Drug Developments

Metabolic bone diseases are serious health issues worldwide, since several million individuals over the age of 50 are at risk of bone damage and should be worried about their bone health. One in every two women and one in every four men will break a bone during their lifetime due to a metabolic bone disease. Early detection, raising bone health awareness, and maintaining a balanced healthy diet may reduce the risk of skeletal fractures caused by metabolic bone diseases. This review compiles information on the most common metabolic bone diseases (osteoporosis, primary hyperparathyroidism, osteomalacia, and fluorosis disease) seen in the global population, including their symptoms, mechanisms, and causes, as well as discussing their prevention and the development of new drugs for treatment. A large amount of research literature suggests that balanced nutrition and balanced periodic supplementation of calcium, phosphate, and vitamin D can improve re-absorption and the regrowth of bones, and inhibit the formation of skeletal fractures, except in the case of hereditary bone diseases. Meanwhile, new and improved drug formulations, such as raloxifene, teriparatide, sclerostin, denosumab, and abaloparatide, have been successfully developed and administered as treatments for metabolic bone diseases, while others (romososumab and odanacatib) are in various stages of clinical trials.

Improving management of severe hypoparathyroidism: a case series

INTRODUCTION

Hypoparathyroidism is considered a rare endocrine disease. Despite being a deficiency of parathyroid hormone, the standard therapy is based on oral calcium and active vitamin D supplementation. This approach provides satisfactory management in most cases but may be inadequate for patients in the most complex spectrum of the disease. Other therapies are being explored, and among them, the use of recombinant human parathyroid hormone (PTH) has proved to decrease the requirements of calcium and active vitamin D to reach adequate therapeutic goals.

OBJECTIVE

We aimed to provide information on the effectiveness of the current recombinant parathyroid hormone analogs in the clinical management of difficult to control cases of hypoparathyroidism.

METHOD AND MATERIALS

We report our experience using teriparatide and PTH (1-84) through five complex cases of hypoparathyroidism of diverse etiologies. We describe each case and report the effectiveness of treatment in clinical practice.

RESULTS

Four patients with postsurgical hypoparathyroidism and one patient with autoimmune hypoparathyroidism, all of them with suboptimal control under the standard treatment with calcium and calcitriol supplements or calcium gluconate infusion, are presented. They were all started on teriparatide or PTH (1-84), and all of them showed a diminishment of symptoms and were able to maintain normocalcemia without parenteral calcium despite a reduction of oral treatment.

CONCLUSION

This article highlights the effectiveness and safety of hormonal replacement treatment in difficult to manage hypoparathyroidism and provides evidence which justifies its off-label prescription in the case of teriparatide. We consider that this treatment should be considered in cases in which standard treatment fails to reach adequate therapeutic goals.

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.

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.

Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy in Two Siblings: Same Mutations but Very Different Phenotypes

Autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED), caused by mutations in the AIRE gene, is mainly characterized by the triad of hypoparathyroidism, primary adrenocortical insufficiency and chronic mucocutaneous candidiasis, but can include many other manifestations, with no currently clear genotype–phenotype correlation. We present the clinical features of two siblings, a male and a female, with the same mutations in the AIRE gene associated with two very different phenotypes. Interestingly, the brother recently experienced COVID-19 infection with pneumonia, complicated by hypertension, hypokalemia and hypercalcemia. Although APECED is a monogenic disease, its expressiveness can be extremely different. In addition to the genetic basis, epigenetic and environmental factors might influence the phenotypic expression, although their exact role remains to be elucidated.

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.

Challenges in the management of chronic hypoparathyroidism

The first adjunctive hormone therapy for chronic hypoparathyroidism, recombinant human parathyroid hormone (1-84) [rhPTH(1-84)] was approved by the FDA in January 2015. Since the approval of rhPTH(1-84), growing interest has developed in other agents to treat this disorder in both the scientific community and among pharmaceutical companies. For several reasons, conventional therapy with calcium and activated vitamin D supplementation, magnesium supplementation as needed, and occasionally thiazide-type diuretic therapy remains the mainstay of treatment, while endocrinologists and patients are constantly challenged by limitations of conventional treatment. Serum calcium fluctuations, increased urinary calcium, hyperphosphatemia, and a constellation of symptoms that limit mental and physical functioning are frequently associated with conventional therapy. Understanding how conventional treatment and hormone therapy work in terms of pharmacokinetics and pharmacodynamics is key to effectively managing chronic hypoparathyroidism. Multiple questions remain regarding the effectiveness of PTH adjunctive therapy in preventing or slowing the onset and progression of the classical complications of hypoparathyroidism, such as chronic kidney disease, calcium-containing kidney stones, cataracts, or basal ganglia calcification. Several studies point toward an improvement in quality of life during replacement therapy. This review will discuss current clinical and research challenges posed by treatment of chronic hypoparathyroidism.

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.