PTH replacement therapy of hypoparathyroidism

Hypoparathyroidism: Musculoskeletal Manifestations Related to Parathormone Deficiency

BACKGROUND

Hypoparathyroidism is a rare metabolic disorder that can be responsible for musculoskeletal manifestations.

AIM

We present a systematic review of musculoskeletal manifestations of adult-onset nonsurgical nongenetic hypoparathyroidism.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline using the MEDLINE database, including manuscripts describing musculoskeletal manifestations of adult-onset nonsurgical nongenetic hypoparathyroidism.

RESULTS

Musculoskeletal manifestations included myopathy, shoulder disorder, immune-negative non-erosive peripheral arthritis, axial involvement simulating spondylarthritis, and diffuse ligamentous ossifications. An association between hypoparathyroidism and spondyloarthritis or autoimmune diseases is possible. T-cell activation, seen in patients with hypoparathyroidism, may explain the co-occurrence of hypoparathyroidism with other autoimmune diseases. The treatment of these manifestations is based on calcium and active vitamin D supplementation. Parathyroid hormone may have an anabolic effect on muscle atrophy and muscle weakness. Parathyroid hormone can also promote bone formation and bone resorption by stimulating osteoclast differentiation by increasing RANKL (receptor activator for nuclear factor kappa-B ligand) expression. Therefore, hypoparathyroidism can be responsible for an increase in bone mineral density. However, the risk of fractures does not appear to be reduced due to changes in bone microarchitecture and the high risk of falls. Treatment with parathyroid hormone has been shown to improve bone microarchitecture.

CONCLUSION

Our review showed that musculoskeletal manifestations are frequent in patients with hypoparathyroidism, including muscular, axial, peripheral articular, and entheseal manifestations.

[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.

Development of Surgically Transplantable Parathyroid Hormone-Releasing Microbeads

Hypoparathyroidism is an endocrine disorder that occurs because of the inability to produce parathyroid hormone (PTH) effectively. Previously, we reported the efficacy of tonsil-derived mesenchymal stem cells (TMSCs) differentiated into parathyroid-like cells for the treatment of hypoparathyroidism. Here, we investigated the feasibility of three-dimensional structural microbeads fabricated with TMSCs and alginate, a natural biodegradable polymer, to treat hypoparathyroidism. Alginate microbeads were fabricated by dropping a 2% (w/v) alginate solution containing TMSCs into a 5% CaCl2 solution and then differentiated into parathyroid-like cells using activin A and sonic hedgehog for 7 days. The protein expression of PTH, a specific marker of the parathyroid gland, was significantly higher in differentiated alginate microbeads with TMSCs (Al-dT) compared with in undifferentiated alginate microbeads with TMSCs. For in vivo experiments, we created the hypoparathyroidism animal model by parathyroidectomy (PTX) and implanted alginate microbeads in the dorsal interscapular region. The PTX rats with Al-dT (PTX+Al-dT) showed the highest survival rate and weight change and a gradual increase in serum intact PTH levels. We also detected a higher expression of PTH in retrieved tissues of PTX+Al-dT using immunofluorescence analysis. This study demonstrates that alginate microbeads are potential a new tool as a surgically scalable therapy for treating hypoparathyroidism.

Skeletal abnormalities in Hypoparathyroidism and in Primary Hyperparathyroidism

Both hypoparathyroidism (HypoPT), as well as its pathological counterpart, primary hyperparathyroidism (PHPT), can lead to skeletal abnormalities. Chronic deficiency of PTH in patients with HypoPT is associated with a profound reduction in bone remodeling, with consequent increases in bone density, and abnormalities in microarchitecture and bone strength. It is still not clear whether there is an increase in fracture risk in HypoPT. While standard therapy with calcium supplements and active vitamin D does not restore bone homeostasis, treatment of HypoPT with PTH appears to correct some of those abnormalities. In PHPT, the continuous exposure to high levels of PTH causes an increase in bone remodeling, in which bone resorption prevails. In the symptomatic form of PHPT, patients can present with fragility fractures, and/or the classical radiological features of osteitis fibrosa cystica. However, even in mild PHPT, catabolic skeletal actions of PTH are evident through reduced BMD, deterioration of bone microarchitecture and increased risk of fragility fractures. Successful parathyroidectomy improves skeletal abnormalities. Medical treatment, such as bisphosphonates and denosumab, can also increase bone density in patients with PHPT who do not undergo surgery. This article reviews skeletal involvement in HypoPT and in PHPT, as assessed by bone remodeling, DXA, trabecular bone score, and quantitative computed tomography, as well as data on bone strength and fracture risk. The effects of PTH replacement on the skeleton in subjects with HypoPT, and the outcome of parathyroidectomy in patients with PHPT, are also reviewed here.

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.

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.

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.

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.

Lead Optimization and Avoidance of Reactive Metabolite Leading to PCO371, a Potent, Selective, and Orally Available Human Parathyroid Hormone Receptor 1 (hPTHR1) Agonist

We have previously shown that the oral administration of the small molecule hPTHR1 agonist PCO371 and its lead compound, 1 (CH5447240) results in PTH-like calcemic and hypophostemic activity in thyroparathyroidectomized rats. However, 1 was converted to a reactive metabolite in a human liver microsome assay. In this article, we report on the modification path that led to an enhancement of PTHR1 agonistic activity and reduction in the formation of a reactive metabolite to result in a potent, selective, and orally active PTHR1 agonist 1-(3,5-dimethyl-4-(2-((4-oxo-2-(4-(trifluoromethoxy)phenyl)-1,3,8-triazaspiro[4.5]dec-1-en-8-yl)sulfonyl)ethyl)phenyl)-5,5-dimethylimidazolidine-2,4-dione (PCO371, 16c). This compound is currently being evaluated in a phase 1 clinical study for the treatment of hypoparathyroidism.

Biomechanical and tomographic differences in the microarchitecture and strength of trabecular and cortical bone in the early stage of male osteoporosis

Osteoporosis is a continuous process of loss of bone tissue. Compared to women, osteoporosis in men is associated with greater morbidity and mortality. In this study, we conducted tomographic and biomechanical evaluations of trabecular and cortical bone in the early stage of male osteoporosis. Male Wistar rats were subjected to orchiectomy and sham operation. Four weeks after being castrated, decreased levels of testosterone in plasma were found and resulted in concurrent bone loss. Separately, the orchiectomy led to significant tomographic alterations in the trabecular bone number, trabecular separation, and trabecular pattern factor. Data of a mechanistic compression test further showed that the orchiectomy diminished the maximum loading force, displacement at maximum load, energy at maximum load, and ultimate stress. Interestingly, orchiectomy-triggered changes in the maximum loading force and tomographic parameters were highly correlated. In contrast, tomographic and biomechanical analyses showed that 4 weeks after rats were orchiectomized, the thickness, area, maximum loading force, bone stiffness, energy at maximum load, and ultimate stress of the cortical bone were not changed. Taken together, this study showed specific differences in the microarchitecture and strength of trabecular bone in the early stage of male osteoporosis.

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.

Development of a Novel Human Parathyroid Hormone Receptor 1 (hPTHR1) Agonist (CH5447240), a Potent and Orally Available Small Molecule for Treatment of Hypoparathyroidism

During the course of derivatization of HTS hit 4a, we have identified a novel small-molecule hPTHR1 agonist, 1-(3,5-dimethyl-4-(2-((2-((1 R,4 R)-4-methylcyclohexyl)-4-oxo-1,3,8-triazaspiro[4.5]dec-1-en-8-yl)sulfonyl)ethyl)phenyl)-1-methylurea (CH5447240, 14l). Compound 14l exhibited a potent in vitro hPTHR1 agonist effect with EC₂₀ of 3.0 μM and EC₅₀ of 12 μM and showed excellent physicochemical properties, such as high solubility in fasted state simulated intestinal fluid and good metabolic stability in human liver microsomes. Importantly, 14l showed 55% oral bioavailability and a significantly elevated serum calcium level in hypocalcemic model rats.

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.

Bone imaging in hypoparathyroidism

Hypoparathyroidism (HypoPT) is an uncommon endocrine disorder characterized by chronic deficiency or absence of parathyroid hormone (PTH), which leads to a profound reduction in bone remodeling. Subjects with HypoPT typically have bone mineral densities (BMDs) by dual-energy X-ray absorptiometry (DXA) above average at all skeletal sites, with greatest scores observed at the lumbar spine. Trabecular bone score (TBS), an indirect measure of bone microarchitecture, also appears to be normal in HypoPT. By peripheral quantitative computed tomography (pQCT) of the radius, volumetric BMD at cancellous and cortical compartments, as well as cortical area and thickness, are greater in hypoparathyroid subjects than in controls. The use of high-resolution pQCT (HRpQCT) confirmed the increase in cortical volumetric BMD but demonstrated reduced cortical thickness, associated with lower cortical porosity in HypoPT. Trabeculae tend to be more numerous but thinner in hypoparathyroid subjects. It is not clear whether these structural and the dynamic skeletal abnormalities in HypoPT affect bone strength or fracture risk. Treatment of HypoPT with PTH leads to improvement in bone remodeling rate, variable changes in bone density, and a transient increase in estimated bone strength. The effect of PTH therapy on fracture risk remains unknown. This article reviews skeletal involvement and the effect of PTH treatment in patients with HypoPT, as assessed by DXA, TBS, QCT, and HRpQCT. Data on bone strength and fracture risk in HypoPT are also reviewed here.

Identification of an orally active small-molecule PTHR1 agonist for the treatment of hypoparathyroidism

Parathyroid hormone (PTH) is essential for calcium homeostasis and its action is mediated by the PTH type 1 receptor (PTHR1), a class B G-protein-coupled receptor. Hypoparathyroidism and osteoporosis can be treated with PTH injections; however, no orally effective PTH analogue is available. Here we show that PCO371 is a novel, orally active small molecule that acts as a full agonist of PTHR1. PCO371 does not affect the PTH type 2 receptor (PTHR2), and analysis using PTHR1–PTHR2 chimeric receptors indicated that Proline 415 of PTHR1 is critical for PCO371-mediated PTHR1 activation. Oral administration of PCO371 to osteopenic rats provokes a significant increase in bone turnover with limited increase in bone mass. In hypocalcemic rats, PCO371 restores serum calcium levels without increasing urinary calcium, and with stronger and longer-lasting effects than PTH injections. These results strongly suggest that PCO371 can provide a new treatment option for PTH-related disorders, including hypoparathyroidism.

Hypoparathyroidism and osteoporosis can be treated with parathyroid hormone, but frequent injections are required. Here the authors develop a small-molecule agonist for the parathyroid hormone type I receptor that can be administered orally, and demonstrate its efficacy in rats.

Standardization of A Physiologic Hypoparathyroidism Animal Model

Ideal hypoparathyroidism animal models are a prerequisite to developing new treatment modalities for this disorder. The purpose of this study was to evaluate the feasibility of a model whereby rats were parathyroidectomized (PTX) using a fluorescent-identification method and the ideal calcium content of the diet was determined. Thirty male rats were divided into surgical sham (SHAM, n = 5) and PTX plus 0, 0.5, and 2% calcium diet groups (PTX-FC (n = 5), PTX-NC (n = 10), and PTX-HC (n = 10), respectively). Serum parathyroid hormone levels decreased to non-detectable levels in all PTX groups. All animals in the PTX—FC group died within 4 days after the operation. All animals survived when supplied calcium in the diet. However, serum calcium levels were higher in the PTX-HC than the SHAM group. The PTX-NC group demonstrated the most representative modeling of primary hypothyroidism. Serum calcium levels decreased and phosphorus levels increased, and bone volume was increased. All animals survived without further treatment and did not show nephrotoxicity including calcium deposits. These findings demonstrate that PTX animal models produced by using the fluorescent-identification method, and fed a 0.5% calcium diet, are appropriate for hypoparathyroidism treatment studies.

PTH and Vitamin D

PTH and Vitamin D are two major regulators of mineral metabolism. They play critical roles in the maintenance of calcium and phosphate homeostasis as well as the development and maintenance of bone health. PTH and Vitamin D form a tightly controlled feedback cycle, PTH being a major stimulator of vitamin D synthesis in the kidney while vitamin D exerts negative feedback on PTH secretion. The major function of PTH and major physiologic regulator is circulating ionized calcium. The effects of PTH on gut, kidney, and bone serve to maintain serum calcium within a tight range. PTH has a reciprocal effect on phosphate metabolism. In contrast, vitamin D has a stimulatory effect on both calcium and phosphate homeostasis, playing a key role in providing adequate mineral for normal bone formation. Both hormones act in concert with the more recently discovered FGF23 and klotho, hormones involved predominantly in phosphate metabolism, which also participate in this closely knit feedback circuit. Of great interest are recent studies demonstrating effects of both PTH and vitamin D on the cardiovascular system. Hyperparathyroidism and vitamin D deficiency have been implicated in a variety of cardiovascular disorders including hypertension, atherosclerosis, vascular calcification, and kidney failure. Both hormones have direct effects on the endothelium, heart, and other vascular structures. How these effects of PTH and vitamin D interface with the regulation of bone formation are the subject of intense investigation.

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

CONTEXT

Conventional therapy for hypoparathyroidism consists of calcium and calcitriol, but sometimes normal serum calcium cannot be maintained, and/or this approach might lead to nephrocalcinosis, nephrolithiasis, or renal insufficiency.

OBJECTIVE

The objective of the study was to investigate the effects of 6 months of PTH(1-34) treatment in adult subjects with postoperative hypoparathyroidism and to evaluate quality-of-life changes.

DESIGN

This was a 2-year prospective, open-label study. At baseline and after 6 months of PTH(1-34) treatment, calcium and vitamin D supplementation requirements, serum calcium, phosphate, creatinine, alkaline phosphatase, uric acid, and 24-hour urinary calcium excretion were evaluated. Quality of life was evaluated by the Rand 36-Item Short Form Health Survey covering eight domains of physical and mental health.

SETTING

This was an Italian multicentric study.

PARTICIPANTS

Participants included 42 subjects with surgical hypoparathyroidism (90% females, age range 34-77 y).

INTERVENTION

The intervention included a twice-daily PTH(1-34) 20 μg sc injection.

RESULTS

The mean serum calcium levels significantly increased from baseline to 15 days (7.6 ± 0.6 vs 9.1 ± 0.9 mg/dL, P < .001) and remained stable until the end of the observational period, despite a significant reduction in calcium and vitamin D supplementation. Phosphate levels gradually decreased from baseline to the sixth month (P = .005 for the trend), whereas the alkaline phosphatase increased (P < .001). Data from the Rand 36-Item Short Form Health Survey showed a significant improvement in the mean scores of all eight domains (P < .001).

CONCLUSION

This is the largest study that demonstrates the effectiveness of PTH(1-34) in the treatment of adult patients with postsurgical hypoparathyroidism, and it shows that PTH(1-34) may improve the mental and physical health in hypoparathyroid subjects.

Effects of pump versus twice-daily injection delivery of synthetic parathyroid hormone 1-34 in children with severe congenital hypoparathyroidism

OBJECTIVE

To compare the response with synthetic human parathyroid hormone (PTH) 1-34 delivered by twice-daily injection vs insulin pump in children with severe congenital hypoparathyroidism due to calcium receptor mutation or autoimmune polyglandular syndrome type 1.

STUDY DESIGN

Children and young adults aged 7-20 years with congenital hypoparathyroidism (N = 12) were randomized to receive PTH 1-34, delivered either by twice-daily subcutaneous injection or insulin pump for 13 weeks, followed by crossover to the opposite delivery method. The principal outcome measures were serum and urine calcium levels. Secondary outcomes included serum and urine magnesium and phosphate levels and bone turnover markers.

RESULTS

PTH 1-34 delivered via pump produced near normalization of mean serum calcium (2.02 ± 0.05 [pump] vs 1.88 ± 0.03 [injection] mmol/L, P < .05, normal 2.05-2.5 mmol/L), normalized mean urine calcium excretion (5.17 ± 1.10 [pump] vs 6.67 ± 0.76 mmol/24 h/1.73 m(2), P = .3), and significantly reduced markers of bone turnover (P < .02). Serum and urine calcium and magnesium showed a biphasic pattern during twice-daily injection vs minimal fluctuation during pump delivery. The PTH 1-34 dosage was markedly reduced during pump delivery (0.32 ± 0.04 vs 0.85 ± 0.11 μg/kg/d, P < .001), and magnesium supplements were also reduced (P < .001).

CONCLUSION

Compared with twice-daily delivery, pump delivery of PTH 1-34 provides more physiologic calcium homeostasis and bone turnover in children with severe congenital hypoparathyroidism.

Efficacy and safety of recombinant human parathyroid hormone (1-84) in hypoparathyroidism (REPLACE): a double-blind, placebo-controlled, randomised, phase 3 study

BACKGROUND

Hypoparathyroidism results in impaired mineral homoeostasis, including hypocalcaemia and hyperphosphataemia. Treatment with high-dose oral calcium and active vitamin D does not provide adequate or consistent control of biochemical indices and can lead to serious long-term complications. We aimed to test the efficacy, safety, and tolerability of once-daily recombinant human parathyroid hormone 1-84 (rhPTH[1-84]) in adults with hypoparathyroidism.

METHODS

In this double-blind, placebo-controlled, randomised phase 3 study (REPLACE), we recruited patients with hypoparathyroidism (≥ 18 months duration) aged 18-85 years from 33 sites in eight countries. After an optimisation period, during which calcium and active vitamin D doses were adjusted to achieve consistent albumin-corrected serum calcium, patients were randomly assigned (2:1) via an interactive voice response system to 50 μg per day of rhPTH(1-84) or placebo for 24 weeks. Active vitamin D and calcium were progressively reduced, while rhPTH(1-84) could be titrated up from 50 μg to 75 μg and then 100 μg (weeks 0-5). The primary endpoint was the proportion of patients at week 24 who achieved a 50% or greater reduction from baseline in their daily dose of oral calcium and active vitamin D while maintaining a serum calcium concentration greater than or the same as baseline concentrations and less than or equal to the upper limit of normal, analysed by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00732615.

FINDINGS

Between June 23, 2009, and Feb 28, 2011, 134 eligible patients were recruited and randomly assigned to rhPTH(1-84) (n=90) or placebo (n=44). Six patients in the rhPTH(1-84) group and seven in the placebo group discontinued before study end. 48 (53%) patients in the rhPTH(1-84) group achieved the primary endpoint compared with one (2%) patient in the placebo group (percentage difference 51.1%, 95% CI 39.9-62.3; p<0.0001). The proportions of patients who had at least one adverse event were similar between groups (84 [93%] patients in the rhPTH[1-84] group vs 44 [100%] patients in the placebo group), with hypocalcaemia, muscle spasm, paraesthesias, headache, and nausea being the most common adverse events. The proportions of patients with serious adverse events were also similar between the rhPTH(1-84) group (ten [11%] patients) and the placebo group (four [9%] patients).

INTERPRETATION

50 μg, 75 μg, or 100 μg per day of rhPTH(1-84), administered subcutaneously in the outpatient setting, is efficacious and well tolerated as a PTH replacement therapy for patients with hypoparathyroidism.