Hypoparathyroidism: is it time for replacement therapy?

Parathyroid-on-a-chip simulating parathyroid hormone secretion in response to calcium concentration

The parathyroid gland is an endocrine organ that plays a crucial role in regulating calcium levels in blood serum through the secretion of parathyroid hormone (PTH). Hypoparathyroidism is a chronic disease that can occur due to parathyroid defects, but due to the difficulty of creating animal models of this disease or obtaining human normal parathyroid cells, the evaluation of parathyroid functionality for drug development is limited. Although parathyroid-like cells that secrete PTH have recently been reported, their functionality may be overestimated using traditional culture methods that lack in vivo similarities, particularly vascularization. To overcome these limitations, we obtained parathyroid organoids from tonsil-derived mesenchymal stem cells (TMSCs) and fabricated a parathyroid-on-a-chip, capable of simulating PTH secretion based on calcium concentration. This chip exhibited differences in PTH secretion according to calcium concentration and secreted PTH within the range of normal serum levels. In addition, branches of organoids, which are difficult to observe in animal models, were observed in this chip. This could serve as a guideline for successful engraftment in implantation therapies in the future.

A Higher Concentration of Dialysate Magnesium to Reduce the Frequency of Muscle Cramps: A Narrative Review

Purpose of review:

Strategies to mitigate muscle cramps are a top research priority for patients receiving hemodialysis. As hypomagnesemia is a possible risk factor for cramping, we reviewed the literature to better understand the physiology of cramping as well as the epidemiology of hypomagnesemia and muscle cramps. We also sought to review the evidence from interventional studies on the effect of oral and dialysate magnesium-based therapies on muscle cramps.

Sources of information:

Peer-reviewed articles.

Methods:

We searched for relevant articles in major bibliographic databases including MEDLINE and EMBASE. The methodological quality of interventional studies was assessed using a modified version of the Downs and Blacks criteria checklist.

Key findings:

The etiology of muscle cramps in patients receiving hemodialysis is poorly understood and there are no clear evidence-based prevention or treatment strategies. Several factors may play a role including a low concentration of serum magnesium. The prevalence of hypomagnesemia (concentration of <0.7 mmol/L) in patients receiving hemodialysis ranges from 10% to 20%. Causes of hypomagnesemia include a low dietary intake of magnesium, use of medications that inhibit magnesium absorption (eg, proton pump inhibitors), increased magnesium excretion (eg, high-dose loop diuretics), and a low concentration of dialysate magnesium. Dialysate magnesium concentrations of ≤0.5 mmol/L may be associated with a decrease in serum magnesium concentration over time. Preliminary evidence from observational and interventional studies suggests a higher dialysate magnesium concentration will raise serum magnesium concentrations and may reduce the frequency and severity of muscle cramps. However, the quality of evidence supporting this benefit is limited, and larger, multicenter clinical trials are needed to further determine if magnesium-based therapy can reduce muscle cramps in patients receiving hemodialysis. In studies conducted to date, increasing the concentration of dialysate magnesium appears to be well-tolerated and is associated with a low risk of symptomatic hypermagnesemia.

Limitations:

Few interventional studies have examined the effect of magnesium-based therapy on muscle cramps in patients receiving hemodialysis and most were nonrandomized, pre-post study designs.

Five-year Estimated Glomerular Filtration Rate in Patients With Hypoparathyroidism Treated With and Without rhPTH(1-84)

CONTEXT

Chronic hypoparathyroidism (HypoPT) is conventionally managed with oral calcium and active vitamin D. Recombinant human parathyroid hormone (1-84) (rhPTH[1-84]) is a therapy targeting the pathophysiology of HypoPT by replacing parathyroid hormone.

OBJECTIVE

To compare changes in the estimated glomerular filtration rate (eGFR) in patients with chronic HypoPT receiving or not receiving rhPTH(1-84) during a 5-year period.

DESIGN/SETTING

A retrospective analysis of patients with chronic HypoPT treated with or without rhPTH(1-84).

PATIENTS

Sixty-nine patients with chronic HypoPT from 4 open-label, long-term trials (NCT00732615, NCT01268098, NCT01297309, and NCT02910466) composed the rhPTH(1-84) cohort and 53 patients with chronic HypoPT not receiving rhPTH(1-84) from the Geisinger Healthcare Database (01/2004-06/2016) composed the historical control cohort.

INTERVENTIONS

The rhPTH(1-84) cohort (N = 69) received rhPTH(1-84) therapy; the historical control cohort (N = 53) did not receive rhPTH(1-84).

MAIN OUTCOME MEASURES

Changes in eGFR from baseline during a 5-year follow-up were examined in multivariate regression analyses.

RESULTS

At baseline, demographic characteristics and eGFR were similar between cohorts, though the proportions with diabetes and cardiac disorders were lower in the rhPTH(1-84) cohort. At the end of follow-up, mean eGFR increased by 2.8 mL/min/1.73 m2 in the rhPTH(1-84) cohort, while mean eGFR fell by 8.0 mL/min/1.73 m2 in the control cohort. In the adjusted model, the difference in the annual eGFR change between the rhPTH(1-84) cohort and the control cohort was 1.7 mL/min/1.73 m2 per year (P = 0.009).

CONCLUSIONS

Estimated glomerular filtration rate was preserved for over 5 years among patients with chronic HypoPT receiving rhPTH(1-84) treatment, contrasting with an eGFR decline among those not receiving rhPTH(1-84).

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.

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.

The thyroid disease in the elderly: Our experience

INTRODUCTION

The number of elderly people in Italy is growing, so it is important to study the presentation of diseases in these subjects.

MATERIALS AND METHODS

We selected 1362 patients who underwent thyroidectomy for different thyroid diseases from January 2008 to December 2014. The patients weredivided into two groups, according to the age. The patients aged 65 years and over were included in the group A, and the patients under the age of 65 years were included in the group B.

DISCUSSION

Thyroid diseases in the elderly often present with atypical symptoms which are very similar to symptoms of the aging process. In elderly hypothyroidism occurs frequently sub-clinically and hyperthyroidism is often presented with cardiovascular symptoms. In our study we evaluated the differences in incidence of thyroid diseases in the elderly and in the younger groups of patients.

CONCLUSION

The data analyzed in this study showed that in the elderly we have a reduced secretion and metabolization of thyroid hormones. The symptomatology in the elderly is nonspecific and can create a delay in the correct diagnosis.

Recombinant Human Parathyroid Hormone (1-84): A Review in Hypoparathyroidism

Full-length recombinant human parathyroid hormone [rhPTH (1-84); Natpara(®)] is approved in the USA as an adjunct to calcium and vitamin D therapy for control of hypocalcaemia in patients with hypoparathyroidism. This article reviews the clinical efficacy and tolerability of rhPTH (1-84) in hypoparathyroidism and summarizes its pharmacological properties. In a pivotal phase III trial, subcutaneous rhPTH (1-84) was effective in maintaining albumin-corrected total serum calcium levels while reducing/eliminating the need for oral calcium and active vitamin D. rhPTH (1-84) had a generally acceptable tolerability profile in this trial, with <3% of patients discontinuing treatment because of adverse events. Commonly occurring adverse reactions included hypocalcaemia, hypercalcaemia and hypercalciuria. As the first PTH replacement therapy for hypoparathyroid patients with hypocalcaemia, rhPTH (1-84) is an effective regimen, has generally acceptable tolerability and represents an important advance for the management of hypoparathyroidism.

Anticonvulsant treatment associated with intractable hypocalcaemia in a female child with hypoparathyroidism

BACKGROUND

We report the case of a female infant with hypoparathyroidism due to an activating mutation in the calcium-sensing receptor gene.

CASE REPORT

The child presented in the neonatal period with clinical seizures associated with severe hypocalcaemia, hyperphosphataemia, low parathyroid hormone levels and elevated urine calcium:creatinine ratios. She required intravenous calcium and phenobarbitone initially, and then oral 1-alfacalcidol (1-AC) and phenobarbitone were started. The patient had intractable hypocalcaemia in the first 5 months of life despite escalating doses of 1-AC. When the phenobarbitone was stopped at 5 months of age she was admitted soon after with symptomatic hypercalcaemia. We postulate that the phenobarbitone increased the metabolism of 1-AC and thus she needed large doses of 1-AC to treat hypocalcaemia until the phenobarbitone was stopped. Her parents had no biochemical abnormalities on testing.

RESULTS

Molecular genetic analysis confirmed that our patient had a de novo missense variant, c.682G>A (p.Glu228Lys) in exon 4 of the calcium-sensing receptor.

CONCLUSION

This case report highlights the importance that clinicians caring for children on vitamin D and its analogues are aware of the interaction with phenobarbitone, which can result in symptomatic hypocalcaemia. 1-AC should be stored at 2-8°C, otherwise it will be rendered inactive.

European Society of Endocrinology Clinical Guideline: Treatment of chronic hypoparathyroidism in adults

Hypoparathyroidism (HypoPT) is a rare (orphan) endocrine disease with low calcium and inappropriately low (insufficient) circulating parathyroid hormone levels, most often in adults secondary to thyroid surgery. Standard treatment is activated vitamin D analogues and calcium supplementation and not replacement of the lacking hormone, as in other hormonal deficiency states. The purpose of this guideline is to provide clinicians with guidance on the treatment and monitoring of chronic HypoPT in adults who do not have end-stage renal disease. We intend to draft a practical guideline, focusing on operationalized recommendations deemed to be useful in the daily management of patients. This guideline was developed and solely sponsored by The European Society of Endocrinology, supported by CBO (Dutch Institute for Health Care Improvement) and based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) principles as a methodological base. The clinical question on which the systematic literature search was based and for which available evidence was synthesized was: what is the best treatment for adult patients with chronic HypoPT? This systematic search found 1100 articles, which was reduced to 312 based on title and abstract. The working group assessed these for eligibility in more detail, and 32 full-text articles were assessed. For the final recommendations, other literature was also taken into account. Little evidence is available on how best to treat HypoPT. Data on quality of life and the risk of complications have just started to emerge, and clinical trials on how to optimize therapy are essentially non-existent. Most studies are of limited sample size, hampering firm conclusions. No studies are available relating target calcium levels with clinically relevant endpoints. Hence it is not possible to formulate recommendations based on strict evidence. This guideline is therefore mainly based on how patients are managed in clinical practice, as reported in small case series and based on the experiences of the authors.

22q11 deletion syndrome: current perspective

Chromosome 22q11 is characterized by the presence of chromosome-specific low-copy repeats or segmental duplications. This region of the chromosome is very unstable and susceptible to mutations. The misalignment of low-copy repeats during nonallelic homologous recombination leads to the deletion of the 22q11.2 region, which results in 22q11 deletion syndrome (22q11DS). The 22q11.2 deletion is associated with a wide variety of phenotypes. The term 22q11DS is an umbrella term that is used to encompass all 22q11.2 deletion-associated phenotypes. The haploinsufficiency of genes located at 22q11.2 affects the early morphogenesis of the pharyngeal arches, heart, skeleton, and brain. TBX1 is the most important gene for 22q11DS. This syndrome can ultimately affect many organs or systems; therefore, it has a very wide phenotypic spectrum. An increasing amount of information is available related to the pathogenesis, clinical phenotypes, and management of this syndrome in recent years. This review summarizes the current clinical and genetic status related to 22q11DS.

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.

Perioperative care in elderly patients undergoing thyroid surgery

The features of western world population are rapidly changing. The increment geriatric population obliges clinicians to implement specific recommendations and guidelines to manage these patients. In the field of thyroid surgery, when indications are represented by benign conditions, surgeons and endocrinologists tent to avoid surgery for the increased perioperative risks in the over 70 year old population. We reviewed our experience in thyroid surgery in geriatric patients within the environment of a "week surgery unit". This unit was conceived to offer a highly specialized setting for thyroid patients needing short stay after surgery. Results showed that the surgical outcomes were comparable to the ones from third surgery in young patients. The week surgery approach is the best and safest formula to offer to the geriatric population needing thyroid surgery.

Pharmacokinetics and pharmacodynamics of subcutaneous recombinant parathyroid hormone (1-84) in patients with hypoparathyroidism: an open-label, single-dose, phase I study

BACKGROUND

Impaired mineral homeostasis affecting calcium, phosphate, and magnesium is a result of parathyroid hormone (PTH) deficiency in hypoparathyroidism. The current standard of treatment with active vitamin D and oral calcium does not control levels of these major minerals. Recombinant full-length human PTH 1-84 (rhPTH[1-84]) is being developed for the treatment of hypoparathyroidism.

OBJECTIVE

The goal of this study was to investigate the pharmacokinetics and pharmacodynamics of a single subcutaneous injection of rhPTH(1-84) in patients with hypoparathyroidism.

METHODS

This was an open-label, dose-escalating study of single subcutaneous administration of 50 µg and then 100 µg of rhPTH(1-84). Enrolled patients (age range, 25-85 years) had ≥12 months of diagnosed hypoparathyroidism defined according to biochemical evidence of hypocalcemia with concomitant low-serum intact PTH and were taking doses ≥1000 mg/d of oral calcium and ≥0.25 µg/d of active vitamin D (oral calcitriol). The patient's prescribed dose of calcitriol was taken the day preceding but not on the day of or during the 24 hours after rhPTH(1-84) administration. Each patient received a single 50-µg rhPTH(1-84) dose, had at least a 7-day washout interval, and then received a single 100-µg rhPTH(1-84) dose. The following parameters were assessed: plasma PTH; serum and urine total calcium, magnesium, phosphate, and creatinine; and urine cyclic adenosine monophosphate.

RESULTS

After administration of rhPTH(1-84) 50 µg (n = 6) and 100 µg (n = 7), the approximate t½ was 2.5 to 3 hours. Plasma PTH levels increased rapidly, then declined gradually back to predose levels at ~12 hours. The median AUC was similar with calcitriol and rhPTH(1-84) for serum 1,25-dihydroxyvitamin D (calcitriol, 123-227 pg · h/mL; rhPTH[1-84], 101-276 pg · h/mL), calcium (calcitriol, 3.3-3.7 mg · h/dL; rhPTH[1-84], 3.3-7.6 mg · h/dL), and magnesium (calcitriol, 0.7-0.9 mg · h/dL; rhPTH[1-84], 1.3-2.8 mg · h/dL). In contrast, the median AUC for phosphate was strongly negative with rhPTH(1-84) (calcitriol, -1.0 to 0.8 mg · h/dL; rhPTH[1-84], -21.3 to -26.5 mg · h/dL). Compared with calcitriol, rhPTH(1-84) 50 µg reduced 24-hour calcium excretion and calcium-to-creatinine ratios by 12% and 23%, respectively, and rhPTH(1-84) 100 µg reduced them by 26% and 27%. There was little overall impact on urine magnesium levels. Compared with calcitriol, rhPTH(1-84) 50 µg increased urinary phosphate excretion and phosphate-to-creatinine ratios by 53% and 54%, respectively, and rhPTH(1-84) 100 µg increased them by 45% and 42%. Urine cyclic adenosine monophosphate-to-creatinine ratio increased with rhPTH(1-84) by 2.3-fold (50 µg) and 4.4-fold (100 µg) compared with calcitriol.

CONCLUSIONS

PTH replacement therapy with rhPTH(1-84) regulated mineral homeostasis of calcium, magnesium, phosphate, and vitamin D metabolism toward normal in these study patients with hypoparathyroidism.

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

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

The effect of continuous subcutaneous recombinant PTH (1-34) infusion during pregnancy on calcium homeostasis - a case report

OBJECTIVE

We describe calcium homeostasis during pregestation and gestation in a woman with iatrogenic hypoparathyroidism, treated with continuous subcutaneous recombinant parathyroid hormone (PTH) (1-34) infusion.

RESULTS

The requirement for PTH did not fluctuate much during pregnancy and was essential for maintaining normal calcium and phosphorus serum levels.

CONCLUSIONS

This study documents the insufficiency of PTH-related protein (PTHrP) or other gestation-related hormones to compensate for PTH deficiency in hypoparathyroid women, and the successful utilization of continuous subcutaneous recombinant PTH (1-34) infusion to achieve normal calcium homeostasis during gestation. Clinical trials with PTH replacement in such circumstances are warranted.

Questionable safety of thyroid surgery with same day discharge

INTRODUCTION

Over the last two decades increasing numbers of surgical procedures have been performed on an outpatient basis. In 2000 the National Health Service in England set the target of performing 75% or more of all elective surgical procedures as day cases and in 2001 the British Association of Day Surgery added thyroidectomy to the list of day case procedures. However, same day discharge following thyroidectomies has been adopted by only a very small number of UK centres. The aim of this review was to establish the evidence base surrounding same day discharge thyroid surgery.

METHODS

The British Association of Endocrine and Thyroid Surgeons commissioned the authors to perform a review of the best available evidence regarding day case thyroid surgery as a part of a consensus position to be adopted by the organisation. A MEDLINE(®)review of the English medical literature was performed and the relevant articles were collated and reviewed.

RESULTS

There are limited comparative data on day case thyroid surgery. It is feasible and may save individual hospitals the cost of inpatient stay. However, the risk of airway compromising and life threatening post-operative bleeding remains a major concern since it is not possible to positively identify those patients most and least at risk of bleeding after thyroidectomy. It is estimated that half of all post-thyroidectomy bleeds would occur outside of the hospital environment if patients were discharged six hours after surgery.

CONCLUSIONS

Same day discharge in a UK setting cannot be endorsed. Any financial benefits may be outweighed by the exposure of patients to an increased risk of an adverse outcome. Consequently, 23-hour surgery is recommended.

Hypocalcemia: updates in diagnosis and management for primary care

OBJECTIVE

To provide family physicians with an evidence-based approach to the diagnosis and management of hypocalcemia. Quality of evidence MEDLINE and EMBASE articles from 2000 to 2010 were searched, with a focus on the diagnosis and management of hypocalcemia. Levels of evidence (I to III) were cited where appropriate, with most studies providing level II or III evidence. References of pertinent papers were also searched for relevant articles. Main message Chronic hypocalcemia is commonly due to inadequate levels of parathyroid hormone or vitamin D, or due to resistance to these hormones. Treatment focuses on oral calcium and vitamin D supplements, as well as magnesium if deficiency is present. Treatment can be further intensified with thiazide diuretics, phosphate binders, and a low-salt and low-phosphorus diet when treating hypocalcemia secondary to hypoparathyroidism. Acute and life-threatening calcium deficit requires treatment with intravenous calcium.The current treatment recommendations are largely based on expert clinical opinion and published case reports,as adequately controlled clinical trial data are not currently available. Complications of current therapies for hypoparathyroidism include hypercalciuria, nephrocalcinosis, renal impairment, and soft tissue calcification. Current therapy is limited by serum calcium fluctuations. Although these complications are well recognized, the effects of therapy on overall well-being, mood, cognition, and quality of life, as well as the risk of complications,have not been adequately studied.

CONCLUSION

Family physicians play a crucial role in educating patients about the long-term management and complications of hypocalcemia. Currently, management is suboptimal and marked by fluctuations in serum calcium and a lack of approved parathyroid hormone replacement therapy for hypoparathyroidism.

Synthetic human parathyroid hormone 1-34 replacement therapy: a randomized crossover trial comparing pump versus injections in the treatment of chronic hypoparathyroidism

CONTEXT

Vitamin D therapy for hypoparathyroidism does not restore PTH-dependent renal calcium reabsorption, which can lead to renal damage. An alternative approach, PTH 1-34 administered twice daily, provides acceptable long-term treatment but is associated with nonphysiological serum calcium fluctuation.

OBJECTIVE

Our objective was to compare continuous PTH 1-34 delivery, by insulin pump, with twice-daily delivery.

RESEARCH DESIGN AND METHODS

In a 6-month, open-label, randomized, crossover trial, PTH 1-34 was delivered by pump or twice-daily sc injection. After each 3-month study period, serum and 24-h urine mineral levels and bone turnover markers were measured daily for 3 d, and 24-h biochemical profiles were determined for serum minerals and 1,25-dihydroxyvitamin D(3) and for urine minerals and cAMP. STUDY PARTICIPANTS AND SETTING: Eight patients with postsurgical hypoparathyroidism (mean ± sd age 46 ± 5.6 yr) participated at a tertiary care referral center.

RESULTS

Pump vs. twice-daily delivery of PTH 1-34 produced less fluctuation in serum calcium, a more than 50% reduction in urine calcium (P = 0.002), and a 65% reduction in the PTH dose to maintain eucalcemia (P < 0.001). Pump delivery also produced higher serum magnesium level (P = 0.02), normal urine magnesium, and reduced need for magnesium supplements. Finally, pump delivery normalized bone turnover markers and significantly lowered urinary cross-linked N-telopeptide of type 1 collagen and pyridinium crosslinks compared with twice-daily injections (P < 0.05).

CONCLUSION

Pump delivery of PTH 1-34 provides the closest approach to date to physiological replacement therapy for hypoparathyroidism.

Hypoparathyroidism in the adult: epidemiology, diagnosis, pathophysiology, target-organ involvement, treatment, and challenges for future research

Recent advances in understanding the epidemiology, genetics, diagnosis, clinical presentations, skeletal involvement, and therapeutic approaches to hypoparathyroidism led to the First International Workshop on Hypoparathyroidism that was held in 2009. At this conference, a group of experts convened to discuss these issues with a view towards a future research agenda for this disease. This review, which focuses primarily on hypoparathyroidism in the adult, provides a comprehensive summary of the latest information on this disease.

The effect of adding PTH(1-84) to conventional treatment of hypoparathyroidism: a randomized, placebo-controlled study

In hypoparathyroidism, plasma parathyroid hormone (PTH) levels are inadequate to maintain plasma calcium concentration within the reference range. On conventional treatment with calcium supplements and active vitamin D analogues, bone turnover is abnormally low, and BMD is markedly increased. We aimed to study the effects of PTH-replacement therapy (PTH-RT) on calcium-phosphate homeostasis and BMD. In a double-blind design, we randomized 62 patients with hypoparathyroidism to daily treatment with PTH(1-84) 100 µg or similar placebo for 24 weeks as add-on therapy to conventional treatment. Compared with placebo, patients on PTH(1-84) reduced their daily dose of calcium and active vitamin D significantly by 75% and 73%, respectively, without developing hypocalcemia. However, hypercalcemia occurred frequently during the downtitration of calcium and active vitamin D. Plasma phosphate and renal calcium and phosphate excretion did not change. Compared with placebo, PTH(1-84) treatment significantly increased plasma levels of bone-specific alkaline phosphatase (+226% ± 36%), osteocalcin (+807% ± 186%), N-terminal propeptide of procollagen 1 (P1NP; +1315% ± 330%), cross-linked C-telopeptide of type 1 collagen (CTX; +1209% ± 459%), and urinary cross-linked N-telopeptide of type 1 collagen (NTX; (+830% ± 165%), whereas BMD decreased at the hip (-1.59% ± 0.57%), lumbar spine (-1.76% ± 1.03%), and whole body (-1.26% ± 0.49%) but not at the forearm. In conclusion, the need for calcium and active vitamin D is reduced significantly during PTH-RT, whereas plasma calcium and phosphate levels are maintained within the physiologic range. In contrast to the effect of PTH(1-84) treatment in patients with osteoporosis, PTH-RT in hypoparathyroidism causes a decrease in BMD. This is most likely due to the marked increased bone turnover. Accordingly, PTH-RT counteracts the state of overmineralized bone and, during long-term treatment, may cause a more physiologic bone metabolism.

Mutations of calcium-sensing receptor gene: two novel mutations and overview of impact on calcium homeostasis

OBJECTIVE

Genetic disorders of calcium metabolism arise in a familial or sporadic setting. The calcium-sensing receptor (CASR) plays a key role in maintaining calcium homeostasis and study of the CASR gene can be clinically useful in determining etiology and appropriate therapeutic approaches. We report two cases of novel CASR gene mutations that illustrate the varying clinical presentations and discuss these in terms of the current understanding of CASR function.

PATIENTS AND METHODS

A 16-year-old patient had mild hypercalcemia associated with low-normal urinary calcium excretion and normal-to-high parathyroid hormone (PTH) levels. Because of negative family history, familial hypocalciuric hypercalcemia was originally excluded. The second patient was a 54-year-old man with symptomatic hypocalcemia, hyperphosphatemia, low PTH, and mild hypercalciuria. Familial investigation revealed the same phenotype in the patient's sister. The coding region of the CASR gene was sequenced in both probands and their available first-degree relatives.

RESULTS

The first patient had a novel heterozygous inactivating CASR mutation in exon 4, which predicted a p.A423K change; genetic analysis was negative in the parents. The second patient had a novel heterozygous activating CASR mutation in exon 6, which predicted a p.E556K change; the affected sister of the proband was also positive.

CONCLUSIONS

We reported two novel heterozygous mutations of the CASR gene, an inactivating mutation in exon 4 and the first activating mutation reported to date in exon 6. These cases illustrate the importance of genetic testing of CASR gene to aid correct diagnosis and to assist in clinical management.