Nephrocalcinosis, Renal Dysfunction, and Calculi in Patients With Primary Hypoparathyroidism on Long-Term Conventional Therapy

Significance of QTc Interval in Chronic Hypoparathyroidism and its Correlates

CONTEXT

Hypocalcemia predisposes patients with chronic hypoparathyroidism (cHypoPT) to an increased risk of QTc prolongation and life-threatening arrhythmias. Information on clinical and biochemical correlates of QTc in cHypoPT is limited.

OBJECTIVE

To assess the significance of QTc interval in chronic hypoparathyroidism and its correlates.

METHODS

This was an observational cohort study at a tertiary care center. Eighty-eight nonsurgical patients with cHypoPT (mean age 44.1 ± 15.4 years, 45 males) were assessed for QTc interval and its possible correlates including arrhythmic symptoms (palpitation/giddiness/syncope), serum total calcium, phosphate, 25(OH)D, and intact parathyroid hormone.

RESULTS

The mean QTc in the HypoPT cohort was 428 ± 34 ms with 13.6% having prolonged QTc. There was a significant inverse correlation between QTc interval and serum total calcium measured on the same day (r = -0.43, P < .001). The mean serum total calcium was significantly lower in patients with prolonged QTc (7.05 ± 1.94 vs 8.49 ± 1.01 mg/dL, P = .02). Of patients with cHypoPT 21.6% had arrhythmic symptoms. They had significantly higher mean QTc (P = .02) and also tended to have lower mean serum total calcium during follow-up (P = .06). In multivariable regression, female gender, higher current age, higher body mass index, and low serum total calcium showed significant association with prolonged QTc. For every mg/dL decrease in serum total calcium, QTc increased by 13 ms. Receiver operating characteristic analysis revealed serum total calcium at cut-off of 8.3 mg/dL discriminated prolonged QTc with area under the curve being 0.72 (95% CI 0.51, 0.93).

CONCLUSION

One-fifth of patients with cHypoPT had arrhythmic symptoms and a significant proportion had prolonged QTc. This highlights the need for close monitoring of patients with cHypoPT for arrhythmic symptoms and QTc prolongation. The serum total calcium should be maintained to at least 8.3 mg/dL to minimize the risk of potentially life-threatening arrhythmia in cHypoPT.

Renal complications in chronic hypoparathyroidism - a systematic cross-sectional assessment

Context

Although renal long-term complications are acknowledged in chronic hypoparathyroidism (HPT), standardized investigations are scarce.

Objective

To systematically investigate renal complications and their predictors in hypoparathyroid patients compared to matched individuals.

Design

Prospective observational study in 161 patients with chronic HPT.

Methods

Patients received renal ultrasound, clinical and laboratory assessments. An individual 1:3 matching with participants from the German population-based Study of Health in Pomerania was performed.

Results

Of 161 patients (92% postoperative HPT), prevalence of eGFR <60ml/min/1.73m2 was 21%, hypercalciuria 41%. Compared to healthy individuals, HPT patients had a significantly lower eGFR (74.2 vs. 95.7 ml/min/1.73m², p<0.01). Renal ultrasound revealed calcifications in 10% (nephrocalcinosis in 7% and calculi in 3%). Patients with renal calcifications had higher levels of 24-hour urine calcium excretion (8.34 vs. 5.08 mmol/d, p=0.02), spot urine calcium excretion (4.57 vs. 2.01 mmol/L, p=0.01) and urine calcium-to-creatinine ratio (0.25 vs. 0.16, p<0.01) than patients without calcifications. Albumin-corrected calcium, phosphate, calcium-phosphate product, 25-hydroxyvitamin D in serum, eGFR, daily calcium intake or disease duration were not significantly different between these two groups. Including patients receiving rhPTH therapy, a lower serum phosphate concentration (odds ratio 1.364 [95% confidence interval (CI) 1.049-1.776], p<0.05) and a longer disease duration of HPT (odds ratio 1.063 [95% CI 1.021-1.106], p<0.01) were significant predictors for renal calcifications. Excluding patients receiving rhPTH therapy, a higher 24-hour urine calcium excretion (odds ratio 1.215 [95% CI 1.058-1.396], p<0.01) was a significant predictor for renal calcifications but not serum magnesium or disease duration.

Conclusions

Prevalence of impaired renal function among patients with chronic HPT is increased and independent from visible renal calcifications. Depending on exclusion of patients with rhPTH therapy, regression analysis revealed disease duration and serum phosphate or disease duration and 24-hour urinary calcium excretion as predictors for renal calcifications.

Clin Trials Identifier

NCT05585593.

Coronary artery disease and its vascular associates in patients with chronic nonsurgical hypoparathyroidism

OBJECTIVE

Patients with chronic hypoparathyroidism (cHypoPT) are prone to intracranial-calcification, cataract and nephrocalcinosis. In this study, we systematically investigated the possibility of increased coronary artery calcification (CAC) and coronary artery disease (CAD) in them.

DESIGN

Cross-sectional.

PATIENTS AND MEASUREMENTS

Ninety-four nonsurgical cHypoPT (M:F = 50:44; age = 45 ± 15 years) with 18.6 ± 9.3 years of illness were assessed. Those with dyspnoea, angina, syncope, abnormal electrocardiogram, echocardiography or significant CAC underwent coronary angiography or myocardial-perfusion-stress imaging. Their lipid parameters and high-sensitivity C-reactive protein (hsCRP) were compared with age-matched healthy controls (Group A, n = 101). The prevalence of CAC in cHypoPT was compared with that of subjects referred from cardiology-clinics (Group B, n = 148, age = 52 ± 11 years).

RESULTS

One of 94 cHypoPT had known CAD. On screening, 17 cHypoPT required evaluation for CAD. Two of 17 had severe coronary stenosis, and 12 showed subclinical CAD. CAC and aortic-valve calcification occurred in 21.5% and 11.8%. Clinical and subclinical CAD, CAC and aortic-valve calcification in cHypoPT ≥50 years of age was 8.1%, 27.0%, 52.8% and 27.8%, respectively. Frequency of age-adjusted CAC was comparable between cHypoPT and control Group B (30.2% vs. 30.7%, p = .93). Elevated hsCRP was higher in cHypoPT than in controls A (52% vs. 32%, p < .01). Factors associated with CAD in cHypoPT were CAC and hypertension. However, CAD and CAC showed no association with long-term calcemic or phosphatemic control and intracranial-calcification in cHypoPT.

CONCLUSIONS

Clinical and subclinical CAD was observed in 3.2% and 12.8% of cHypoPT patients. The increased prevalence of CAD, CAC and aortic-valve calcification in cHypoPT above 50 years of age suggested their careful cardiac evaluation during follow-up.

A novel case of homozygous PAX1 mutation associated with hypoparathyroidism

The PAX1 gene plays an important role in the development of the parathyroid glands and the thymus. Mouse knockout models of PAX1, PAX3, and PAX9 have been found to have hypoplastic or absent parathyroid glands. To our knowledge, there are no reported cases of PAX1-associated hypoparathyroidism in humans. We present a case of hypoparathyroidism in a 23-month-old boy with a homozygous pathogenic variant in the PAX1 gene (PAX1 NM_006192.5 c.463_465del variant), predicted to cause an in-frame deletion of asparagine at position 155 (p.Asn155del) of the PAX1 protein. The hypoparathyroidism was unmasked after the patient developed significant hypocalcemia while receiving GoLYTELY (polyethylene glycol 3350, sodium sulfate anhydrous, sodium bicarbonate, sodium chloride, potassium chloride) for bowel cleanout. The patient had mild and asymptomatic hypocalcemia prior to hospitalization. The patient was noted to have inappropriately normal parathyroid hormone (PTH) level at the time of documented hypocalcemia thereby suggesting a diagnosis of hypoparathyroidism.

Plain language summary

The first human case of hypoparathyroidism associated with a rare genetic disorder: a case report of PAX1 gene mutation The paired box (PAX) gene family is important for embryo development. One subfamily, PAX1, is necessary for development of the spinal column, thymus (important for the immune system development), and parathyroid (helps regulate the amount of calcium in the body). We present the case of a 23-month-old boy with known PAX1 gene mutation who came in with episodes of vomiting and poor growth. His presentation was thought to be most likely related to constipation. He was started on bowel cleanout medication and intravenous fluids. However, his calcium that had been mildly low subsequently dropped to very low levels. The level of parathyroid hormone (which helps regulate calcium levels) was inappropriately normal, meaning that his body was unable to make more, and was consistent with hypoparathyroidism. He was treated with calcium supplements and vitamin D and calcium levels normalized. He continues to be on calcium and vitamin D and calcium levels have remained stable. Doctors should keep this complication in mind when treating patients with PAX1 gene mutation.

Complications, Symptoms, Presurgical Predictors in Patients With Chronic Hypoparathyroidism: A Systematic Review

The complications and symptoms of hypoparathyroidism remain incompletely defined. Measuring serum parathyroid hormone (PTH) and calcium levels early after total thyroidectomy may predict the development of chronic hypoparathyroidism. The study aimed (i) to identify symptoms and complications associated with chronic hypoparathyroidism and determine the prevalence of those symptoms and complications (Part I), and (ii) to examine the utility of early postoperative measurements of PTH and calcium in predicting chronic hypoparathyroidism (Part II). We searched Medline, Medline In-Process, EMBASE, and Cochrane CENTRAL to identify complications and symptoms associated with chronic hypoparathyroidism. We used two predefined criteria (at least three studies reported the complication and symptom and had statistically significantly greater pooled relative estimates). To estimate prevalence, we used the median and interquartile range (IQR) of the studies reporting complications and symptoms. For testing the predictive values of early postoperative measurements of PTH and calcium, we used a bivariate model to perform diagnostic test meta-analysis. In Part I, the 93 eligible studies enrolled a total of 18,973 patients and reported on 170 complications and symptoms. We identified nine most common complications or symptoms probably associated with chronic hypoparathyroidism. The complications or symptoms and the prevalence are as follows: nephrocalcinosis/nephrolithiasis (median prevalence among all studies 15%), renal insufficiency (12%), cataract (17%), seizures (11%), arrhythmia (7%), ischemic heart disease (7%), depression (9%), infection (11%), and all-cause mortality (6%). In Part II, 18 studies with 4325 patients proved eligible. For PTH measurement, regarding the posttest probability, PTH values above 10 pg/mL 12-24 hours postsurgery virtually exclude chronic hypoparathyroidism irrespective of pretest probability (100%). When PTH values are below 10 pg/mL, posttest probabilities range from 3% to 64%. Nine complications and symptoms are probably associated with chronic hypoparathyroidism. A PTH value above a threshold of 10 pg/mL 12-24 hours after total thyroidectomy is a strong predictor that the patients will not develop chronic hypoparathyroidism. Patients with PTH values below the threshold need careful monitoring as some will develop chronic hypoparathyroidism. © 2022 American Society for Bone and Mineral Research (ASBMR).

Epidemiology and Financial Burden of Adult Chronic Hypoparathyroidism

Chronic hypoparathyroidism is characterized by low serum calcium, increased serum phosphorus, and inappropriately low or decreased serum parathyroid hormone. This rare disorder is associated with a variety of complications. The prevalence, incidence, mortality, financial burden, and epidemiology of complications of this disorder are not well understood. This narrative review summarizes current information on the epidemiology and complications of chronic hypoparathyroidism. The reported prevalence of chronic hypoparathyroidism ranges from 6.4-37/100,000, and the incidence is reported to be 0.8-2.3/100,000/year. Mortality is not increased in studies from Denmark or South Korea but was increased in studies from Scotland and Sweden. The financial burden of this disorder is substantial because of increased health care resource utilization in two studies but not well quantitated. Recognized complications include hypercalciuria, nephrocalcinosis, kidney stones, and chronic kidney disease; low bone turnover and possibly upper extremity fractures; cardiac and vascular calcifications; basal ganglia calcifications, cataracts, infections, neuropsychiatric complications, and difficulties with pregnancy. This review concludes that chronic hypoparathyroidism is a rare disorder associated with significant morbidity that may not increase overall mortality but is associated with a substantial financial burden. © 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).

Etiology and Pathophysiology of Hypoparathyroidism: A Narrative Review

The approach utilized a systematic review of the medical literature executed with specifically designed criteria that focused on the etiologies and pathogenesis of hypoparathyroidism. Enhanced attention by endocrine surgeons to new knowledge about parathyroid gland viability are reviewed along with the role of intraoperative parathyroid hormone (ioPTH) monitoring during and after neck surgery. Nonsurgical etiologies account for a significant proportion of cases of hypoparathyroidism (~25%), and among them, genetic etiologies are key. Given the pervasive nature of PTH deficiency across multiple organ systems, a detailed review of the skeletal, renal, neuromuscular, and ocular complications is provided. The burden of illness on affected patients and their caregivers contributes to reduced quality of life and social costs for this chronic endocrinopathy. © 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).

Vertebral fractures, trabecular bone score and their determinants in chronic hypoparathyroidism

PURPOSE

Patients with hypoparathyroidism are at risk of vertebral fractures (VFs) despite high bone mineral density (BMD). We investigated this paradox by assessing trabecular bone score (TBS) and hip structural analysis (HSA) in non-surgical chronic hypoparathyroidism (cHypoPT) with and without VFs.

METHODS

152 cHypoPT patients (age 40.2 ± 13.4 years, M: F = 81:71) with a median follow-up of 8 (2-13) years were assessed for BMD, VFs, TBS, and HSA and compared with 152 healthy controls. VFs at T₇-L₄ were assessed by Genant's method. Average serum total calcium and phosphorus during follow-up were assessed.

RESULTS

The lumbar spine and hip BMD were higher by 25.4 and 13.4% in cHypoPT than controls (P < 0.001). Paradoxically, VFs (30.9 vs.7.9%), including multiple (12.5 vs. 2.6%) were higher in cHypoPT (P < 0.001). Though overall average TBS (1.411 ± 0.091) was normal in cHypoPT, 25.4% of the females had subnormal TBS, more in post than pre-menopausal women (52.3 vs. 14%, P = 0.002) and as compared to males (6.1%, P = 0.001). TBS correlated with menopausal status and follow-up serum calcium-phosphorus product. For every gm/cm² rise in BMD, TBS increase was only 0.227 in cHypoPT compared to 0.513 in controls. Frequency of VFs increased with declining TBS (P = 0.004). HSA was comparable between cHypoPT with and without VFs. 23.4% of cHypoPT with VFs had subnormal TBS.

CONCLUSION

31% of cHypoPT patients had VFs. TBS indicated degraded bone microarchitecture in 50% of the post-menopausal cHypoPT women. However, TBS has limitations to detect abnormal bone microarchitecture in cHypoPT as only one-fourth of patients with VFs showed low TBS.

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).

European Expert Consensus on Practical Management of Specific Aspects of Parathyroid Disorders in Adults and in Pregnancy: Recommendations of the ESE Educational Program of Parathyroid Disorders

This European expert consensus statement provides recommendations for the diagnosis and management of primary hyperparathyroidism (PHPT), chronic hypoparathyroidism in adults (HypoPT), and parathyroid disorders in relation to pregnancy and lactation. Specified areas of interest and unmet needs identified by experts at the second ESE Educational Program of Parathyroid Disorders (PARAT) in 2019, were discussed during two virtual workshops in 2021, and subsequently developed by working groups with interest in the specified areas. PHPT is a common endocrine disease. However, its differential diagnosing to familial hypocalciuric hypercalcemia (FHH), the definition and clinical course of normocalcemic PHPT, and the optimal management of its recurrence after surgery represent areas of uncertainty requiring clarifications. HypoPT is an orphan disease characterized by low calcium concentrations due to insufficient PTH secretion, most often secondary to neck surgery. Prevention and prediction of surgical injury to the parathyroid glands are essential to limit the disease-related burden. Long-term treatment modalities including the place for PTH replacement therapy and the optimal biochemical monitoring and imaging surveillance for complications to treatment in chronic HypoPT, need to be refined. The physiological changes in calcium metabolism occurring during pregnancy and lactation modify the clinical presentation and management of parathyroid disorders in these periods of life. Modern interdisciplinary approaches to PHPT and HypoPT in pregnant and lactating women and their newborns children are proposed. The recommendations on clinical management presented here will serve as background for further educational material aimed for a broader clinical audience, and were developed with focus on endocrinologists in training.

Alfacalcidol vs Calcitriol in the Management of Patient With Hypoparathyroidism: A Randomized Controlled Trial

CONTEXT

Alfacalcidol and calcitriol are commonly used for managing hypoparathyroidism. Their relative merits have not been systematically assessed.

OBJECTIVE

We compared the effect of alfacalcidol and calcitriol on phosphatemic control, hypercalciuria, and associated factors in idiopathic-hypoparathyroidism (IH).

DESIGN AND SETTING

Open-label randomized controlled trial, tertiary care center.

SUBJECTS AND METHODS

IH patients with optimal calcemic control on alfacalcidol were continued on the same (n = 20) or switched to calcitriol (n = 25) at half of the ongoing alfacalcidol dose. The dose was adjusted during follow-up to maintain serum total calcium between 8.0 and 9.5 mg/dL. Serum calcium, phosphorus, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, 24-h urine calcium-to-creatinine ratio, and fractional excretion of phosphorus (FEPh) were measured at baseline and 6 months. Plasma intact-FGF23 was measured at final follow-up.

RESULT

Patients receiving alfacalcidol and calcitriol had comparable serum calcium at 6 months (8.7 ± 0.4 vs 8.9 ± 0.4 mg/dL, P = 0.13). Their median [interquartile range (IQR)] dose at 6 months was 2.0 (1.0-2.5) and 0.75 (0.5-1.0) µg/d, respectively. Serum 1,25(OH)2D levels were physiological in both (35.3 ± 11.6 and 32.3 ± 16.9 pg/mL). Serum phosphate and calcium excretion were comparable in 2 arms. A majority had hyperphosphatemia (75% vs 76%), hypercalciuria (75% vs 72%), and elevated FGF23 (116 ± 68 and 113 ± 57 pg/mL). Age showed significant independent association with plasma FGF23 (β = 1.9, P = 0.001). Average FEPh was low despite high FGF23.

CONCLUSION

At optimal calcium control, both alfacalcidol and calcitriol lead to comparable but high serum phosphate levels, hypercalciuria, physiological circulating 1,25(OH)2D, and elevated FGF23. Further studies are required to systematically investigate other treatment options.

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.

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.