Increased mortality and morbidity in mild primary hyperparathyroid patients. The Parathyroid Epidemiology and Audit Research Study (PEARS)

Corticosteroid rhythms in hypoparathyroid patients

OBJECTIVE

Previous studies indicate a possible bidirectional stimulatory relationship between parathyroid hormone (PTH) and adrenocortical hormones, but the pattern of adrenocortical secretion in hypoparathyroidism is unknown. We aimed to characterize the adrenocortical secretion in patients with postsurgical hypoparathyroidism, and whether continuous subcutaneous PTH (1-34) infusion alters secretion patterns.

DESIGN

Crossover interventional study.

METHODS

We recruited 10 patients with postsurgical hypoparathyroidism with very low PTH levels on stable treatment with active vitamin D and calcium. Cortisol, cortisone, and aldosterone levels were measured in microdialysate from subcutaneous tissue over 24 h, before and during continuous subcutaneous PTH (1-34) infusion. Cortisol was also assayed in serum, saliva, and urine, and aldosterone and ACTH in serum and plasma, respectively. Ten patients with primary hyperparathyroidism and 10 healthy volunteers matched for sex and age served as controls.

RESULTS

Hypoparathyroid patients displayed both ultradian and circadian rhythmicity for tissue cortisol, cortisone, and aldosterone. Tissue aldosterone and cortisone levels were significantly lower in hypoparathyroid patients than in healthy controls, with no difference in tissue cortisol, but a higher cortisol to cortisone ratio. Treatment with PTH (1-34) increased tissue levels of aldosterone, cortisol, and cortisone and reduced the ratio of cortisol to cortisone.

CONCLUSION

Adrenocortical hormone levels are reduced in postsurgical hypoparathyroidism, and partly restored by short-term continuous subcutaneous PTH (1-34) therapy.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02986607.

Association between primary hyperparathyroidism and cardiovascular outcomes: A systematic review and meta-analysis

BACKGROUND

Excess parathyroid hormone (PTH) is associated with an increased risk of cardiovascular disease (CVD).

PURPOSE

We aimed to evaluate the correlation between primary hyperparathyroidism (PHPT) and CVD or cardiovascular (CV) death.

DATA SOURCES

Comprehensive searches of PubMed, Embase and ClinicalTrials.gov until May 20, 2023 with the following keywords: "primary hyperparathyroidism," "cardiovascular disease," and "mortality."

STUDY SELECTIONS

Cohort studies and randomized controlled trials comparing PHPT patients to the general population and those who had received parathyroidectomy (PTX) to those who did not.

DATA EXTRACTION

Three investigators independently extracted data and assessed study quality.

DATA SYNTHESIS

Eleven cohort studies and one randomized controlled trial were identified, including 264,227 PHPT patients with or without PTX, and the average age reported in the studies was 62 years. PHPT was associated with a higher risk of total death (RR 1.39 [95 % confidence interval (CI) 1.23-1.57) and CV death (RR 1.61 [95 % CI 1.47-1.78]) than the general population. However, there was no significant difference in CVD risk between patients with PHPT and the general population (RR 1.73 [95 % CI 0.87-3.47]). When compared to patients without PTX, PTX had a lower risk of CV death (RR 0.75 [95 % CI 0.71-0.80]), total death (RR 0.64 [95 % CI 0.60-0.70]) and CVD (RR 0.92 [95 % CI 0.90-0.94]).

LIMITATION

High heterogeneity among the included articles, and most of them were retrospective and older studies.

CONCLUSIONS

PHPT was associated with higher risk of total death and CV death while PTX was associated with lower risk of total death, CV death, and CVD.

Parathyroid hormone-PTH1R signaling in cardiovascular disease and homeostasis

Primary hyperparathyroidism (pHPT) afflicts our aging population with an incidence approaching 50 per 100 000 patient-years at a female:male ratio of ~3:1. Decisions surrounding surgical management are currently driven by age, hypercalcemia severity, presence of osteoporosis, renal insufficiency, or hypercalciuria with or without nephrolithiasis. Cardiovascular (CV) disease (CVD) is not systematically considered. This is notable since the parathyroid hormone (PTH) 1 receptor (PTH1R) is biologically active in the vasculature, and adjusted CV mortality risk is increased almost threefold in individuals with pHPT who do not meet contemporary recommendations for surgical cure. We provide an overview of epidemiology, pharmacology, and physiology that highlights the need to: (i) identify biomarkers that establish a healthy 'set point' for CV PTH1R signaling tone; (ii) better understand the pharmacokinetic-pharmacodynamic (PK-PD) relationships of PTH1R ligands in CV homeostasis; and (iii) incorporate CVD risk assessment into the management of hyperparathyroidism.

Risk of Malignant Neoplasm in Patients with Primary Hyperparathyroidism: A Systematic Review and Meta-analysis

This study aimed to evaluate the prevalence and risk of malignant neoplasm in primary hyperparathyroidism (PHPT) patients. Potentially eligible studies were retrieved from PubMed and Embase databases from inception to November 2023 using search strategy consisting of terms for "Primary hyperparathyroidism" and "Malignant neoplasm". Eligible study must report prevalence of malignant neoplasm among patients with PHPT or compare the risk of malignant neoplasm between patients with PHPT and comparators. Point estimates with standard errors were extracted from each study and combined using the generic inverse variance method.A total of 11,926 articles were identified. After two rounds of systematic review, 50 studies were included. The meta-analysis revealed that pooled prevalence rates of overall cancer was 0.19 (95%CI: 0.13-0.25; I2 94%). The two most prevalent types of malignancy among patients with PHPT ware papillary thyroid cancer (pooled prevalence: 0.07; 95%CI: 0.06-0.08; I2 85%) and breast cancer (pooled prevalence: 0.05; 95%CI: 0.03-0.07; I2 87%). Subgroup analysis of studies focusing on patients undergoing parathyroidectomy reported a fourfold higher prevalence of papillary thyroid cancer than the remaining studies (0.08 versus 0.02). The meta-analysis of cohort studies found a significant association between PHPT and overall cancer with the pooled risk ratio of 1.28 (95%CI: 1.23-1.33; I2 66.9%).We found that the pooled prevalence of malignant neoplasm in PHPT was 19%, with papillary thyroid cancer and breast cancer being the most prevalent types. The meta-analysis of cohort studies showed that patient with PHPT carried an approximately 28% increased risk of malignancy.

Testing for Primary Hyperparathyroidism in 17,491 Patients With Hypercalcemia

BACKGROUND

Primary hyperparathyroidism (PHPT) is underdiagnosed and associated with many adverse health effects. Historically, many hypercalcemic patients have not received parathyroid hormone (PTH) testing; however, underlying reasons are uncertain. Our goals are to determine the PTH testing rate among hypercalcemic individuals at a large academic health system and to assess for characteristics associated with testing versus not testing for PHPT to inform future strategies for closing testing gaps.

METHODS

This retrospective study included adult patients with ≥1 elevated serum calcium result between 2018 and 2022. Based on the presence or absence of a serum PTH result, individuals were classified as "screened" versus "unscreened" for PHPT. Demographic and clinical characteristics of these groups were compared.

RESULTS

The sample comprised 17,491 patients: 6567 male (37.5%), 10,924 female (62.5%), mean age 59 y. PTH testing was performed in 6096 (34.9%). Characteristics independently associated with the greatest odds of screening were 5+ elevated calcium results (odds ratio [OR] 5.02, P < 0.0001), chronic kidney disease (OR 3.63, P < 0.0001), maximum calcium >12.0 mg/dL (OR 2.48, P < 0.0001), and osteoporosis (OR 2.42, P < 0.0001). Characteristics associated with lowest odds of screening were age <35 y (OR 0.60, P < 0.0001), death during the study period (OR 0.68, P < 0.0001), age ≥85 y (OR 0.70, P = 0.0007), and depression (OR 0.84; P = 0.0081).

CONCLUSIONS

Only 35% of hypercalcemic patients received PTH testing. Although the presence of PHPT-associated morbidity was generally associated with increased rates of screening, hypercalcemic patients with depression were 16% less likely to be tested.

Renal Dysfunction in Primary Hyperparathyroidism is associated with nephrolithiasis, elevated serum calcium-phosphate product and parathormone levels

PURPOSE

Baseline renal dysfunction predicts mortality in primary hyperparathyroidism (PHPT). However, it remains controversial whether renal insufficiency in PHPT is due to disease severity alone or other risk factors. This study aimed to explore the association of clinico-biochemical variables with renal dysfunction [estimated glomerular filtration rate (eGFR) < 60 ml/min/m2] in PHPT.

METHODS

A total of 112 patients of PHPT were selected and divided into following subgroups: renal dysfunction (n = 28) and normal renal function (n = 84). Demographic characteristics, traditional risk factors, phenotypes of PHPT based on target organ involvement, and biochemical parameters were compared between these subgroups.

RESULTS

Patient subgroups of PHPT with and without renal dysfunction had similar age, frequency of diabetes, and hypertension. Renal dysfunction was more prevalent in males (p < 0.05). Compared to normal renal function subgroup, individuals with renal dysfunction had higher serum levels of calcium, phosphate, alkaline phosphatase, intact parathormone (all p < 0.05), while having lower hemoglobin levels (p < 0.05) and higher nephrolithiasis rates (p < 0.05). Multiple regression analysis revealed that nephrolithiasis, serum calcium-phosphorous product (CaxP), parathormone levels were positively associated with baseline renal dysfunction (all p < 0.01). A baseline PTH > 456 pg/mL and CaxP > 30.0 mg2/dl2 could discriminate renal dysfunction from normal renal function with sensitivity and specificity of 75% and 74.5% and 92.6% and 74.4%, respectively.

CONCLUSION

Renal dysfunction was associated with presence of nephrolithiasis, elevated serum CaxP and PTH levels in our cohort with predominantly symptomatic PHPT, indicating an association with the underlying disease itself. Serum CaxP may additionally be appraised during risk assessment in PHPT.

Evaluating the clinical and mechanistic effects of eplerenone and amiloride monotherapy, and combination therapy with cinacalcet, in primary hyperparathyroidism: A placebo-controlled randomized trial

OBJECTIVES

Human physiology and epidemiology studies have demonstrated complex interactions between the renin-angiotensin-aldosterone system, parathyroid hormone and calcium homeostasis. Several of these studies have suggested that aldosterone inhibition may lower parathyroid hormone (PTH) levels. The objective of this study was to assess the effect of 4 weeks of maximally tolerated mineralocorticoid receptor antagonist therapy with eplerenone on PTH levels in patients with primary hyperparathyroidism (P-HPT) when compared to amiloride and placebo. We also investigated the synergistic effect of these interventions when combined with cinacalcet for an additional 2 weeks.

DESIGN

Randomized, double-blinded, three parallel-group, placebo-controlled trial.

PATIENTS

Patients with P-HPT.

RESULTS

Most patients were women (83%) and White (76%). Maximally tolerated doses of eplerenone and amiloride induced significant reductions in blood pressure and increases in renin and aldosterone production; however, despite these physiologic changes, neither intervention induced significant changes in PTH or calcium levels when compared to the placebo. Both eplerenone and amiloride therapy induced significant reductions in procollagen type 1 N-terminal propeptide levels when compared to placebo. When cinacalcet therapy was added, PTH and calcium levels were markedly reduced in all groups; however, there was no significant difference in PTH or serum calcium reductions between groups.

CONCLUSIONS

Although maximally tolerated therapy with eplerenone and amiloride induced expected changes in renin, aldosterone and blood pressure, there were no meaningful changes in PTH or serum calcium levels in P-HPT patients. These results suggest that inhibition of aldosterone action does not have a clinically meaningful role in medical therapy for P-HPT.

Revisiting Age Criterion for Surgery in Asymptomatic Primary Hyperparathyroidism

OBJECTIVE

To revisit the current age criterion (50 years) for surgical candidacy in patients diagnosed with asymptomatic primary hyperparathyroidism (PHPT).

STUDY DESIGN

A predictive model relying on past publications using the electronic databases "PubMed," "Embase," "Medline," and "Google Scholar."

SETTING

Hypothetical large cohort.

METHODS

A Markov model was constructed, based on relevant literature, to compare 2 potential treatment algorithms for asymptomatic PHPT patients, parathyroidectomy (PTX), and observation. The various potential health states were characterized for the 2 treatment options and included potential surgical complications, end-organ deterioration, and death. A 1-way sensitivity analysis was performed to calculate the quality-adjusted life year (QALY) gains of both strategies. A Monte-Carlo simulation for 30,000 subjects was performed and cycled per annum.

RESULTS

On the basis of the model's assumptions, the QALY value for the PTX strategy was 19.17 versus 17.82 for the observation strategy. The incremental QALY gains for various ages according to the sensitivity analyses for PTX in comparison to observation were: 2.84 QALY for 40-year-old patients, 2.2 QALY for 50-year-old patients, 1.81 QALY for 55-year-old patients, 1.35 QALY for 60-year-old patients, and 0.86 QALY for 65-year-old patients. The incremental QALY is below 0.5 after the age of 75 years.

CONCLUSION

This study found PTX to be advantageous for asymptomatic PHPT patients older than the current age criterion of 50 years. The calculated QALY gains support a surgical approach for medically fit patients in their 50s. The current guidelines for the surgical treatment of young asymptomatic PHPT patients should be revisited by the next steering committee.

Analysis of Comorbidities, Clinical Outcomes, and Parathyroidectomy in Adults With Primary Hyperparathyroidism

Importance

Patients with primary hyperparathyroidism (pHPT) appear to have an increased risk of fractures and other comorbidities, such as cardiovascular disease, although results from previous studies have been inconsistent. Evidence of the association of parathyroidectomy (PTX) with these outcomes is also limited because of the lack of large well-controlled trials.

Objective

To investigate whether untreated pHPT was associated with an increased risk of incident fractures and cardiovascular events (CVEs) and whether PTX was associated with a reduced risk of these outcomes.

Design, Setting, and Participants

This cohort study included all patients who were diagnosed with pHPT at hospitals in Sweden between July 1, 2006, and December 31, 2017. Each patient was matched with 10 control individuals from the general population by sex, birth year, and county of residence. The patients were followed up until December 31, 2017. Data analyses were performed from October 2021 to April 2022.

Main Outcomes and Measures

The primary outcomes were fractures, CVEs, and death. Cumulative incidence of events was estimated using the 1-minus Kaplan-Meier estimator of corresponding survival function. Cox proportional hazards regression models were used to calculate hazard ratios (HRs).

Results

A total of 16 374 patients with pHPT were identified (mean [SD] age, 67.5 [12.9] years; 12 806 women [78.2%]), with 163 740 control individuals. The follow-up time was 42 310 person-years for the pHPT group and 803 522 person-years for the control group. Compared with the control group, the pHPT group had a higher risk of any fracture (unadjusted HR, 1.39; 95% CI, 1.31-1.48), hip fracture (unadjusted HR, 1.51; 95% CI, 1.35-1.70), CVEs (unadjusted HR, 1.45; 95% CI, 1.34-1.57), and death (unadjusted HR, 1.72; 95% CI, 1.65-1.80). In a time-dependent Poisson regression model, PTX was associated with a reduced risk of any fracture (HR, 0.83; 95% CI, 0.75-0.93), hip fracture (HR, 0.78; 95% CI, 0.61-0.98), CVEs (HR, 0.84; 95% CI, 0.73-0.97), and death (HR, 0.59; 95% CI, 0.53-0.65).

Conclusions and Relevance

Results of this study suggest that pHPT is associated with increased risk of fractures, CVEs, and death, highlighting the importance of identifying patients with this condition to prevent serious unfavorable outcomes. The reduced risk of these outcomes associated with PTX suggests a clinical benefit of surgery.

Effect of Parathyroidectomy on Metabolic Homeostasis in Primary Hyperparathyroidism

Background: The benefits of parathyroidectomy on cardiovascular risk in primary hyperparathyroidism (PHPT) are controversial. This monocentric, observational, prospective study aimed to assess the effects of parathyroidectomy on glucose and lipid metabolism in classic or mild PHPT. Methods: Patients who underwent parathyroidectomy for classic (calcemia >2.85 mmol/L) or mild PHPT (calcemia ≤2.85 mmol/L) between 2016 and 2019 were included. A metabolic assessment was performed before and 1 year after parathyroidectomy. Patients with a history of diabetes were excluded. Results: Nineteen patients had classic and 120 had mild PHPT. Ninety-five percent were normocalcemic 6 months after surgery. Fasting plasma glucose and insulin levels decreased after parathyroidectomy in patients with mild PHPT (p < 0.001). HOMA-IR decreased after surgery in the overall population (p < 0.001), while plasma adiponectin concentrations increased in patients with both classic (p = 0.005) and mild PHPT (p < 0.001). Plasma triglyceride levels decreased significantly only in patients with classic PHPT (p = 0.021). Plasma PCSK9 levels decreased in patients with mild PHPT (p < 0.001). Conclusions: Parathyroidectomy for PHPT improves insulin resistance and decreases plasma triglyceride levels in classic PHPT and plasma PCSK9 levels in mild PHPT. Further studies are needed to better characterize the consequences of such metabolic risk factors’ improvements on cardiovascular events.

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.

Primary Hyperparathyroidism: A Narrative Review of Diagnosis and Medical Management

Primary hyperparathyroidism (PHPT) is the most common cause of hypercalcemia in the outpatient setting. Symptomatic presentation includes non-specific signs and symptoms of hypercalcemia, skeletal fragility, nephrolithiasis and nephrocalcinosis. The majority of individuals present at an asymptomatic stage following routine biochemical screening, without any signs or symptoms of calcium or parathyroid hormone (PTH) excess or target organ damage. Indications for surgery have recently been revised as published in recent guidelines and consensus statements. Parathyroidectomy is advised in patients younger than 50 years old and in the presence of either significant hypercalcemia, impaired renal function, renal stones or osteoporosis. Surgery is always appropriate in suitable surgical candidates, however, medical management may be considered in those with mild asymptomatic disease, contraindications to surgery or failed previous surgical intervention. We summarized the optimal medical interventions available in the care of PHPT patients not undergoing parathyroidectomy. Calcium and vitamin D intake should be optimized. Antiresorptive therapy may be used for skeletal protection in patients with an increased fracture risk. Cinacalcet, a calcimimetic agent, has been shown to effectively lower serum calcium and PTH levels. The effect of medical treatment on the reduction in fracture risk is unknown and should be the focus of future research.

Primary Aldosteronism with Parathyroid Hormone Elevation: A Single-center Retrospective Study

Objective Primary aldosteronism (PA) is a major cause of secondary hypertension. The association between PA and other hormone disorders is unclear. The present study aimed to evaluate whether the parathyroid hormone (PTH) value is associated with PA subtypes or specific treatments. Methods We enrolled 135 patients with PA who had their PTH value measured before undergoing a specific treatment. We evaluated whether PTH value is associated with PA subtypes or with specific treatments. The present study is a single-center retrospective study (2011-2018). Results Our study showed that, among the patients with PA, the proportion of those with PTH elevation was >30%. The PTH value was significantly correlated with both the basal plasma aldosterone concentration (PAC) and PAC after a captopril challenge test. However, the PTH value was not significantly different between the patients with unilateral and bilateral PA. We observed that the serum PTH value decreased after treatment of PA with unilateral adrenalectomy or mineralocorticoid receptor antagonists. Conclusion Our findings suggest that the PTH value in PA patients might be associated with the autonomous production of aldosterone. However, there was no correlation between the PTH value and PA subtypes in our study. Additionally, our study showed that targeted treatment for PA may lead to a decrease in the serum PTH levels. Hence, the PTH value could potentially be used as an index for measuring the suitability for PA treatment.

Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism

Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.

PTH/PTHrP Receptor Signaling Restricts Arterial Fibrosis in Diabetic LDLR-/- Mice by Inhibiting Myocardin-Related Transcription Factor Relays

RATIONALE

The PTH1R (PTH [parathyroid hormone]/PTHrP [PTH-related protein] receptor) is expressed in vascular smooth muscle (VSM) and increased VSM PTH1R signaling mitigates diet-induced arteriosclerosis in LDLR-/- mice.

OBJECTIVE

To study the impact of VSM PTH1R deficiency, we generated mice SM22-Cre:PTH1R(fl/fl);LDLR-/- mice (PTH1R-VKO) and Cre-negative controls.

METHODS AND RESULTS

Immunofluorescence and Western blot confirmed PTH1R expression in arterial VSM that was reduced by Cre-mediated knockout. PTH1R-VKO cohorts exhibited increased aortic collagen accumulation in vivo, and VSM cultures from PTH1R-VKO mice elaborated more collagen (2.5-fold; P=0.01) with elevated Col3a1 and Col1a1 expression. To better understand these profibrotic responses, we performed mass spectrometry on nuclear proteins extracted from Cre-negative controls and PTH1R-VKO VSM. PTH1R deficiency reduced Gata6 but upregulated the MADS (MCM1, Agamous, Deficiens, and Srf DNA-binding domain)-box transcriptional co-regulator, Mkl-1 (megakaryoblastic leukemia [translocation] 1). Co-transfection assays (Col3a1 promoter-luciferase reporter) confirmed PTH1R-mediated inhibition and Mkl-1-mediated activation of Col3a1 transcription. Regulation mapped to a conserved hybrid CT(A/T)6GG MADS-box cognate in the Col3a1 promoter. Mutations of C/G in this motif markedly reduced Col3a1 transcriptional regulation by PTH1R and Mkl-1. Upregulation of Col3a1 and Col1a1 in PTH1R-VKO VSM was inhibited by small interfering RNA targeting Mkl1 and by treatment with the Mkl-1 antagonist CCG1423 or the Rock (Rho-associated coiled-coil containing protein kinase)-2 inhibitor KD025. Chromatin precipitation demonstrated that VSM PTH1R deficiency increased Mkl-1 binding to Col3a1 and Col1a1, but not TNF, promoters. Proteomic studies of plasma extracellular vesicles and VSM from PTH1R-VKO mice identified C1r (complement component 1, r) and C1s (complement component 1, s), complement proteins involved in vascular collagen metabolism, as potential biomarkers. VSM C1r protein and C1r message were increased with PTH1R deficiency, mediated by Mkl-1-dependent transcription and inhibited by CCG1423 or KD025.

CONCLUSIONS

PTH1R signaling restricts collagen production in the VSM lineage, in part, via Mkl-1 regulatory circuits that control collagen gene transcription. Strategies that maintain homeostatic VSM PTH1R signaling, as reflected in extracellular vesicle biomarkers of VSM PTH1R/Mkl-1 action, may help mitigate arteriosclerosis and vascular fibrosis.

Primary hyperparathyroidism and hypertension

Although untreated primary hyperparathyroidism is associated with increased cardiovascular mortality, controversy exists regarding the therapeutic effects of parathyroidectomy on cardiovascular health. This review will examine the evidence linking primary hyperparathyroidism (PHPT) and cardiovascular disease, specifically hypertension, and evaluate the available literature regarding the natural history of hypertension after successful parathyroidectomy.

The effect of parathyroidectomy on bone mineral density in primary hyperparathyroidism

Background/aim

This study aimed to investigate the change in bone mineral density (BMD) before and 1 year after parathyroidectomy in patients with primary hyperparathyroidism (PHPT).

Materials and methods

The clinical and biochemical parameters and DEXA screening of patients with symptomatic PHPT (n = 28) and asymptomatic PHPT (n = 63) were investigated before and 1 year after parathyroidectomy.

Results

Patients with symptomatic PHPT had a higher prevalence of nephrolithiasis (18.2% vs. 4.6%, P = 0.032) when compared to the prevalence in patients with asymptomatic PHPT. The prevalence of osteoporosis in the lumbar spine (63.0% vs. 37.5%, P = 0.026) and femoral neck (40.7% vs. 20.6%, P = 0.048) was higher in symptomatic PHPT when compared to the prevalence in asymptomatic PHPT. After parathyroidectomy, the decreases in the prevalence of osteoporosis in the lumbar spine (25.8% vs. 9.4%, P = 0.014), femoral neck (22.1% vs. 8.2%, P =0.009), and total hip (22.4% vs. 5.3%, P = 0.007) were higher in symptomatic PHPT compared to the asymptomatic PHPT group. A higher BMD gain (g/cm2) was seen in the lumbar spine (10.83% vs. 4.65%, P=0.016) and femoral neck (12.61% vs. 4.37%, P=0.005) in symptomatic PHPT compared to the asymptomatic PHPT group.

Conclusion

Parathyroidectomy provided more BMD gain in the lumbar spine and femoral neck in patients with symptomatic PHPT when compared to patients with asymptomatic PHPT 1 year after parathyroidectomy.

Vitamin D status and cardiovascular outcome

INTRODUCTION

Vitamin D is classically involved in maintaining bone and mineral health, but it has been shown to exert many extraskeletal functions, including pleiotropic effects on cardiovascular system.

MATERIALS AND METHOD

This review aims to summarize evidences in literature about vitamin D and cardiovascular outcome.

RESULTS AND CONCLUSIONS

Calcitriol or 1,25(OH)₂D, the active hormone, binds to the specific nuclear receptor VDR, which is expressed in rat and human heart and vasculature and has effects on myocardiocytes, smooth cells, and endothelial cells. 25-Hydroxy-vitamin D (25OHD) represents the biomarker of vitamin D levels and reflects vitamin D status. There is consistent evidence that low serum 25OHD levels are associated with increased risk of cardiovascular diseases, including hypertension, coronary artery disease, ischemic heart disease, heart failure, stroke, and type 2 diabetes. Randomized-controlled trials and Mendelian randomization studies so far have not succeeded in proving a benefit of vitamin D supplementation. However, the latter investigations are affected by some methodological limitations, and therefore, it is still unclear if vitamin D deficiency has a causative role in cardiovascular diseases or is rather a marker of poor health in chronic disease.

Effect of parathyroidectomy on epicardial fat thickness as a cardiovascular risk factor in patients with primary hyperparathyroidism

Background/aim

Several studies demonstrated that primary hyperparathyroidism is related to increased risk for cardiovascular diseases (CVDs), and risk is decreased by parathyroidectomy. Epicardial fat thickness (EFT) has been postulated as a new marker of CVD risk. We evaluated the impact of parathyroidectomy on EFT in patients with primary hyperparathyroidism (PHPT).

Materials and methods

Thirty-four PHPT patients (29 female, 5 male) and 28 age- and sex-matched controls (19 female, 9 male) were included in the study. Demographic, anthropometric, and biochemical data were recorded both before parathyroidectomy and 6 months after the procedure. Epicardial fat thickness was measured by transthoracic echocardiography.

Results

Mean age was 53.15 ± 8.44 years. Mean preoperative EFT was higher than mean EFT in the control group (0.49 ± 0.07 cm to 0.46 ± 0.08 cm, P: 0.0005), and EFT decreased after parathyroidectomy (0.49 ± 0.07 cm to 0.44 ± 0.08 cm, P: 0.0005). Systolic blood pressure and calcium, parathormone, and hsCRP levels decreased after parathyroidectomy (P < 0.05). Vitamin D levels increased (P < 0.05). Diastolic blood pressure, body mass index, carotid intima-media thickness, and HOMA-IR, fasting plasma glucose, and phosphorus levels were unchanged after parathyroidectomy (P > 0.05). Preoperatively, EFT was correlated with SBP (r: 0.360, P: 0.0285) and age (r: 0.466, P: 0.0036). Multiple linear regression used to identify independent predictors of change in epicardial fat did not find any predictor of change in epicardial fat (P > 0.05).

Conclusion

EFT was decreased by parathyroidectomy in patients with primary hyperparathyroidism.However, the decrease in EFT was not correlated with any of the cardiovascular risk factors. More comprehensive studies evaluating the potential relation between PHPT and EFT need to be conducted.

Factors associated with glomerular filtration rate variation in primary hyperparathyroidism after parathyroidectomy

Background/aim

Prolonged hypercalcemia impairs renal function, and a reduced glomerular filtration rate (GFR) is typical in advanced primary hyperparathyroidism (PHPT). There are scarce data related to predictors of renal impairment in patients with PHPT. Hence, we aimed to evaluate changes in kidney function in PHPT patients after parathyroidectomy (PTX) and identify factors associated with GFR variation in these patients.

Materials and methods

One hundred and twenty-five patients with PHPT who underwent surgery between 2012 and 2014 were enrolled in the study. Patients were divided into two groups according to GFR values: patients whose GFR was lower than 60 mL/min/1.73 m2 and higher than 60 mL/min/1.73 m2. Demographic and laboratory parameters were compared before and 6 months after parathyroidectomy.

Results

Prevalence of antihypertensive drug users and patients with renal cysts and parathormone (PTH) and alkaline phosphatase levels were higher in patients with GFR of ≥60 than in GFR of <60 mL/min/1.73 m2 (P < 0.05). Systolic BP, uric acid, and magnesium were decreased in patients with GFR of ≥60, but GFR did not change in the two groups after parathyroidectomy. After parathyroidectomy, calcium and PTH decreased but 25(OH)D3 and phosphorus increased in the two groups. In multiple regression analysis, age, calcium, and baseline GFR were independent predictors of GFR variation. Parathyroid adenoma volume and urinary calcium were not independent predictors of GFR change.

Conclusion

Older age, higher preoperative calcium, and GFR were factors associated with GFR increase in PHPT patients after parathyroidectomy. Further renal impairment was prevented by parathyroidectomy in PHPT patients.

[Current approach to the diagnosis and treatment of primary hyperparathyroidism]

AIM

To optimize diagnosis and surgical treatment of patients with primary hyperparathyroidism.

MATERIAL AND METHODS

Retrospective comparative analysis of diagnosis and surgical treatment included 444 patients who were treated at the specialized department of endocrine surgery of Pirogov National Medical Surgical Center in 2012-2017. Archival materials and electronic databases of the clinic were applied.

RESULTS

It was developed the algorithm which may be used in most patients for minimally invasive parathyroidectomy. Minimally invasive surgery reduces the risk of complications and is associated with reliable efficacy and good cosmetic effect.

Effects of Altered Calcium Metabolism on Cardiac Parameters in Primary Aldosteronism

BACKGROUND

Increasing evidence supports interplay between aldosterone and parathyroid hormone (PTH), which may aggravate cardiovascular complications in various heart diseases. Negative structural cardiovascular remodeling by primary aldosteronism (PA) is also suspected to be associated with changes in calcium levels. However, to date, few clinical studies have examined how changes in calcium and PTH levels influence cardiovascular outcomes in PA patients. Therefore, we investigated the impact of altered calcium homeostasis caused by excessive aldosterone on cardiovascular parameters in patients with PA.

METHODS

Forty-two patients (mean age 48.8±10.9 years; 1:1, male:female) whose plasma aldosterone concentration/plasma renin activity ratio was more than 30 were selected among those who had visited Severance Hospital from 2010 to 2014. All patients underwent adrenal venous sampling with complete access to both adrenal veins.

RESULTS

The prevalence of unilateral adrenal adenoma (54.8%) was similar to that of bilateral adrenal hyperplasia. Mean serum corrected calcium level was 8.9±0.3 mg/dL (range, 8.3 to 9.9). The corrected calcium level had a negative linear correlation with left ventricular end-diastolic diameter (LVEDD, ρ=-0.424, P=0.031). Moreover, multivariable regression analysis showed that the corrected calcium level was marginally associated with the LVEDD and corrected QT (QTc) interval (β=-0.366, P=0.068 and β=-0.252, P=0.070, respectively).

CONCLUSION

Aldosterone-mediated hypercalciuria and subsequent hypocalcemia may be partly involved in the development of cardiac remodeling as well as a prolonged QTc interval, in subjects with PA, thereby triggering deleterious effects on target organs additively.

Calcium and Cardiovascular Disease

Circulating calcium is a risk factor for vascular disease, a conclusion arising from prospective studies involving hundreds of thousands of participants and extending over periods of up to 30 years. These associations may be partially mediated by other cardiovascular risk factors such as circulating lipid levels, blood pressure, and body mass index, but there appears to be a residual independent effect of serum calcium. Polymorphisms of the calcium-sensing receptor associated with small elevations of serum calcium are also associated with cardiovascular disease, suggesting that calcium plays a causative role. Trials of calcium supplements in patients on dialysis and those with less severe renal failure demonstrate increased mortality and/or acceleration of vascular disease, and meta-analyses of trials in those without overt renal disease suggest a similar adverse effect. Interpretation of the latter trials is complicated by a significant interaction between baseline use of calcium supplements and the effect of randomisation to calcium in the largest trial. Restriction of analysis to those who are calcium-naive demonstrates a consistent adverse effect. Observational studies of dietary calcium do not demonstrate a consistent adverse effect on cardiovascular health, though very high or very low intakes may be deleterious. Thus, obtaining calcium from the diet rather than supplements is to be encouraged.

Relationship between bone turnover and left ventricular function in primary hyperparathyroidism: The EPATH trial

Observational studies suggested a link between bone disease and left ventricular (LV) dysfunction that may be pronounced in hyperparathyroid conditions. We therefore aimed to test the hypothesis that circulating markers of bone turnover correlate with LV function in a cohort of patients with primary hyperparathyroidism (pHPT). Cross-sectional data of 155 subjects with pHPT were analyzed who participated in the "Eplerenone in Primary Hyperparathyroidism" (EPATH) Trial. Multivariate linear regression analyses with LV ejection fraction (LVEF, systolic function) or peak early transmitral filling velocity (e', diastolic function) as dependent variables and N-terminal propeptide of procollagen type 1 (P1NP), osteocalcin (OC), bone-specific alkaline phosphatase (BALP), or beta-crosslaps (CTX) as the respective independent variable were performed. Analyses were additionally adjusted for plasma parathyroid hormone, plasma calcium, age, sex, HbA1c, body mass index, mean 24-hours systolic blood pressure, smoking status, estimated glomerular filtration rate, antihypertensive treatment, osteoporosis treatment, 25-hydroxy vitamin D and N-terminal pro-brain B-type natriuretic peptide. Independent relationships were observed between P1NP and LVEF (adjusted β-coefficient = 0.201, P = 0.035) and e' (β = 0.188, P = 0.042), respectively. OC (β = 0.192, P = 0.039) and BALP (β = 0.198, P = 0.030) were each independently related with e'. CTX showed no correlations with LVEF or e'. In conclusion, high bone formation markers were independently and paradoxically related with better LV diastolic and, partly, better systolic function, in the setting of pHPT. Potentially cardio-protective properties of stimulated bone formation in the context of hyperparathyroidism should be explored in future studies.

Skeletal changes after restoration of the euparathyroid state in patients with hypoparathyroidism and primary hyperparathyroidism

Restoration of the euparathyroid state is associated with improvement of bone dynamics both in hypoparathyroidism and primary hyperparathyroidism. To date, no study has directly compared these two groups following correction of parathyroid hormone excess or deficiency. The study was designed to investigate changes in bone mineral density and trabecular bone score with restoration of the euparathyroid state by parathyroidectomy in primary hyperparathyroidism or recombinant parathyroid hormone [rhPTH(1-84)] replacement in hypoparathyroidism. This was a 2-year prospective intervention study in which we evaluated areal bone mineral density by DXA and trabecular bone score in 52 hypoparathyroid patients on rhPTH(1-84) replacement and 27 patients with primary hyperparathyroidism who underwent parathyroidectomy. We evaluated changes in areal bone mineral density by DXA and trabecular bone score at baseline, 6, 12, 18, and 24 months. After parathyroidectomy, areal bone mineral density increased from baseline at the lumbar spine and total hip at 6 months and at the femoral neck at 12 months, while there were no changes at the distal 1/3 radius. Treatment with rhPTH(1-84) was associated with significant increases in lumbar spine and decreases in distal 1/3 radius areal bone mineral density by 18 months in hypoparathyroid patients. At this time point, hypoparathyroid subjects demonstrated a significant increase in trabecular bone score from baseline, while there were no significant changes in trabecular bone score following parathyroidectomy. Bone mineral density increases both with administration of parathyroid hormone in a state of parathyroid hormone deficiency or removal of parathyroid hormone in a state of parathyroid hormone excess. However, only hypoparathyroid patients on rhPTH(1-84) appeared to have improvements in micro-architectural pattern as assessed by trabecular bone score.

Primary hyperparathyroidism: review and recommendations on evaluation, diagnosis, and management. A Canadian and international consensus

The purpose of this review is to assess the most recent evidence in the management of primary hyperparathyroidism (PHPT) and provide updated recommendations for its evaluation, diagnosis and treatment. A Medline search of "Hyperparathyroidism. Primary" was conducted and the literature with the highest levels of evidence were reviewed and used to formulate recommendations. PHPT is a common endocrine disorder usually discovered by routine biochemical screening. PHPT is defined as hypercalcemia with increased or inappropriately normal plasma parathyroid hormone (PTH). It is most commonly seen after the age of 50 years, with women predominating by three to fourfold. In countries with routine multichannel screening, PHPT is identified earlier and may be asymptomatic. Where biochemical testing is not routine, PHPT is more likely to present with skeletal complications, or nephrolithiasis. Parathyroidectomy (PTx) is indicated for those with symptomatic disease. For asymptomatic patients, recent guidelines have recommended criteria for surgery, however PTx can also be considered in those who do not meet criteria, and prefer surgery. Non-surgical therapies are available when surgery is not appropriate. This review presents the current state of the art in the diagnosis and management of PHPT and updates the Canadian Position paper on PHPT. An overview of the impact of PHPT on the skeleton and other target organs is presented with international consensus. Differences in the international presentation of this condition are also summarized.

Diffuse parathyroid hormone expression in parathyroid tumors argues against important functional tumor subclones

OBJECTIVE

Primary hyperparathyroidism is usually characterized by a monoclonal parathyroid tumor secreting excess parathyroid hormone (PTH). The main regulator of PTH secretion is calcium and the calcium-PTH set point is shifted in parathyroid tumor cells. We sought to investigate the relationship between tumor PTH and PTH mRNA expression and clinical presentation as well as the regulatory factors including phosphate, vitamin D, and fibroblast growth factor 23.

DESIGN

A total of 154 parathyroid tumors were analyzed by PTH immunohistochemistry and chromogenic in situ hybridization of PTH mRNA. A subset of samples (n = 34) was analyzed using quantitative real-time PCR.

RESULTS

Low tumor PTH mRNA level was significantly associated with low tumor PTH immunoreactivity (P = 0.026), but the two did not correlate with regard to histological distribution within individual tumors. Tumors displaying reduced PTH mRNA levels as compared with normal rim were significantly larger (P = 0.013) and showed higher expression of the calcium-sensing receptor (CASR) (P = 0.046). Weaker tumor PTH mRNA level was significantly associated with higher concentration of circulating 25-hydroxyvitamin D (P = 0.005). No significant correlation was seen between PTH immunoreactivity and patient biochemistry. Tumor weight was strongly associated with circulatory concentrations of calcium and PTH.

CONCLUSIONS

No areas with apparently higher PTH expression were identified, perhaps suggesting that hyper functioning parathyroid tumor subclones should be rare. Circulating 25-hydroxyvitamin D levels may influence tumor PTH expression in vivo. If PTH immunoreactivity reflects the tumor calcium-PTH set point, our data imply that the main determinant of disease severity should be tumor weight.

Thiazide-Associated Hypercalcemia: Incidence and Association With Primary Hyperparathyroidism Over Two Decades

CONTEXT

Thiazide diuretics, the antihypertensive agent prescribed most frequently worldwide, are commonly associated with hypercalcemia. However, the epidemiology and clinical features are poorly understood.

OBJECTIVE

To update the incidence of thiazide-associated hypercalcemia and clarify its clinical features.

PATIENTS AND METHODS

In a population-based descriptive study, Olmsted County, Minnesota, residents with thiazide-associated hypercalcemia were identified through the Rochester Epidemiology Project and the Mayo Clinic Laboratory Information System from 2002-2010 and were added to the historical cohort beginning in 1992.

MAIN OUTCOME

Incidence rates were adjusted to the 2010 United States white population.

RESULTS

Overall, 221 Olmsted County residents were identified with thiazide-associated hypercalcemia an average of 5.2 years after initiation of treatment. Subjects were older (mean age, 67 years) and primarily women (86.4%). The incidence of thiazide-associated hypercalcemia increased after 1997 and peaked in 2006 with an annual incidence of 20 per 100,000, compared to an overall rate of 12 per 100,000 in 1992-2010. Severe hypercalcemia was not observed in the cohort despite continuation of thiazide treatment in 62.4%. Of patients discontinuing thiazides, 71% continued to have hypercalcemia. Primary hyperparathyroidism was diagnosed in 53 patients (24%), including five patients who underwent parathyroidectomy without thiazide discontinuation.

CONCLUSIONS

Many patients with thiazide-associated hypercalcemia have underlying primary hyperparathyroidism. Additionally, a sharp rise in thiazide-associated hypercalcemia incidence began in 1998, paralleling the increase observed in primary hyperparathyroidism in this community. Case ascertainment bias from targeted osteoporosis screening is the most likely explanation.

Estimated glomerular filtration rate by serum cystatin C correlates with cardiometabolic parameters in patients with primary hyperparathyroidism

OBJECTIVE

Patients with primary hyperparathyroidism (PHPT) are at risk of chronic kidney disease (CKD). Cystatin C (Cys-C) is considered a more reliable tool to assess glomerular filtration rate (GFR) than creatinine. The study aimed to assess circulating Cys-C and its relationships with biochemical PHPT and cardiometabolic parameters.

DESIGN AND METHODS

The present cross-sectional study was performed in academic endocrine units on PHPT patients (n=190) and non-hypertensive, non-diabetic, age- and sex-matched healthy controls (n=135) with no established CKD. The main outcomes were creatinine by alkaline picrate method, Cys-C by immunonephelometry and calculation of estimated GFR based on creatinine and Cys-C (eGFRcr-cys) using the CKD-EPI equation.

RESULTS

In PHPT patients, circulating Cys-C ranged 0.45-3.13  mg/l and correlated with creatinine, age and BMI. Mean Cys-C level was higher in PHPT patients than in controls (0.93±0.02 vs 0.78±0.14  mg/l; P=0.03). Cys-C levels in PHPT patients were predicted by age, BMI, ionized calcium, hypertension and HDL-cholesterol, the most significant determinant being ionized calcium. Cys-C positively correlated with cardiovascular disease (CVD) occurrence. Overall, 18.4% of PHPT patients with eGFRcr >60  ml/min per 1.73  m(2) (n=169) had Cys-C levels higher than the 95th percentile in controls (1.03  mg/l), consistent with a preclinical CKD, which was associated with hypertension and insulin resistance. Considering eGFRcr-cys, CKD (stages G3a, G3b, 4) was diagnosed in 13.7% of PHPT patients. Estimated GFRcr-cys, but not eGFR based on creatinine, was predicted by insulin resistance and hypertension and positively correlated with CVD.

CONCLUSIONS

Elevated Cys-C levels were associated with ionized calcium, cardiometabolic risk factors and CVD, and identified preclinical CKD in PHPT patients.

Is surgery necessary for 'mild' or 'asymptomatic' hyperparathyroidism?

A large majority of the currently diagnosed patients with hyperparathyroidism (PHPT) are mild or asymptomatic, mainly women after menopause. Following the debate held at the 16th European Congress of Endocrinology in Wroclaw (Poland) from May 3-7, 2014, arguments are here presented by a surgeon and a medical practitioner considering these situations rather have to profit from surgery, or simply from survey. For the trained endocrine surgeon, it is evident that parathyroidectomy confirms the diagnosis and undoubtedly reduces the discomfort felt by certain patients, prevents all risks of complications, removes patients and medical teams from the monitoring and represents a real individual financial benefit. On the other hand, the medical practitioner considers that mild or asymptomatic PHPT is commonly stable, and very rare are the subjects at risk of complications, particularly of fractures; prevention of vascular and metabolic disorders, nephrolithiasis and bone rarefaction justify regular physical exercise, a safe alimentation, a sufficient calcium and high water intake, the correction of the frequent deficit in vitamin D; finally has also to be considered the impossibility to refer to specialized (endocrine) surgeons, the enormous cohort of subjects more than 50 years with 'mild' or 'asymptomatic' PHPT. The surgeon and the medical practitioner agree to consider that in patients with 'mild' or 'asymptomatic' disease, there is no place for medical treatments, in particular calcimimetics and bisphophonates. Both agree that further studies are needed to clarify the long-term prognosis of operated and non-operated PHPT in term of fractures, cardiovascular risk and mortality. Individual and collective cost/benefit ratios of surgery or survey are also still imperfectly evaluated.

Parathyroid hormone, cognitive function and dementia: a systematic review

Background

Metabolic factors are increasingly recognized to play an important role in the pathogenesis of Alzheimer’s disease and dementia. Abnormal parathyroid hormone (PTH) levels play a role in neuronal calcium dysregulation, hypoperfusion and disrupted neuronal signaling. Some studies support a significant link between PTH levels and dementia whereas others do not.

Methods

We conducted a systematic review through January 2014 to evaluate the association between PTH and parathyroid conditions, cognitive function and dementia. Eleven electronic databases and citation indexes were searched including Medline, Embase and the Cochrane Library. Hand searches of selected journals, reference lists of primary studies and reviews were also conducted along with websites of key organizations. Two reviewers independently screened titles and abstracts of identified studies. Data extraction and study quality were performed by one and checked by a second reviewer using predefined criteria. A narrative synthesis was performed due to the heterogeneity of included studies.

Results

The twenty-seven studies identified were of low and moderate quality, and challenging to synthesize due to inadequate reporting. Findings from six observational studies were mixed but suggest a link between higher serum PTH levels and increased odds of poor cognition or dementia. Two case-control studies of hypoparathyroidism provide limited evidence for a link with poorer cognitive function. Thirteen pre-post surgery studies for primary hyperparathyroidism show mixed evidence for improvements in memory though limited agreement in other cognitive domains. There was some degree of cognitive impairment and improvement postoperatively in observational studies of secondary hyperparathyroidism but no evident pattern of associations with specific cognitive domains.

Conclusions

Mixed evidence offers weak support for a link between PTH, cognition and dementia due to the paucity of high quality research in this area.

Cardiovascular risk and metabolic syndrome in primary hyperparathyroidism and their correlation to different clinical forms

Cardiometabolic disorders have been associated with primary hyperparathyroidism (PHPT), while the relationship of cardiovascular risk score (CRS) and metabolic syndrome (MS) with different clinical presentation of PHPT remains undefined. Our aim was to evaluate CRS, MS and its components in PHPT looking for their correlation to different clinical forms. In 68 consecutive PHPT patients and 68 matched controls, CRS, MS and its components were assessed to perform an observational case-control study at an ambulatory referral center for Bone Metabolism Diseases. Patients were stratified in symptomatic and asymptomatic PHPT; these latter were divided in high-risk and low-risk subgroups for end-organ damage. An increased proportion of PHPT patients had intermediate-high CRS and MS (mean, 95 % Confidence Interval (CI) 51.5 %, 39.6-63.3 and 20.6 %, 11.0-30.2, respectively, p < 0.02 vs. controls). Intermediate-high CRS was prevalent both in symptomatic and low-risk asymptomatic PHPT while MS resulted prevalent in low-risk asymptomatic but not in symptomatic PHPT. Type 2 DM, IFG, mixed dyslipidemia, hypertriglyceridemia, HDL-hypocholesterolemia, and LDL-hypercholesterolemia predominated in low-risk asymptomatic, while only LDL-hypercholesterolemia prevailed also in symptomatic PHPT. In patients and controls without cardiometabolic risk factors, HOMA-IR index was significantly increased in PHPT vs. controls (p < 0.03) and associated to total calcium (R = 0.73; p < 0.001). By multivariate analysis low-risk asymptomatic PHPT predicted MS after adjusting for age, sex, and BMI. Our data show an increased frequency of intermediate-high CRS both in symptomatic and low-risk asymptomatic PHPT while MS prevails in low-risk asymptomatic PHPT, supporting the potential for cardiovascular morbidity and mortality also in this form.

Current issues in the presentation of asymptomatic primary hyperparathyroidism: proceedings of the Fourth International Workshop

OBJECTIVE

This report summarizes data on traditional and nontraditional manifestations of primary hyperparathyroidism (PHPT) that have been published since the last International Workshop on PHPT.

PARTICIPANTS

This subgroup was constituted by the Steering Committee to address key questions related to the presentation of PHPT. Consensus was established at a closed meeting of the Expert Panel that followed.

EVIDENCE

Data from the 5-year period between 2008 and 2013 were presented and discussed to determine whether they support changes in recommendations for surgery or nonsurgical follow-up.

CONSENSUS PROCESS

Questions were developed by the International Task Force on PHPT. A comprehensive literature search for relevant studies was undertaken. After extensive review and discussion, the subgroup came to agreement on what changes in the recommendations for surgery or nonsurgical follow-up of asymptomatic PHPT should be made to the Expert Panel.

CONCLUSIONS

1) There are limited new data available on the natural history of asymptomatic PHPT. Although recognition of normocalcemic PHPT (normal serum calcium with elevated PTH concentrations; no secondary cause for hyperparathyroidism) is increasing, data on the clinical presentation and natural history of this phenotype are limited. 2) Although there are geographic differences in the predominant phenotypes of PHPT (symptomatic, asymptomatic, normocalcemic), they do not justify geography-specific management guidelines. 3) Recent data using newer, higher resolution imaging and analytic methods have revealed that in asymptomatic PHPT, both trabecular bone and cortical bone are affected. 4) Clinically silent nephrolithiasis and nephrocalcinosis can be detected by renal imaging and should be listed as a new criterion for surgery. 5) Current data do not support a cardiovascular evaluation or surgery for the purpose of improving cardiovascular markers, anatomical or functional abnormalities. 6) Some patients with mild PHPT have neuropsychological complaints and cognitive abnormalities, and some of these patients may benefit from surgical intervention. However, it is not possible at this time to predict which patients with neuropsychological complaints or cognitive issues will improve after successful parathyroid surgery.

The value and role of low dose methylene blue in the surgical management of hyperparathyroidism

INTRODUCTION

Methylene blue (MB) has been used in the identification of abnormal parathyroid glands in surgery for hyperparathyroidism. Its efficacy and safety profile have been questioned recently and this study sought to demonstrate such aspects in a unit where its use is routine.

METHODS

Prospective data collected over six years in a single surgeon's practice were interrogated to identify factors affecting MB staining, side effects suffered and unusual cases where the dye was invaluable in locating the diseased gland.

RESULTS

A total of 98 patients underwent MB infusion. Of these, 77 cases (78.6%) stained positively with MB and 21 (21.4%) did not. Six patients suffered side effects but there were no cases of neurotoxicity. No positive predictive factors of dye uptake were found. MB was particularly useful in cases of intrathyroidal and ectopic glands as well as improving efficiency in both targeted and open parathyroidectomy.

CONCLUSIONS

This series shows that when used correctly, MB is efficacious in locating diseased parathyroid glands, with similar sensitivity rates to preoperative ultrasonography and radionucleotide imaging. Adverse effects were much lower than published previously, which may be attributed to the low dose of MB used (3.5 mg/kg).

Predictors of renal function in primary hyperparathyroidism

CONTEXT

Current guidelines for parathyroidectomy in primary hyperparathyroidism (PHPT) include an estimated glomerular filtration rate (eGFR) less than 60 mL/min per 1.73 m(2). Although the biochemical abnormalities associated with PHPT could impair renal function, there are currently no data examining whether more severe hypercalcemia, hypercalciuria, or nephrolithiasis are associated with chronic kidney disease (CKD) in mild PHPT.

OBJECTIVE

This cross-sectional study evaluated predictors of renal function in PHPT.

DESIGN

This is a case series of PHPT patients with (eGFR < 60 mL/min per 1.73 m(2)) and without (eGFR ≥ 60 mL/min per 1.73 m(2)) CKD.

SETTINGS AND PARTICIPANTS

We studied 114 PHPT patients in a university hospital setting.

OUTCOME MEASURES

We identified predictors of renal function using multiple linear regression.

RESULTS

eGFR was associated with age, hypertension, antihypertensive medication use, fasting glucose, and 25-hydroxyvitamin D. eGFR was positively rather than negatively associated with several PHPT disease severity indices including history of nephrolithiasis, 24-hour urinary calcium excretion, and 1,25-dihydroxyvitamin D but not serum calcium or PTH levels. An eGFR less than 60 mL/min per 1.73 m(2) was observed in 15% (n = 17), all of whom had stage 3 CKD (eGFR 30-59 mL/min per 1.73 m(2)). Those with CKD were older, had higher 25-hydroxyvitamin D levels and lower 1,25-dihydroxyvitamin D levels, and were more likely to be hypertensive than those without CKD. There were no between-group (<60 vs ≥60 mL/min per 1.73 m(2)) differences in serum calcium, PTH, nephrolithiasis, or meeting surgical criteria other than eGFR. Multiple linear regression indicated that age and diastolic blood pressure were negatively associated with eGFR, whereas serum calcium, kidney stones, and alcohol use were positive predictors. Calculation of eGFR using either the Modification of Diet in Renal Disease or Chronic Kidney Disease Epidemiology Collaboration equation yielded similar results.

CONCLUSIONS

PHPT patients with stage 3 CKD do not have biochemical or clinical evidence of more severe hyperparathyroidism compared with those without CKD. Traditional risk factors, rather than clinical or biochemical indices of PHPT, are associated with lower eGFR in mild PHPT.

Sestamibi scintigraphy for parathyroid localisation: a reminder of the dangers of false positives

Surgical parathyroidectomy is the only curative treatment for primary hyperparathyroidism. As minimally invasive parathyroidectomy increases in popularity, so does reliance on preoperative parathyroid localisation techniques. One such technique is sestamibi scintigraphy. We report a case of false-positive sestamibi scintigraphy caused by follicular variant of papillary thyroid carcinoma. Subsequent completion thyroidectomy was not possible due to widespread postoperative fibrosis. This case, therefore, highlights the potential dangers of false-positive results due to thyroid carcinoma and encourages surgeons to consider this possibility when faced with intrathyroidal or otherwise ambiguous parathyroid localisation results.

Mineralocorticoid receptor antagonism confers cardioprotection in heart failure

The symptoms and signs constituting the congestive heart failure (CHF) syndrome have their pathophysiologic origins rooted in a salt-avid renal state mediated by effector hormones of the renin-angiotensin-aldosterone and adrenergic nervous systems. Controlled clinical trials, conducted over the past decade in patients having minimally to markedly severe symptomatic heart failure, have demonstrated the efficacy of a pharmacologic regimen that interferes with these hormones, including aldosterone receptor binding with either spironolactone or eplerenone. Potential pathophysiologic mechanisms, which have not hitherto been considered involved for the salutary responses and cardioprotection provided by these mineralocorticoid receptor antagonists, are reviewed herein. In particular, we focus on the less well-recognized impact of catecholamines and aldosterone on monovalent and divalent cation dyshomeostasis, which leads to hypokalemia, hypomagnesemia, ionized hypocalcemia with secondary hyperparathyroidism and hypozincemia. Attendant adverse cardiac consequences include a delay in myocardial repolarization with increased propensity for supraventricular and ventricular arrhythmias, and compromised antioxidant defenses with increased susceptibility to nonischemic cardiomyocyte necrosis.

Primary hyperparathyroidism is associated with abnormal cortical and trabecular microstructure and reduced bone stiffness in postmenopausal women

Typically, in the milder form of primary hyperparathyroidism (PHPT), now seen in most countries, bone density by dual-energy X-ray absorptiometry (DXA) and detailed analyses of iliac crest bone biopsies by histomorphometry and micro-computed tomography (µCT) show detrimental effects in cortical bone, whereas the trabecular site (lumbar spine by DXA) and the trabecular compartment (by bone biopsy) appear to be relatively well preserved. Despite these findings, fracture risk at both vertebral and nonvertebral sites is increased in PHPT. Emerging technologies, such as high-resolution peripheral quantitative computed tomography (HRpQCT), may provide additional insight into microstructural features at sites such as the forearm and tibia that have heretofore not been easily accessible. Using HRpQCT, we determined cortical and trabecular microstructure at the radius and tibia in 51 postmenopausal women with PHPT and 120 controls. Individual trabecula segmentation (ITS) and micro-finite element (µFE) analyses of the HRpQCT images were also performed to further understand how the abnormalities seen by HRpQCT might translate into effects on bone strength. Women with PHPT showed, at both sites, decreased volumetric densities at trabecular and cortical compartments, thinner cortices, and more widely spaced and heterogeneously distributed trabeculae. At the radius, trabeculae were thinner and fewer in PHPT. The radius was affected to a greater extent in the trabecular compartment than the tibia. ITS analyses revealed, at both sites, that plate-like trabeculae were depleted, with a resultant reduction in the plate/rod ratio. Microarchitectural abnormalities were evident by decreased plate-rod and plate-plate junctions at the radius and tibia, and rod-rod junctions at the radius. These trabecular and cortical abnormalities resulted in decreased whole-bone stiffness and trabecular stiffness. These results provide evidence that in PHPT, microstructural abnormalities are pervasive and not limited to the cortical compartment, which may help to account for increased global fracture risk in PHPT.

Trabecular bone score (TBS)--a novel method to evaluate bone microarchitectural texture in patients with primary hyperparathyroidism

CONTEXT

In the milder form of primary hyperparathyroidism (PHPT), cancellous bone, represented by areal bone mineral density at the lumbar spine by dual-energy x-ray absorptiometry (DXA), is preserved. This finding is in contrast to high-resolution peripheral quantitative computed tomography (HRpQCT) results of abnormal trabecular microstructure and epidemiological evidence for increased overall fracture risk in PHPT. Because DXA does not directly measure trabecular bone and HRpQCT is not widely available, we used trabecular bone score (TBS), a novel gray-level textural analysis applied to spine DXA images, to estimate indirectly trabecular microarchitecture.

OBJECTIVE

The purpose of this study was to assess TBS from spine DXA images in relation to HRpQCT indices and bone stiffness in radius and tibia in PHPT.

DESIGN AND SETTING

This was a cross-sectional study conducted in a referral center.

PATIENTS

Participants were 22 postmenopausal women with PHPT.

MAIN OUTCOME MEASURES

Outcomes measured were areal bone mineral density by DXA, TBS indices derived from DXA images, HRpQCT standard measures, and bone stiffness assessed by finite element analysis at distal radius and tibia.

RESULTS

TBS in PHPT was low at 1.24, representing abnormal trabecular microstructure (normal ≥1.35). TBS was correlated with whole bone stiffness and all HRpQCT indices, except for trabecular thickness and trabecular stiffness at the radius. At the tibia, correlations were observed between TBS and volumetric densities, cortical thickness, trabecular bone volume, and whole bone stiffness. TBS correlated with all indices of trabecular microarchitecture, except trabecular thickness, after adjustment for body weight.

CONCLUSION

TBS, a measurement technology readily available by DXA, shows promise in the clinical assessment of trabecular microstructure in PHPT.

Cardiovascular diseases in older patients with osteoporotic hip fracture: prevalence, disturbances in mineral and bone metabolism, and bidirectional links

BACKGROUND

Considerable controversy exists regarding the contribution of mineral/bone metabolism abnormalities to the association between cardiovascular diseases (CVDs) and osteoporotic fractures.

AIMS AND METHODS

To determine the relationships between mineral/bone metabolism biomarkers and CVD in 746 older patients with hip fracture, clinical data were recorded and serum concentrations of parathyroid hormone (PTH), 25-hydroxyvitamin D, calcium, phosphate, magnesium, troponin I, parameters of bone turnover, and renal, liver, and thyroid functions were measured.

RESULTS

CVDs were diagnosed in 472 (63.3%) patients. Vitamin D deficiency was similarly prevalent in patients with (78.0%) and without (82.1%) CVD. The CVD group had significantly higher mean PTH concentrations (7.6 vs 6.0 pmol/L, P < 0.001), a higher prevalence of secondary hyperparathyroidism (SPTH) (PTH > 6.8 pmol/L, 43.0% vs 23.3%, P < 0.001), and excess bone resorption (urinary deoxypyridinoline corrected by creatinine [DPD/Cr] > 7.5 nmol/μmol, 87.9% vs 74.8%, P < 0.001). In multivariate regression analysis, SHPT (odds ratio [OR] 2.6, P = 0.007) and high DPD/Cr (OR 2.8, P = 0.016) were independent indictors of CVD. Compared to those with both PTH and DPD/Cr in the normal range, multivariate-adjusted ORs for the presence of CVD were 17.3 (P = 0.004) in subjects with SHPT and 9.7 (P < 0.001) in patients with high DPD/Cr. CVD was an independent predicator of SHPT (OR 2.8, P = 0.007) and excess DPD/Cr (OR 2.5, P = 0.031). CVD was predictive of postoperative myocardial injury, while SHPT was also an independent predictor of prolonged hospital stay and in-hospital death.

CONCLUSION

SHPT and excess bone resorption are independent pathophysiological mediators underlying the bidirectional associations between CVD and hip fracture, and therefore are important diagnostic and therapeutic targets.

Endothelial function in mild primary hyperparathyroidism

BACKGROUND

It is not known if endothelial dysfunction, an important early event in the pathogenesis of atherosclerosis, is present in mild primary hyperparathyroidism (PHPT) and if so, whether it improves following parathyroidectomy.

DESIGN

We measured flow-mediated vasodilation (FMD), which estimates endothelial function by ultrasound imaging, in patients prior to and 6 and 12 months after parathyroidectomy.

RESULTS

Forty-five patients with mild PHPT [80% female, 61 ± 1 (mean ± SE) years, serum calcium 2·65 ± 0·03 mm (10·6 ± 0·1 mg/dl), PTH 10·5 ± 0·7 pm (99 ± 7 pg/ml), 25-hydroxyvitamin D (25OHD) 70·3 ± 3·7 nm (28·2 ± 1·5 ng/ml)] were studied. Baseline FMD was normal (4·63 ± 0·51%; reference mean: 4·4 ± 0·1%) and was not associated with serum calcium, PTH or 25OHD levels. In the group as a whole, FMD did not change after surgery (6 months: 4·38 ± 0·83%, P = 0·72; 12 months: 5·07 ± 0·74%, P = 0·49). However, in those with abnormal baseline FMD (<2·2%; n = 15), FMD increased by 350%, normalizing by 6 months after surgery (baseline: 0·81± 0·19%; 6 months: 3·18 ± 0·79%, P = 0·02 vs baseline; 12months: 3·68 ± 1·22%, P = 0·04 vs baseline). Baseline calcium, PTH and 25OHD levels did not differ between those with abnormal vs normal FMD, nor did these indices predict postoperative change in FMD.

CONCLUSIONS

FMD is generally normal in patients with mild PHPT and is unchanged 1 year after parathyroidectomy. Although FMD may normalize after surgery in patients with baseline abnormalities, data do not support using endothelial dysfunction as an indicator for parathyroidectomy.

Nontraditional manifestations of primary hyperparathyroidism

Classical primary hyperparathyroidism (PHPT) was previously a multisystemic symptomatic disorder not only with overt skeletal and renal complications but also with neuropsychological, cardiovascular, gastrointestinal, and rheumatic effects. The presentation of PHPT has evolved, and today most patients are asymptomatic. Osteitis fibrosa cystica is rarely seen today, and nephrolithiasis is less common. Gastrointestinal and rheumatic symptoms are not part of the clinical spectrum of modern PHPT. It remains unclear whether neuropsychological symptoms and cardiovascular disease, neither of which are currently indications for recommending parathyroidectomy (PTX), are part of the modern phenotype of PHPT. A number of observational studies suggest that mild PHPT is associated with depression, decreased quality of life, and changes in cognition, but limited data from randomized controlled trials (RCTs) have not indicated consistent benefits after surgery. The increased cardiovascular morbidity and mortality in severe PHPT has not been definitively demonstrated in mild disease, although there is some evidence for more subtle cardiovascular abnormalities, such as increased vascular stiffness, among others. Results from observational studies that have assessed the effect of PTX on cardiovascular health have been conflicting. The single RCT in this area did not demonstrate that PTX was beneficial. Despite recent progress in these areas, more data from rigorously designed studies are needed to better inform the clinical management of patients with asymptomatic PHPT.

Results from a national survey on the management of primary hyperparathyroidism

BACKGROUND

Management of primary hyperparathyroidism (PHPT) continues to be challenging. At the Third International Workshop on PHPT, recent data on this disease were reviewed and new clinical recommendations were developed. There are few data on the influence of new guidelines in clinical practice.

AIM

We designed an online survey that was sent to all Spanish hospital endocrinology services.

METHODS

The questionnaire included 28 questions about diagnosis and management of PHPT. Ninety-nine of 131 sites (76%), giving health coverage to 70% of Spanish population, completed the survey.

RESULTS

The reported incidence of PHPT was 9.95/100,000 person-years. Heighty percent of patients were asymptomatic. Each center performed a median (Q1, Q3) of 12 (6, 20) parathyroidectomies/year. The median (Q1, Q3) percentage of curative interventions (at first trial) was 90% (80, 95). The main reasons for not performing surgery were, by decreasing frequency: surgery contraindication, patient's refusal, loss of monitoring, limited surgery experience. Localization techniques were used in 83% of cases. The main criteria for parathyroidectomy in asymptomatic patients were Ca≥2.875 mmol/l (79%), Tscore ≤-2.5 SD at any site (91%), age <50 yr (80%) and glomerular filtration rate <60 ml/min/1.73 m 2 (82%). Minimally invasive surgery was performed in 42% of centers. Frequency of biochemistry and bone density determinations for non-surgically managed patients was in accordance with international guidelines.

CONCLUSIONS

The clinical practice of Spanish endocrinologists is consistent with the recommendations of the guidelines from the Third International Workshop for the management of PHPT.

Disturbances in calcium metabolism and cardiomyocyte necrosis: the role of calcitropic hormones

A synchronized dyshomeostasis of extra- and intracellular Ca(2+), expressed as plasma ionized hypocalcemia and excessive intracellular Ca(2+) accumulation, respectively, represents a common pathophysiologic scenario that accompanies several diverse disorders. These include low-renin and salt-sensitive hypertension, primary aldosteronism and hyperparathyroidism, congestive heart failure, acute and chronic hyperadrenergic stressor states, high dietary Na(+), and low dietary Ca(2+) with hypovitaminosis D. Homeostatic responses are invoked to restore normal extracellular [Ca(2+)](o), including increased plasma levels of parathyroid hormone and 1,25(OH)(2)D(3). However, in cardiomyocytes these calcitropic hormones concurrently promote cytosolic free [Ca(2+)](i) and mitochondrial [Ca(2+)](m) overloading. The latter sets into motion organellar-based oxidative stress, in which the rate of reactive oxygen species generation overwhelms their detoxification by endogenous antioxidant defenses, including those related to intrinsically coupled increments in intracellular Zn(2+). In turn, the opening potential of the mitochondrial permeability transition pore increases, allowing for osmotic swelling and ensuing organellar degeneration. Collectively, these pathophysiologic events represent the major components to a mitochondriocentric signal-transducer-effector pathway to cardiomyocyte necrosis. From necrotic cells, there follows a spillage of intracellular contents, including troponins, and a subsequent wound healing response with reparative fibrosis or scarring. Taken together, the loss of terminally differentiated cardiomyocytes from this postmitotic organ and the ensuing replacement fibrosis each contribute to the adverse structural remodeling of myocardium and progressive nature of heart failure. In conclusion, hormone-induced ionized hypocalcemia and intracellular Ca(2+) overloading comprise a pathophysiologic cascade common to diverse disorders and that initiates a mitochondriocentric pathway to nonischemic cardiomyocyte necrosis.

Arterial calcification and bone physiology: role of the bone-vascular axis

Bone never forms without vascular interactions. This simple statement of fact does not adequately reflect the physiological and pharmacological implications of the relationship. The vasculature is the conduit for nutrient exchange between bone and the rest of the body. The vasculature provides the sustentacular niche for development of osteoblast progenitors and is the conduit for egress of bone marrow cell products arising, in turn, from the osteoblast-dependent haematopoietic niche. Importantly, the second most calcified structure in humans after the skeleton is the vasculature. Once considered a passive process of dead and dying cells, vascular calcification has emerged as an actively regulated form of tissue biomineralization. Skeletal morphogens and osteochondrogenic transcription factors are expressed by cells within the vessel wall, which regulates the deposition of vascular calcium. Osteotropic hormones, including parathyroid hormone, regulate both vascular and skeletal mineralization. Cellular, endocrine and metabolic signals that flow bidirectionally between the vasculature and bone are necessary for both bone health and vascular health. Dysmetabolic states including diabetes mellitus, uraemia and hyperlipidaemia perturb the bone-vascular axis, giving rise to devastating vascular and skeletal disease. A detailed understanding of bone-vascular interactions is necessary to address the unmet clinical needs of an increasingly aged and dysmetabolic population.

Arterial structure and function in mild primary hyperparathyroidism is not directly related to parathyroid hormone, calcium, or vitamin D

Objective

Elevated levels of calcium and parathyroid hormone (PTH), characteristics of primary hyperparathyroidism (PHPT), may be associated with cardiovascular morbidity and mortality in the general population. We evaluated the possible vascular effects of these risk factors in patients with mild PHPT by using standard methods and new imaging techniques.

Design

A prospective case-control study.

Subjects and Methods

Forty-eight patients with mild PHPT without any known cardiovascular risk factors were studied at baseline and at one year after parathyroidectomy (PTX) in comparison with 48 healthy age- and gender-matched controls. We measured biochemical variables, augmentation index (AIx), aortic pulse wave velocity (PWV_ao), radial (IMT_rad) and common carotid artery (IMT_cca) intima media thicknesses, and the grayscale median (IM-GSM) of the latter.

Results

No significant differences were observed between PHPT patients and controls at baseline for AIx (28.6±12.2 vs. 27.7±12.8%), IMT_rad (0.271±0.060 vs. 0.255±0.053 mm), IMT_cca (0.688±0.113 vs. 0.680±0.135 mm), or IM-GSM (82.3±17.2 vs. 86.5±15.3), while PWV_ao was slightly higher in patients (8.68±1.50 vs. 8.13±1.55, p<0.05). Systolic blood pressure (SBP), calcium, and PTH were higher in patients compared with controls, and decreased after PTX, while vitamin D was lower in patients and increased after PTX. While AIx, PWV_ao, IMT_rad, and IMT_cca were related to SBP, neither correlated to vitamin D levels. Only PWV_ao correlated weakly to plasma PTH (r = 0.29, p<0.01) and ionized calcium (r = 0.22, p<0.05) but showed no relation when age and SBP were adjusted for.

Conclusion

We found normal arterial function despite high calcium, PTH, and low vitamin D levels, in patients with mild PHPT without cardiovascular risk factors. The cardiovascular risk associated with low vitamin D and/or high PTH and calcium levels may be explained by their coupling to blood pressure and other risk factors rather than direct effects on arterial structure.

Cardiorenal syndrome and vitamin D receptor activation in chronic kidney disease

Cardiorenal syndrome (CRS) refers to a constellation of conditions whereby heart and kidney diseases are pathophysiologically connected. For clinical purposes, it would be more appropriate to emphasize the pathophysiological pathways to classify CRS into: (1) hemodynamic, (2) atherosclerotic, (3) uremic, (4) neurohumoral, (5) anemic–hematologic, (6) inflammatory–oxidative, (7) vitamin D receptor (VDR) and/or FGF23-, and (8) multifactorial CRS. In recent years, there have been a preponderance data indicating that vitamin D and VDR play an important role in the combination of renal and cardiac diseases. This review focuses on some important findings about VDR activation and its role in CRS, which exists frequently in chronic kidney disease patients and is a main cause of morbidity and mortality. Pathophysiological pathways related to suboptimal or defective VDR activation may play a role in causing or aggravating CRS. VDR activation using newer agents including vitamin D mimetics (such as paricalcitol and maxacalcitol) are promising agents, which may be related to their selectivity in activating VDR by means of attracting different post-D-complex cofactors. Some, but not all, studies have confirmed the survival advantages of D-mimetics as compared to non-selective VDR activators. Higher doses of D-mimetic per unit of parathyroid hormone (paricalcitol to parathyroid hormone ratio) is associated with greater survival, and the survival advantages of African American dialysis patients could be explained by higher doses of paricalcitol (>10 μg/week). More studies are needed to verify these data and to explore additional avenues for CRS management via modulating VDR pathway.

Catabolic and anabolic actions of parathyroid hormone on the skeleton

PTH, an 84-amino acid peptide hormone synthesized by the parathyroid glands, is essential for the maintenance of calcium homeostasis.While in its traditional metabolic role, PTH helps to maintain the serum calcium concentration within narrow, normal limits and participates as a determinant of bone remodeling, more specific actions, described as catabolic and anabolic are also well known. Clinically, the catabolic effect of PTH is best represented by primary hyperparathyroidism (PHPT), while the osteoanabolic effect of PTH is best seen when PTH or its biological amino-terminal fragment [PTH(1-34)] is used as a therapy for osteoporosis. These dual functions of PTH are unmasked under very specific pathological (PHPT) or therapeutic conditions. At the cellular level, PTH favors bone resorption, mostly by affecting the receptor activator of nuclear factor κ-B (RANK) ligand (RANKL)-osteoprotegerin- RANK system, leading to an increase in osteoclast formation and activity. Increased bone formation due to PTH therapy is explained best by its ability to enhance osteoblastogenesis and/or osteoblast survival. The PTH-induced bone formation is mediated, in part, by a decrease in SOST/sclerostin expression in osteocytes. This review focuses on the dual anabolic and catabolic actions of PTH on bone, situations where one is enhanced over the other, and the cellular and molecular mechanisms by which these actions are mediated.

Primary hyperparathyroidism influences the expression of inflammatory and metabolic genes in adipose tissue

Background

Primary hyperparathyroidism (PHPT) is characterised by increased production of parathyroid hormone (PTH) resulting in elevated serum calcium levels. The influence on bone metabolism with altered bone resorption is the most studied clinical condition in PHPT. In addition to this, patients with PHPT are at increased risk of non-skeletal diseases, such as impaired insulin sensitivity, arterial hypertension and increased risk of death by cardiovascular diseases (CVD), possibly mediated by a chronic low-grade inflammation. The aim of this study was to investigate whether adipose tissue reflects the low-grade inflammation observed in PHPT patients.

Methodology/Principal Findings

Subcutaneous fat tissue from the neck was sampled from 16 non-obese patients with PHPT and from 16 patients operated for benign thyroid diseases, serving as weight-matched controls. RNA was extracted and global gene expression was analysed with Illumina BeadArray Technology. We found 608 differentially expressed genes (q-value<0.05), of which 347 were up-regulated and 261 were down-regulated. Gene ontology analysis showed that PHPT patients expressed increased levels of genes involved in immunity and defense (e.g. matrix metallopeptidase 9, S100 calcium binding protein A8 and A9, CD14, folate receptor 2), and reduced levels of genes involved in metabolic processes. Analysis of transcription factor binding sites present in the differentially expressed genes corroborated the up-regulation of inflammatory processes.

Conclusions/Significance

Our findings demonstrate that PHPT strongly influences gene regulation in fat tissue, which may result in altered adipose tissue function and release of pathogenic factors that increase the risk of CVD.

Cinacalcet as alternative treatment for primary hyperparathyroidism: achievements and prospects

Primary hyperparathyroidism (pHPT), which most frequently occurs asymptomatically, is a common endocrine disease associated with increased morbidity and mortality. The newly introduced management guidelines as well as the recent availability of the first calcimimetic offer a highly promising therapeutic option for patients with pHPT. Cinacalcet, the first available calcimimetic, increases the sensitivity of the calcium-sensing receptor (CaR) to circulating serum calcium, thereby safely reducing serum calcium and PTH concentrations in patients with mild-to-moderate pHPT, intractable disease, and also parathyroid carcinoma. Cinacalcet has proved efficient in short- and long-term controls of hypercalcemia and, though bone mineral density was not improved, the available data point to cinacalcet as the treatment of choice in non-operable patients with pHPT. These results encompass a wide spectrum of disease severity. Results are pending as to whether cinacalcet decreases mortality and morbidity in pHPT, confirmation of which would conclusively recommend this drug as a valid alternative to surgery.