Impairment of flow mediated vasodilatation of brachial artery in patients with primary hyperparathyroidism

Endothelial dysfunction and cardiovascular diseases: The role of human induced pluripotent stem cells and tissue engineering

Cardiovascular disease (CVD) remains to be the leading cause of death globally today and therefore the need for the development of novel therapies has become increasingly important in the cardiovascular field. The mechanism(s) behind the pathophysiology of CVD have been laboriously investigated in both stem cell and bioengineering laboratories. Scientific breakthroughs have paved the way to better mimic cell types of interest in recent years, with the ability to generate any cell type from reprogrammed human pluripotent stem cells. Mimicking the native extracellular matrix using both organic and inorganic biomaterials has allowed full organs to be recapitulated in vitro. In this paper, we will review techniques from both stem cell biology and bioengineering which have been fruitfully combined and have fueled advances in the cardiovascular disease field. We will provide a brief introduction to CVD, reviewing some of the recent studies as related to the role of endothelial cells and endothelial cell dysfunction. Recent advances and the techniques widely used in both bioengineering and stem cell biology will be discussed, providing a broad overview of the collaboration between these two fields and their overall impact on tissue engineering in the cardiovascular devices and implications for treatment of cardiovascular disease.

Nontraditional Aspects of Sporadic Primary Hyperparathyroidism

Nontraditional aspects of primary hyperparathyroidism refer to the condition's rheumatic, gastrointestinal, cardiovascular, and neuropsychological effects. Although gastrointestinal and rheumatic symptomatology were features of classical primary hyperparathyroidism, they do not seem to be a part of the modern presentation of primary hyperparathyroidism. In contrast, neuropsychological symptoms such as altered mood and cognition, as well as cardiovascular disease, have been associated with the form of primary hyperparathyroidism seen today, but the relationship is not clearly causal. Evidence does not support reversibility after parathyroidectomy and therefore none of the nontraditional manifestations are considered sole indications for recommending surgery at this time.

Cardiovascular Risk in Patients with Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is one of the most common endocrine disorders characterized by parathyroid hormone (PTH)-dependent hypercalcemia. Cardinal features include low trauma fractures, nephrolithiasis, and chronic kidney disease. Several experimental studies established that parathyroid hormone exerts actions on the cardiovascular (CV) system, including vasodilatation and positive inotropic and chronotropic effects. Observational studies, especially in severe cases, report a higher prevalence of hypertension, diabetes mellitus, lipid abnormalities, endothelial dysfunction, arrhythmias, and left ventricular hypertrophy in patients with PHPT, while the risk of CV events seems to be increased in severe cases. However, the effect of surgery is inconsistent on CV abnormalities and, more importantly, on CV disease (CVD) events, especially in mild cases. In the current review, we describe the available evidence linking PHPT and CVD, as well as the effect of surgical management and pharmacological treatment on CVD manifestations in patients with PHPT. Based on the current evidence, CVD is not considered an indication for surgery.

Non classical complications of primary hyperparathyroidism

Several studies suggested that the condition of primary hyperparathyroidism (PHPT) may be associated not only with the classical bone, kidney and gastrointestinal consequences, but also with cardiovascular, neuromuscular and articular complications, impaired quality of life and increased cancer risk. However, the only cardiovascular complications associated with PHPT, which seems to improve after parathyroidectomy, is left ventricular hypertrophy, while, data regarding the reversibility of hypertension, valve calcifications and increased vascular stiffness are inconsistent. Parathyroidectomy seems to ameliorate neuropsychological, cognitive disturbances and quality of life in moderate-severe PHPT, while data in mild PHPT are less clear. At variance, the effect of parathyroidectomy on neuromuscular and articular complications is still unknown, and no studies demonstrated a reduction of cancer risk after recovery from PHPT. Overall, to date, cardiovascular and neuropsychological evaluation are not recommended solely because of PHPT, nor cardiovascular disease, muscle weakness, and neuropsychological complications are indication for parathyroidectomy.

Cardiovascular manifestations of primary hyperparathyroidism: a narrative review

Data on cardiovascular disease in primary hyperparathyroidism (PHPT) are controversial; indeed, at present, cardiovascular involvement is not included among the criteria needed for parathyroidectomy. Aim of this narrative review is to analyze the available literature in an effort to better characterize cardiovascular involvement in PHPT. Due to physiological effects of both parathyroid hormone (PTH) and calcium on cardiomyocyte, cardiac conduction system, smooth vascular, endothelial and pancreatic beta cells, a number of data have been published regarding associations between symptomatic and mild PHPT with hypertension, arrhythmias, endothelial dysfunction (an early marker of atherosclerosis), glucose metabolism impairment and metabolic syndrome. However, the results, mainly derived from observational studies, are inconsistent. Furthermore, parathyroidectomy resulted in conflicting outcomes, which may be linked to several potential biases. In particular, differences in the methods utilized for excluding confounding co-existing cardiovascular risk factors together with differences in patient characteristics, with varying degrees of hypercalcemia, may have contributed to these discrepancies. The only meta-analysis carried out in PHPT patients, revealed a positive effect of parathyroidectomy on left ventricular mass index (a predictor of cardiovascular mortality) and more importantly, that the highest pre-operative PTH levels were associated with the greatest improvements. In normocalcemic PHPT, it has been demonstrated that cardiovascular risk factors are almost similar compared to hypercalcemic PHPT, thus strengthening the role of PTH in the cardiovascular involvement. Long-term longitudinal randomized trials are needed to determine the impact of parathyroidectomy on cardiovascular diseases and mortality in PHPT.

Is primary hyperparathyroidism a cause of endothelial dysfunction?

OBJECTIVE

Symptomatic primary hyperparathyroidism (PHPT) is thought to be related to increased cardiovascular morbidity and mortality. In our study, we aimed to investigate endothelial dysfunction and markers of subclinical atherosclerosis in patients with PHPT. Also we aimed to demonstrate the effect of vitamin D supplementation on these parameters.

MATERIALS AND METHODS

Twenty-nine patients followed by medical treatment (A), 25 preoperative (B) and 23 postoperative patients with PHPT (C), and 26 normocalcaemic subjects (D) were included. Groups were assessed by measurements of flow-mediated dilation (FMD), carotid intima-media thickness (CIMT), serum levels of sCD40L, high-sensitivity CRP (hs-CRP) and interleukin-8 (IL-8). Thirteen patients with low levels of 25-hydroxy-vitamin D (25OHD) in the medical treatment group were assessed before and 3 months after vitamin D replacement.

RESULTS

The median FMD was 5% in group A, 5.1% in group B, 7.6% in group C and 7.7% in group D. The FMD measurement in group A was significantly lower than groups C and D (P=.02) and was similar to the FMD measurement in group B. FMD measurements of group B were not significantly lower than groups C and D. In 13 patients with low 25OHD in group A, the median FMD increased to 7.07% from 4.71% after vitamin D replacement (P=.02).

CONCLUSION

Flow-mediated dilation was impaired in patients with PHPT, particularly in the medically observed group. Vitamin D supplementation seems to provide improvements in FMD in medically observed PHPT patients with low 25OHD levels, and this was the novel observation of our study.

Age and Gender Differences in the Association between Serum 25-Hydroxyvitamin D and Stroke in the General US Population: The National Health and Nutrition Examination Survey, 2001-2006

BACKGROUND

Previous findings on the association between serum 25(OH)D level and stroke have been controversial. We aimed to examine whether these controversial findings could be possibly due to difference in study participant characteristics, especially age and gender differences in these studies, by analyzing the data from a representative sample of the general US population.

METHODS

Data of 13,642 adults 20 years or older who participated in the 2001-2006 National Health and Nutrition Examination Survey were analyzed in this study. Serum 25(OH)D was used to reflect vitamin D status. Stroke history was self-reported using questionnaires. Unadjusted and adjusted logistic regression models were fitted using SAS survey procedures to investigate the associations between 25(OH)D level and stroke for the pooled sample and age-gender subgroups (men versus women, <50 years old versus ≥50 years old), respectively.

RESULTS

After adjusting for demographic and lifestyle covariates, vitamin D deficiency (defined as serum 25(OH)D < 12 ng/mL) was significantly associated with increased risk of stroke (adjusted odds ratio [OR] = 1.62, 95% confidence interval [CI] = 1.11, 2.36), and higher vitamin D levels were significantly associated with reduced risk of stroke (adjusted OR = .70, 95% CI = .51, .96). The association between high levels of serum 25(OH)D and stroke was particularly evident among young females (age ≤20 years to <50 years) (adjusted OR = .26, 95% CI = .14, .49).

CONCLUSIONS

The findings add to the evidence suggesting maintaining ideal 25(OH)D levels may reduce the risk of stroke among US adults, particularly in adult women younger than 50 years.

Excessive dietary phosphorus intake impairs endothelial function in young healthy men: a time- and dose-dependent study

Excessive dietary phosphorus (P) has been speculated to be a risk factor for cardiovascular disease (CVD). Here, we performed a double-blinded crossover study to investigate the time- and dose-dependent effects of dietary P intake on endothelial function in healthy subjects. Sixteen healthy male volunteers were given meals containing 400, 800, and 1,200 mg P (P400, P800, and P1200 meals, respectively) with at least 7 days between doses. There were no differences in nutritional composition among the experimental diets except for P content. Blood biochemistry data and flow-mediated dilation (%FMD) of the brachial artery were measured while fasted, at 0 h, 1 h, 2 h, and 4 h after meal ingestion, and the next morning while fasted. The P800 and P1200 meals significantly increased serum P levels at 1-4 h after ingestion. A significant decrease in %FMD was observed between 1-4 h,while the P400 meal did not affect %FMD. We observed no differences among meals in serum P levels or %FMD the next morning. A significant negative correlation was observed between %FMD and serum P. These results indicate that excessive dietary P intake can acutely impair endothelial function in healthy people.

Effect of teriparatide treatment on endothelial function, glucose metabolism and inflammation markers in patients with postmenopausal osteoporosis

OBJECTIVE

Teriparatide, an anabolic agent used in the treatment of postmenopausal osteoporosis, can induce effects similar to primary hyperparathyroidism. Our objective was to evaluate the effects of teriparatide on endothelial functions, glucose metabolism and inflammation markers in patients diagnosed with postmenopausal osteoporosis.

DESIGN, PATIENTS AND MEASUREMENTS

This was a single-centre, single-arm, 6-month prospective study. Twenty-three postmenopausal women over 65 years old with a lumbar spine or femoral neck T-score of -4·0 or lower and having at least two compression fractures in thoracic or lumbar spine were studied. Low-dose intermittent teriparatide (20 μg/day) was supplemented with calcium carbonate (1000 mg elemental calcium) and 880 IU cholecalciferol for 6 months. The biochemical parameters for glucose metabolism, inflammation and atherosclerosis were determined. For the assessment of vascular endothelial function, carotid intima-media thickness (CIMT), brachial artery intima-media thickness (BIMT), per cent change in flow-mediated dilation (FMD%) and nitroglycerine-induced dilations (NID%) were measured on ultrasonography.

RESULTS

The fasting plasma glucose, homoeostatic model assessment of insulin resistance, fibrinogen, homocysteine and high-density lipoprotein cholesterol increased significantly with teriparatide treatment (P < 0·05 for all). Baseline CIMT and BIMT did not change significantly with 6 months of teriparatide treatment (P > 0·05); however, FMD% and NID% showed significant decrease after treatment (P < 0·01 for both).

CONCLUSIONS

Intermittent teriparatide treatment may adversely affect some parameters of glucose metabolism, inflammation and endothelial function. On the basis of our findings, further large-scale and controlled studies are needed to clarify the exact effect of teriparatide treatment on glucose metabolism, inflammation and endothelial function.

Impaired endothelial function in patients with mild primary hyperparathyroidism improves after parathyroidectomy

BACKGROUND

Primary hyperparathyroidism (PHPT) is associated with cardiovascular morbidity; however, data on the reversibility of cardiovascular disease in mild primary hyperparathyroidism are conflicting. The aim of this study was to assess endothelial function in patients with mild PHPT before and after parathyroidectomy (Ptx).

METHODS

We prospectively evaluated 53 patients with mild PHPT (Group 1; 45 women, eight men; aged 52 ± 3·1 years) and 46 healthy control subjects (Group 2; 38 women, eight men; aged 46 ± 9·5 years). Endothelial function was measured as flow-mediated dilation (FMD) and carotid intima-media thickness (CIMT) using Doppler ultrasonography. Patients with diabetes mellitus, coronary heart disease, impaired renal function, hyperthyroidism, hypothyroidism and a history of smoking were excluded from the study. Patients were studied at baseline and 6-12 months after the first evaluation.

RESULTS

There were no differences with respect to age, gender and BMI between the two groups. Hypertension prevalence was three times higher in group 1 than in controls. % FMD was lower in group 1 than in group 2 (2·6 ± 1·2 vs 14·8 ± 9·6, P < 0·001). CIMT was higher in patients with PHPT than controls (0·69 ± 0·18 vs 0·61 ± 0·12, P = 0·045). This significance remained when hypertensive patients were excluded from the analysis. While FMD and CIMT improved significantly after Ptx, there were no differences in mild PHPT patients who followed without parathyroidectomy.

CONCLUSION

FMD and CIMT are impaired in patients with mild PHPT compared to controls and improved significantly after a successful Ptx. Ptx improves endothelial function in patients with mild PHPT that may lead to decreased cardiovascular morbidity and mortality.

Fluctuating plasma phosphorus level by changes in dietary phosphorus intake induces endothelial dysfunction

High serum phosphorus (P) impairs endothelial function by increasing oxidative stress and decreasing nitric oxide production. Serum P levels fluctuate due to circadian rhythms or dietary P intake in healthy people and due to dialysis in end-stage chronic kidney disease patients. Here we examined whether fluctuating plasma P caused by changes in dietary P intake may be involved in endothelial dysfunction, resulting in increased cardiovascular risk. Rats were fed a diet containing 0.6% P for 16 days (control group), or a diet alternating between 0.02% P and 1.2% P (LH group) or between 1.2% P and 0.02% P (HL group) every 2 days; the total amount of P intake among the groups during the feeding period was similar. In the LH and HL groups, endothelial-dependent vasodilation significantly decreased plasma 8-(OH)dG level significantly increased, and the expression of inflammatory factors such as MCP-1 increased in the endothelium as compared with the control group. These data indicate that repetitive fluctuations of plasma P caused by varying dietary P intake can impair endothelial function via increased oxidative stress and inflammatory response. Taken together, these results suggest that habitual fluctuation of dietary P intake might be a cause of cardiovascular disease through endothelial dysfunction, especially in chronic kidney disease patients.

Effects of switching from efavirenz to raltegravir on endothelial function, bone mineral metabolism, inflammation, and renal function: a randomized, controlled trial

We performed a randomized controlled trial in 30 HIV-infected participants to either continue tenofovir/emtricitabine/efavirenz (Continuation Group) or switch to tenofovir/emtricitabine/raltegravir (Switch Group) for 24 weeks. There were no significant differences in the changes in flow-mediated dilation, 25(OH) vitamin D, or parathyroid hormone levels. Total cholesterol, high sensitivity C-reactive protein, serum alkaline phosphatase, sCD14 levels, and renal function significantly declined in the Switch Group compared with the Continuation Group; however, sCD163 levels significantly increased in the Switch Group. These findings suggest that raltegravir is not inherently more beneficial to endothelial function compared with efavirenz but may impact renal function and monocyte activation.

Parathyroid hormone and arterial dysfunction in the multi-ethnic study of atherosclerosis

OBJECTIVE

High circulating concentrations of parathyroid hormone (PTH) have been associated with increased risks of hypertension, left ventricular hypertrophy, congestive heart failure and cardiovascular mortality. Impaired arterial function is a potential mechanism for these associations. We tested whether serum PTH concentration is associated with measures of arterial function.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 6545 persons without clinical cardiovascular disease participating in the community-based Multi-Ethnic Study of Atherosclerosis.

MEASUREMENTS

Brachial artery flow-mediated dilation (FMD) as well as aortic pulse pressure and arterial pulse parameters derived from Windkessel modelling of the radial pressure waveform.

RESULTS

Higher serum PTH concentration was associated with lower brachial artery FMD (mean difference -0·09% per 10 pg/ml PTH), higher aortic pulse pressure (0·53 mmHg per 10 pg/ml) and reduced Windkessel capacitive index C1 (large artery elasticity, -0·12 ml/mmHg × 10 per 10 pg/ml), adjusting for potential confounding variables (all P-values ≤ 0·001). These relationships were independent of serum calcium concentration, serum 25-hydroxyvitamin D concentration and estimated glomerular filtration rate and were consistent across relevant participant subgroups. Associations of PTH with aortic pulse pressure and capacitive index C1 were attenuated after adjustment for blood pressure. Serum PTH concentration was not associated with the oscillatory index C2 (small artery elasticity).

CONCLUSIONS

Higher serum PTH concentration was associated with impaired endothelial function, increased aortic pulse pressure and decreased capacitive index C1 in a large, diverse, community-based population. These relationships may help explain previously observed associations of elevated PTH with cardiovascular disease.

Article Commentary: Nonclassical Symptoms of Primary Hyperparathyroidism and Their Response to Parathyroidectomy

An estimated 100,000 new patients are diagnosed with primary hyperparathyroidism (PHPT) each year in the United States.1 In the past, patients with PHPT typically presented with “stones, bones, abdominal groans, and psychic moans” but today patients often present with more subtle symptoms and physiologic changes associated with earlier stages of disease. Patients without the classic symptoms of PHPT are often referred to as “asymptomatic.” These patients frequently pose a conundrum for clinicians. Uncertainties remain as to which symptoms truly represent PHPT and which are related to comorbidities or the aging process. To address these uncertainties, we review most recent literature regarding the nonclassical manifestations of PHPT and their response to parathyroidectomy.

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.

Relationship among endothelial response to hyperemia, bone marrow-derived progenitor cells, and parathyroid hormone in renal transplantation

BACKGROUND

Endothelial dysfunction may contribute to modulate cardiovascular complications in renal transplant recipients (RTRs), and a relationship between endothelial dysfunction and parathyroid hormone (PTH) levels in RTRs has been demonstrated. We evaluated the relationship between endothelial response to hyperemia and circulating progenitor cells (CPCs) and endothelial progenitor cells (EPCs) PTH, and genetic parameters in RTRs.

METHODS

In 120 RTRs and in healthy subjects without (n=107, group A) and with cardiovascular risk factors (n=109, group B), we evaluated endothelial response to hyperemia through digital tonometry (peripheral arterial tonometry) detected by reactive hyperemia index (RHI) and EPCs and CPCs by flow cytometry.

RESULTS

In RTRs, RHI median value was lower than in group A (P=0.05). EPC number was significantly lower in RTRs than in groups A and B (P<0.0001), whereas PTH median value was significantly higher (P<0.0001). In RTRs, RHI values were significantly lower according to the presence of three or more risk factors (P=0.04) and positively correlated with EPCs (P=0.04) but not with PTH (P=0.2). In patients who underwent dialysis for more than 5 years, lower RHI values (P=0.08), EPC number (P=0.5), and higher PTH concentrations (P=0.09) than in patients with less than 1 year dialysis time were observed. No relationship between eNOS gene -786T>C, 894G>T, and 4a/4b polymorphisms and RHI, EPC, and CPC number was found.

CONCLUSIONS

This study shows an altered endothelial response, associated with reduced EPCs, and increased PTH in RTRs; the evaluation of endothelial status in RTRs may contribute to better assess the risk profile of these patients.

The assessment of left ventricular systolic asynchrony in patients with primary hyperparathyroidism

OBJECTIVES

Primary hyperparathyroidism (PHP) is associated with a variety of cardiovascular disturbances such as left ventricular (LV) hypertrophy, diastolic cardiac dysfunction, and hypertension. LV asynchrony is defined as the loss of the simultaneous peak contraction of corresponding cardiac segments. The objective of this study was to assess systolic asynchrony in patients with overt hyperparthyroidism.

METHODS

Asynchrony was evaluated in 22 patients with PHP and 24 controls. All the patients and controls were subjected to a tissue synchronization imaging (TSI). The time to regional peak systolic tissue velocity (Ts) in LV by the six-basal-six-midsegmental model was measured on ejection phase TSI images and four TSI parameters of systolic asynchrony were computed.

RESULTS

All TSI parameters of LV asynchrony increased in patients with PHP patients compared to the controls: the standard deviation (SD) of the 12 LV segments Ts (37.3±20.6 vs. 21.5±11.1, P=0.01); the maximal difference in Ts between any 2 of the 12 LV segments (111.2±59.8 vs. 70.2±32.1, P=0.01); the SD of the 6 basal LV segments (42.9±36.4 vs. 18.5±13, P=0.003); and the maximal difference in Ts between any 2 of the 6 basal LV segments (89.6±50.5 vs. 48±31.1, P=0.003).

CONCLUSION

Patients with PHP show an evidence of LV asynchrony by TSI. Asynchrony may contribute to the harmful cardiovascular effects of PHP.

Cardiovascular effects of calcium supplementation

Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27-31% increase in risk of myocardial infarction and a 12-20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and show consistent risk across the trials. The fact that cardiovascular events were not primary endpoints of any of these studies will introduce noise but not bias into the data. A recent re-analysis of the Women's Health Initiative suggests that co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, on the function of vascular cells, and on blood coagulation. Calcium-sensing receptors might mediate some of these effects. Because calcium supplements produce small reductions in fracture risk and a small increase in cardiovascular risk, there may be no net benefit from their use. Food sources of calcium appear to produce similar benefits on bone density, although their effects on fracture are unclear. Since food sources have not been associated with adverse cardiovascular effects, they may be preferable. Available evidence suggests that other osteoporosis treatments are still effective without calcium co-administration.

Pulse wave velocity in primary hyperparathyroidism and effect of surgical therapy

The study was aimed at investigating the arterial stiffness assessed by aortic pulse wave velocity (PWV) in the presence of primary hyperparathyroidism (PH), with and without concomitant hypertension. Subsequently, we examined the effect of parathyroidectomy (PTX) on arterial stiffness. A total of 28 patients with PH and concomitant hypertension, and 16 with PH without hypertension were investigated in comparison with 28 essential hypertensive patients and 18 healthy controls, respectively. Patients were matched for age, blood pressure (BP), body mass index, lipid profile and fasting glucose. Six months after PTX, 15 patients were examined again (hypertensive as well as normotensive). PWV was obtained using the SphygmoCor applanation tonometer (AtCor Medical, West Ryde, Australia). PWV was significantly higher in patients with PH and hypertension when compared with patients with essential hypertension (10.1 vs. 8.5 ms(-1), P=0.013). PWV remained significant even after adjustment for age and BP (P=0.02). Similarly, PWV was significantly higher in PH patients without hypertension in comparison with healthy controls (7.6 vs. 5.8 ms(-1), P<0.001). Six months after surgery, in addition to a normalization of calcium metabolism, a significant decrease in systolic BP (131 vs. 123 mmHg, P=0.004) and PWV (9.1 vs. 8.5 ms(-1), P=0.024) was observed. After adjusting for BP reduction, the decrease in PWV appeared non-significant. Our data indicate that PH increases PWV as a marker of arterial stiffness, in both hypertensive and non-hypertensive patients. However, neither the calcium serum level nor the parathyroid hormone level has been associated with PWV. Specific treatment by PTX significantly decreases PWV, which may be determined primarily by improved BP control after surgery.

Reduced coronary flow reserve in patients with primary hyperparathyroidism: a study by G-SPECT myocardial perfusion imaging

PURPOSE

The mechanisms underlying increased cardiovascular risk in primary hyperparathyroidism (pHPT) have not been fully defined. Recently, this issue has become the subject of renewed interest due to the increasing evidence that the endothelium and vascular wall are targets for parathyroid hormone (PTH). The aim of this study was to measure regional coronary flow reserve (CFR) to determine whether the vascular damage induced by pHPT extends to affect the coronary microvascular function.

METHODS

A total of 22 pHPT patients without a history of coronary artery disease and 7 age-matched control subjects were recruited. Dipyridamole myocardial blood flow (MBF) was assessed using 99mTc-sestamibi by measuring first-transit counts in the pulmonary artery and myocardial count rate from G-SPECT images. Baseline MBF was estimated 2 h later according to the same procedure. Regional CFR was defined as the ratio between dipyridamole and baseline MBF using a 17-segment left ventricular model.

RESULTS

Three pHPT patients showed reversible perfusion defects and were excluded from the analysis. In the remaining 19, CFR was significantly lower with respect to the control subjects (1.88±0.64 vs. 3.36±0.66, respectively; p<0.01). Moreover, patients studied for more than 28 months from pHPT diagnosis showed lower CFR values than the others (1.42±0.18 vs. 2.25±0.64, respectively; p<0.01). Consequently, the time from diagnosis to the nuclear study showed a reasonable correlation with the degree of CFR impairment (Spearman's rho -0.667, p<0.02).

CONCLUSION

pHPT is associated with a significant dysfunction of the coronary microcirculation. This disorder might contribute to the high cardiovascular risk of conditions characterized by chronic elevations in serum PTH levels.

Carotid vascular abnormalities in primary hyperparathyroidism

CONTEXT

Data on the presence, extent, and reversibility of cardiovascular disease in primary hyperparathyroidism (PHPT) are conflicting.

OBJECTIVE

This study evaluated carotid structure and function in PHPT patients compared with population-based controls.

DESIGN

This is a case-control study.

SETTING

The study was conducted in a university hospital metabolic bone disease unit.

PARTICIPANTS

Forty-nine men and women with PHPT and 991 controls without PHPT were studied.

OUTCOME MEASURES

We measured carotid intima-media thickness (IMT), carotid plaque presence and thickness, and carotid stiffness, strain, and distensibility.

RESULTS

IMT, carotid plaque thickness, carotid stiffness, and distensibility were abnormal in PHPT patients, and IMT was higher in patients than controls (0.959 vs. 0.907 mm, P < 0.0001). In PHPT, PTH levels, but not calcium concentration, predicted carotid stiffness (P = 0.04), strain (P = 0.06), and distensibility (P = 0.07). Patients with increased carotid stiffness had significantly higher PTH levels than did those with normal stiffness (141 +/- 48 vs. 94.9 +/- 44 pg/ml, P = 0.002), and odds of abnormal stiffness increased 1.91 (confidence interval = 1.09-3.35; P = 0.024) for every 10 pg/ml increase in PTH, adjusted for age, creatinine, and albumin-corrected calcium.

CONCLUSIONS

Mild PHPT is associated with subclinical carotid vascular manifestations. IMT, a predictor of cardiovascular outcomes, is increased. Measures of carotid stiffness are associated with extent of PTH elevation, suggesting that those with more severe PHPT may have impaired vascular compliance and that PTH, rather than calcium, is the mediator.

Endothelial function and endothelial nitric oxide synthase intron 4a/b polymorphism in primary hyperparathyroidism

BACKGROUND AND AIM

Patients with symptomatic primary hyperparathyroidism (pHT) have increased cardiovascular morbidity and mortality. Endothelial nitric oxide synthase (eNOS) intron 4a/b polymorphism is associated with coronary artery disease and hypertension in various populations. Our aim is to evaluate endothelial function in patients with pHT during pre-operative hypercalcemic and post-operative normocalcemic periods and to determine whether intron 4a/b polymorphism of eNOS gene influences endothelial function.

SUBJECTS AND METHODS

Forty patients with pHT (age 48.48+/-11.64 yr) were examined pre-operatively and reexamined 5.8+/-1.9 months after parathyroidectomy. Forty-three healthy subjects (age 47.13+/-8.14 yr) were served as control group. Endothelial function was determined by flow-mediated dilation of brachial artery (FMD). eNOS4a/b polymorphism was detected by polymerase chain reaction.

RESULTS

FMD was significantly lower in patients pre-operatively compared with controls (8.48+/-1.78% vs 19.49+/-2.34%, p<0.001). FMD improved significantly after parathyroidectomy (16.19+/-2.16%, p<0.001 compared with pre-operative measurements), but was still significantly lower than controls (p<0.001). The distribution of eNOS4a/b genotype frequencies was not significantly different between patients and controls. Logistic regression analysis showed that increased serum calcium (>2.47 mmol/l) and PTH concentrations (>7.75 pmol/l) were significant independent predictors of lower FMD (<16.7%). ENOS4a/b polymorphism did not enter in this model.

CONCLUSION

Impaired endothelial function in patients with pHT improves after successful parathyroid surgery. No compelling data are evident to suggest that eNOS4a/b polymorphism modifies the endothelial function in patients with pHT.

Increased plasminogen activator inhibitor-1, decreased tissue factor pathway inhibitor, and unchanged thrombin-activatable fibrinolysis inhibitor levels in patients with primary hyperparathyroidism

BACKGROUND AND OBJECTIVES

Primary hyperparathyroidism (PHPT) is associated with increased cardiovascular mortality and morbidity. Little is known about hemostatic features of patients with PHPT. To our knowledge, plasma tissue factor pathway inhibitor (TFPI) and thrombin-activatable fibrinolysis inhibitor (TAFI) levels in these patints have not been investigated. Therefore, the main purpose of this study was to evaluate the markers of endogenous coagulation/fibrinolysis, including TFPI and TAFI, and to investigate the relationships between serum calcium and PTH and these hemostatic parameters in patients with PHPT.

DESIGN AND METHODS

Twenty-four patients with PHPT and 20 age-, sex-, and-weight-matched healthy controls were included in the study. Tissue plasminogen activator (t-PA), tissue plasminogen activator inhibitor-1 (PAI-1), TFPI, and TAFI were measured. The relationships between serum calcium, phosphorus, and PTH and these hemostatic parameters were examinated.

RESULTS

Compared with the control subjects, t-PA, PAI-1, and PAI-1/t-PA ratios were significantly increased in patients with PHPT (P<0.0001), whereas TFPI levels were significantly decreased (P<0.0001). Plasma TAFI Ag levels did not significantly change in patients with PHPT compared with the controls. In patients with PHPT, serum phosphorus was negatively correlated with plasma PAI-1 Ag levels and PAI-1/t-PA ratio (r: -0.453, P<0.05; r: -0.580, P<0.01 respectively). There was a positive correlation between Cl/P ratio and plasma PAI-1 levels and PAI-1/t-PA ratio (r: 0.434, P<0.05; r: 0.528, P<0.05 respectively). iPTH was positively correlated with plasma PAI-1/t-PA ratio (r: 0.429, P<0.05).

INTERPRETATION AND CONCLUSIONS

In conclusion, we found some important differences in the hemostatic parameters between the patients with PHPT and healthy controls. Increased PAI-1, PAI-1/t-PA ratios and decreased TFPI levels in these patients represent a potential hypercoagulable and hypofibrinolytic state, which might augment the risk for atherosclerotic and atherothrombotic complications. This condition may contribute to the excess mortality due to cardiovascular disease seen in patients with PHPT.

Presentation of asymptomatic primary hyperparathyroidism: proceedings of the third international workshop

BACKGROUND

At the Third International Workshop on Asymptomatic Primary Hyperparathyroidism (PHPT) in May 2008, recent data on the disease were reviewed. We present the results of a literature review on issues arising from the clinical presentation and natural history of PHPT.

METHODS

Questions were developed by the International Task Force on PHPT. A comprehensive literature search for relevant studies was reviewed, and the questions of the International Task Force were addressed by the Consensus Panel.

CONCLUSIONS

1) Data on the extent and nature of cardiovascular involvement in those with mild disease are too limited to provide a complete picture. 2) Patients with mild PHPT have neuropsychological complaints. Although some symptoms may improve with surgery, available data remain inconsistent on their precise nature and reversibility. 3) Surgery leads to long-term gains in spine, hip, and radius bone mineral density (BMD). Because some patients have early disease progression and others lose BMD after 8-10 yr, regular monitoring (serum calcium and three-site BMD) is essential in those followed without surgery. Patients may present with normocalcemic PHPT (normal serum calcium with elevated PTH concentrations; no secondary cause for hyperparathyroidism). Data on the incidence and natural history of this phenotype are limited. 4) In the absence of kidney stones, data do not support the use of marked hypercalciuria (>10 mmol/d or 400 mg/d) as an indication for surgery for patients. 5) Patients with bone density T-score -2.5 or less at the lumbar spine, hip, or distal one third radius should have surgery.

Cardiovascular aspects of primary hyperparathyroidism

Data concerning the cardiovascular manifestations of primary hyperparathyroidism (PHPT) are inconsistent, which is due, in part, to the decrease in disease severity over the last several decades. In areas where patients tend to be more symptomatic, data support the presence of cardiovascular findings including myocardial and vascular calcification as well as increased cardiovascular mortality. Data from the cohorts in whom the disease is characterized by mild hypercalcemia, suggest that clinically overt cardiovascular manifestations are unusual in PHPT. Recent data, however, support the presence of subtle cardiovascular manifestations in mild disease, such as changes in endothelial function as well as increased vascular stiffness and perhaps diastolic dysfunction. Left ventricular hypertrophy is a more consistent finding across a spectrum of disease severity, though this finding may be related to hypertension, which has long been associated with PHPT.

Parathyroid hormone and the cardiovascular system

The classical actions of parathyroid hormone (PTH) are well recognized, but its effects on other target tissues, such as the cardiovascular system, are less appreciated. Several studies have evaluated the effects of PTH in patients with primary hyperparathyroidism in order to understand potential cardiovascular effects in terms of hypertension, cardiovascular mortality, left ventricular function, and endothelial function. We review these studies and evaluate the cellular mechanisms that may affect these outcomes.