Higher Parathyroid Hormone Concentrations Research Articles

Hypertension and other cardiovascular risk factors are associated with vitamin D deficiency in an urban Chinese population: A short report

There is debate concerning the association of 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) with cardiovascular disease (CVD) risk factors. As both hypertension and vitamin D deficiency are increasingly important public health concerns in China, we investigated these associations in 566 Macao residents.The aim was to investigate the association of serum 25OHD and PTH concentrations with CVD risk factors (hypertension, high pulse rate, abnormal blood lipids). The data were stratified by age, sex, and blood pressure (BP) medication use. Multiple linear regression analyses were performed to assess associations, adjusting for appropriate confounders.Lower 25OHD concentrations were significantly associated with higher systolic BP (SBP) mmHg (β=−0.07), diastolic BP (DBP) mmHg (β=−0.06) and pulse rate beats/min (β=−0.12), lower high-density lipoprotein (HDL) concentrations nmol/L (β=10.51) and higher triglycerides (TG) nmol/L (β=−2.38). However, the inverse associations with lower 25OHD for higher SBP, DBP, pulse rate and TG were much stronger in those using BP medications, in those who were older, and in females. Higher PTH concentrations were significantly associated with higher low-density lipoprotein (LDL) nmol/L (β=0.77) in the total population and with higher SBP mmHg (β=0.08) in males and those who were older (β=0.09).In conclusion, our major new finding is that lower 25OHD is associated with higher BP especially in those who use BP medications. These results might explain past discrepancies in findings regarding the association of BP and vitamin D and suggest that prospective studies and randomized control trials, in otherwise healthy Chinese populations taking blood pressure medications, are needed to confirm these cross-sectional results.

Relationship between A163G osteoprotegerin gene polymorphism and other osteoporosis parameters in Roma and non-Roma postmenopausal women in eastern Slovakia.

The study was focused on evaluating the possible correlation between biochemical, anthropometric, and genetic indicators of osteoporosis in postmenopausal women. The frequency of genotypes and differences in measured parameters were evaluated within two ethnically different groups of women in Slovakia. The study included 310 postmenopausal women divided into non-Roma and Roma groups. Based on results of densitometry, they were divided into control groups and women with osteoporosis and osteopenia. In all women, a genetic analysis of polymorphism of osteoprotegerin gene promotor region (A163G) was provided along with measurement of indicators of bone tissue metabolism. There is a particularly low incidence of osteoporosis in Roma women. We found a correlation between bone mineral density (BMD), body mass index, and waist and hip circumference in women with osteoporosis and in Roma women with osteopenia. The frequency of the AG genotype was higher in non-Roma women with osteoporosis, but reached only 10.7% in Roma women with osteopenia. While the presence of the G allele in the non-Roma population was accompanied by higher BMD and markers of osteoformation, it was accompanied by significantly higher concentrations of parathyroid hormone in the Roma population. The presence of the AG genotype has a different effect on bone metabolism in two ethnically diverse populations of women in Slovakia. In the general population, the presence of the G allele exhibited protective effects consistent with other studies, but in Roma population this appears to be the allele A. However, this requires a further study for confirmation and more detailed characterization of the differences between populations that have this work indicated.

Fibroblast Growth Factor 23 Regulation by Systemic and Local Osteoblast-Synthesized 1,25-Dihydroxyvitamin D.

Circulating levels of fibroblast growth factor 23 (FGF23) increase during the early stages of kidney disease, but the underlying mechanism remains incompletely characterized. We investigated the role of vitamin D metabolites in regulating intact FGF23 production in genetically modified mice without and with adenine-induced uremia. Exogenous calcitriol (1,25-dihydroxyvitamin D) and high circulating levels of calcidiol (25-hydroxyvitamin D) each increased serum FGF23 levels in wild-type mice and in mice with global deficiency of the Cyp27b1 gene encoding 25-hydroxyvitamin D 1-α-hydroxylase, which produces 1,25-hydroxyvitamin D. Compared with wild-type mice, normal, or uremic mice lacking Cyp27b1 had lower levels of serum FGF23, despite having high concentrations of parathyroid hormone, but administration of exogenous 1,25-dihydroxyvitamin D increased FGF23 levels. Furthermore, raising serum calcium levels in Cyp27b1-depleted mice directly increased FGF23 levels and indirectly enhanced the action of ambient vitamin D metabolites via the vitamin D receptor. In chromatin immunoprecipitation assays, 25-hydroxyvitamin D promoted binding of the vitamin D receptor and retinoid X receptor to the promoters of osteoblastic target genes. Conditional osteoblastic deletion of Cyp27b1 caused lower serum FGF23 levels, despite normal circulating levels of vitamin D metabolites. In adenine-induced uremia, only a modest increase in serum FGF23 levels occurred in mice with osteoblastic deletion of Cyp27b1 (12-fold) compared with a large increase (58-fold) in wild-type mice. Therefore, in addition to the direct effect of high circulating concentrations of 25-hydroxyvitamin D, local osteoblastic conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D appears to be an important positive regulator of FGF23 production, particularly in uremia.

Plasma Parathyroid Hormone Is Independently Related to Nocturnal Blood Pressure in Hypertensive Patients: The Styrian Hypertension Study.

High parathyroid hormone (PTH) has been linked with high blood pressure (BP), but the relationship with 24-hour ambulatory blood pressure monitoring is largely unknown. The authors therefore analyzed cross-sectional data of 292 hypertensive patients participating in the Styrian Hypertension Study (mean age, 61±11 years; 53% women). Median plasma PTH (interquartile range) determined after an overnight fast was 49 pg/mL (39-61), mean daytime BP was 131/80±12/9 mm Hg, and mean nocturnal BP was 115/67±14/9 mm Hg. In multivariate regression analyses adjusted for BP and PTH-modifying parameters, PTH was significantly related to nocturnal systolic and diastolic BP (adjusted β-coefficient 0.140 [P=.03] and 0.175 [P<.01], respectively). PTH was not correlated with daytime BP readings. These data suggest a direct interrelationship between PTH and nocturnal BP regulation. Whether lowering high PTH concentrations reduces the burden of high nocturnal BP remains to be shown in future studies.

Continuous Positive Airway Pressure Treatment Increases Serum Vitamin D Levels in Male Patients with Obstructive Sleep Apnea.

Recent studies report a link between obstructive sleep apnea (OSA) syndrome, low vitamin D levels, and high parathyroid hormone (PTH) concentrations. The aim of the current study is to evaluate the effect of 7-night continuous positive airway pressure (CPAP) therapy on serum vitamin D, PTH, and calcium levels in patients with severe OSA syndrome. Patients with severe OSA were enrolled into the study and compared to control subjects. Patients with OSA underwent CPAP therapy for 7 nights and were consequently divided into responders (OSA-R, mean residual AHI < 5/h) and nonresponders (OSA-nR, mean residual AHI > 5/h). Serum vitamin D, PTH, and calcium levels were measured at baseline in patients with severe OSA (apnea-hypopnea index > 30/h) and control subjects. Patients with OSA underwent a final morning blood sample after 7-night CPAP therapy. We enrolled 90 patients with OSA into the study (65 OSA-R and 25 OSA-nR) compared to 32 control subjects. At baseline, lower vitamin D and higher PTH levels were detected in the OSA group compared to controls. After 7-night CPAP therapy, male OSA-R patients showed a significant increase in vitamin D levels. Conversely, female OSA-R patients did not show the same increase in vitamin D levels. It was also observed that OSA-nR subjects did not show modifications of serum markers after nCPAP-therapy. The study demonstrates that short-term nCPAP treatment is able to promote the recovery of vitamin D homeostasis in male patients with OSA. The mediation of sexual hormones in regulating vitamin D is a possible explanation of the lack of recovery of vitamin D homeostasis in female patients with OSA as it often affects postmenopausal women.

Rapid calcitriol increase and persistent calcidiol insufficiency in the first 6 months after kidney transplantation.

Vitamin D deficiency or insufficiency is prevalent in kidney transplant recipients. Little is known about post-transplantation changes in vitamin D forms, which are essential for bone health and other health outcomes. The aim was to measure the levels of calcidiol and calcitriol during the first 6 months after kidney transplantation and examine their relation with other bone mineral metabolic parameters. A prospective study was performed on 98 patients recruited between April 2010 and June 2011. Calcidiol and calcitriol levels were measured at baseline and at days 15, 30, 90, and 180 after kidney transplantation. Serum calcidiol levels remained persistently low: 14.3 (9-22) ng/ml at baseline and 16.3 (10.1-20.6) ng/ml at 6 months (P=0.641). At 6 months, calcidiol levels showed an inverse correlation with simultaneously measured parathyroid hormone levels. Calcidiol showed a trend to be higher in patients transplanted in spring but with no statistically significant difference. Calcitriol levels increased from 17 (13-23.7) pg/ml at baseline to 24 (16-32) pg/ml (P=0.002) in the first 2 weeks after transplantation and reached 37 (25-50) pg/ml (P=0.000) after 6 months. During the follow-up, calcitriol levels showed a significant inverse correlation with baseline fibroblast growth factor-23 levels. At month 6, calcitriol levels were inversely correlated with baseline fibroblast growth factor-23 levels and directly correlated with calcidiol levels. In most patients, calcidiol levels remain low 6 months after kidney transplantation, whereas calcitriol levels rapidly return to normal. Lower calcidiol blood levels promoted lower calcitriol blood levels and higher parathyroid hormone concentrations.

A novel, ultrarapid parathyroid hormone assay to distinguish parathyroid from nonparathyroid tissue

Frozen section is the gold standard for distinguishing parathyroid tissue from lymph nodes, thyroid nodules, or fat during parathyroidectomy and thyroidectomy. Although a very accurate procedure, it can be time-consuming and costly. We hypothesize that the extremely high concentrations of parathyroid hormone (PTH) in parathyroid tissue allow for modification of a standard PTH assay that would distinguish parathyroid from nonparathyroid tissue in substantially less time than frozen section or any currently available PTH assay. A prospective, single-institution study using a modified PTH assay protocol and a manual luminometer was undertaken by testing 20 parathyroid adenomas and 9 control tissues. Analyses were performed simultaneously by the modified PTH protocol and the conventional intraoperative PTH assay. PTH luminescence values from parathyroid tissue and control tissue aspirates were significantly different at 60 seconds (P = .015). ROC curve analysis showed the assay to be 100% sensitive and 100% specific in differentiating parathyroid from nonparathyroid tissue. Our novel PTH assay accurately and reliably differentiates parathyroid from nonparathyroid tissue within 60 seconds of measurement onset. This assay provides a great advantage in time savings compared with frozen section as well as any currently existing PTH assays.

Comparative Mortality–Predictability Using Alkaline Phosphatase and Parathyroid Hormone in Patients on Peritoneal Dialysis and Hemodialysis

In hemodialysis (HD) patients, serum alkaline phosphatase (ALP) and parathyroid hormone (PTH) derangements are associated with mortality, but outcome-predictability using ALP and PTH in peritoneal dialysis (PD) patients remains uncertain. In a cohort of 9244 adult PD patients from a large national dialysis organization (entry period 2001 - 2006, with follow-up through 2009), we used multivariable Cox models adjusted for case-mix and laboratory covariates to examine the associations of time-averaged ALP and PTH with all-cause mortality. We then compared mortality-predictability using ALP and PTH in 9244 PD and 99 323 HD patients. In PD patients, ALP concentrations exceeding 150 U/L were associated with increased mortality (reference ALP: 70 to <90 U/L). Hazard ratios (HRs) and 95% confidence intervals (CIs) were 1.18 (1.03 to 1.36), 1.27 (1.08 to 1.50), 1.49 (1.23 to 1.79), and 1.35 (1.19 to 1.53) for ALP concentrations of 150 to <170 U/L, 170 to <190 U/L, 190 to <210 U/L, and ≥210 U/L respectively. In contrast, we observed a U-shaped association between PTH concentration and death risk in PD patients, with PTH concentrations of less than 200 pg/mL and 700 pg/mL or more associated with increased mortality (reference PTH: 200 to <300 pg/mL). Hazard ratios and 95% CIs were 1.25 (1.12 to 1.41), 1.12 (1.02 to 1.23), 1.06 (0.96 to 1.18), 1.09 (0.97 to 1.24), 1.12 (0.97 to 1.29), 1.18 (0.99 to 1.40), and 1.23 (1.09 to 1.38) for PTH concentrations of <100 pg/mL, 100 to <200 pg/mL, 300 to <400 pg/mL, 400 to <500 pg/mL, 500 to <600 pg/mL, 600 to <700 pg/mL, and ≥700 pg/mL respectively. Compared with PD patients having serum concentrations of ALP and PTH within reference ranges, patients on HD experienced increased mortality across all ALP and PTH concentrations, particularly those in the lowest and highest categories. In summary, higher ALP concentrations are associated with increased mortality, and lower and higher PTH concentrations are both associated with death risk in PD patients. The utility of ALP in the management of chronic kidney disease mineral bone disorders in PD patients warrants further study.

Predictive Parameters of Accelerated Muscle Loss in Men—MINOS Study

BackgroundAging-related muscle loss is a public health problem. We investigated the association of lifestyle and hormonal factors with a prospectively assessed muscle loss in older men. MethodsAmong 608 home-dwelling men, aged 60-85 (mean 68) years, lifestyle and health status were evaluated through a questionnaire. Appendicular skeletal muscle mass was estimated using dual-energy x-ray absorptiometry and calculated as the sum of lean mass of the 4 limbs. Free testosterone concentration was calculated using concentrations of total testosterone and sex hormone-binding globulin. Longitudinal data were analyzed by hierarchical models. ResultsAverage muscle loss was 0.63 ± 0.05%/year. The results of our multivariable adjusted analyses showed that muscle loss was higher in men whose leisure physical activity was <15 hours/week versus ≥15 hours/week (−0.76 vs −0.57%/year). Age-related acceleration of muscle loss was greater in men with lower total testosterone levels (<10 vs ≥10 nmol/L: −0.10 vs −0.07%/year/year of age at baseline [age]). Men with lower free testosterone (<75 vs ≥75 pmol/L) had greater age-related acceleration of muscle loss (−0.12 vs −0.08%/year/age). Higher parathyroid hormone concentrations were associated with greater age-related acceleration of muscle loss (≥45 vs <45 pg/mL −0.14 vs −0.12%/year/age). Men with type 2 diabetes had higher age-related acceleration of muscle loss versus men without diabetes (−0.08 vs −0.03%/year/age) (All P values are <.05). ConclusionIn elderly men, low leisure physical activity, type 2 diabetes, low total and free testosterone, and elevated parathyroid hormone concentrations are associated with greater age-related acceleration of muscle loss. These factors are likely to represent real determinants of aging-related muscle loss in men.

Association of 25-Hydroxyvitamin D and Parathyroid Hormone With Incident Hypertension: MESA (Multi-Ethnic Study of Atherosclerosis)

This study investigated whether lower 25-hydroxyvitamin D and higher parathyroid hormone concentrations are associated with incident hypertension. Disturbances in vitamin D metabolism are plausibly related to hypertension. MESA (Multi-Ethnic Study of Atherosclerosis) is a community-based, prospective cohort with baseline measurements obtained between 2000 and 2002. We studied 3,002 men and women free of prevalent cardiovascular disease and hypertension, age 45 to 84 years at baseline. Serum 25-hydroxyvitamin D and intact parathyroid hormone were measured from previously frozen baseline samples using liquid chromatography-mass spectroscopy and a 2-site immunoassay, respectively. We used a complementary log-log model with interval censoring to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for 25-hydroxyvitamin D and parathyroid hormone concentrations with incident hypertension through 2010. During a median follow-up of 9.0 years, 41% of the cohort (n = 1,229) developed hypertension. Mean serum 25-hydroxyvitamin D was 26.3 ± 11.2 ng/ml and mean parathyroid hormone was 41.2 ± 17.3 pg/ml. Compared with 25-hydroxyvitamin D ≥30 ng/ml, 25-hydroxyvitamin D <20 ng/ml was associated with a greater hypertension risk (HR: 1.28 [95% CI: 1.09 to 1.50]), although the association was attenuated and not statistically significant after adjusting for potential confounders (HR: 1.13 [95% CI: 0.96 to 1.33]). Compared with parathyroid hormone <33 pg/ml, parathyroid hormone ≥65 pg/ml was associated with a significantly greater risk of hypertension (HR: 1.27 [95% CI: 1.01 to 1.59]) after adjusting for potential confounders. Lower 25-hydroxyvitamin D concentrations were not associated with a greater risk of incident hypertension. Higher serum parathyroid hormone concentrations showed a significant, but statistically marginal, relationship to the development of hypertension. These findings will require further confirmation. (Multi-Ethnic Study of Atherosclerosis; NCT00005487).

Vitamin D and Its Relationship with Markers of Bone Metabolism in Healthy Asian Women

In this study, we aimed to determine the normal ranges of 25-hydroxy-vitamin D(3) (25-OHD(3)), parathyroid hormone (PTH), and the markers of bone turnover, procollagen type 1 N propeptide (P1NP) and C-terminal cross-linked telopeptide of type 1 collagen (CTX), in normal healthy women in Singapore, and to explore the relationship between vitamin D, PTH, and these markers of bone turnover in the women. One hundred and ninety-seven healthy women, aged 25 to 60, were selected from a hospital staff health screening program; 68% were Chinese, 18% Malay, and 14% Indian. P1NP, CTX, and 25-OHD(3) were measured using the Roche Cobas® electrochemiluminescence immunoassay. Serum PTH was measured using the Siemens ADVIA Centaur® immunoassay. Sixty-five percent had 25-OHD(3) concentrations <50 nmol/l. Vitamin D insufficiency (25-OHD(3) < 50 nmol/l) was more prevalent in Malays (89%) and Indians (82%) compared to Chinese (56%). There was no correlation between vitamin D and age. PTH positively correlated with age, and Malays and Indians had higher PTH concentrations than Chinese. There was an inverse correlation between PTH and 25-OHD(3), but no threshold of 25-OHD(3) concentrations at which PTH plateaued. The bone turnover markers P1NP and CTX inversely correlated with age but were not different between ethnic groups. CTX and P1NP exhibited good correlation, however, there was no significant correlation between 25-OHD(3) or PTH concentrations and the bone turnover markers P1NP and CTX. Healthy women in Singapore have a high prevalence of vitamin D insufficiency. Vitamin D insufficiency was more prevalent in Malays and Indians compared to Chinese.

Abstract P036: Parathyroid Hormone is Associated with All-Cause and Cardiovascular Mortality: The Hoorn Study

Introduction Higher parathyroid hormone (PTH) concentrations have been associated with increased cardiovascular disease (CVD) mortality, although data in the general population are scarce. Hypothesis We hypothesize that higher serum PTH concentrations are associated with all-cause and CVD mortality in a prospective, population-based cohort of older men and women. Methods We included 633 participants of the Hoorn Study, a population-based cohort with oversampling of subjects with impaired glucose regulation; mean age 70.1±6.6 years, 50.7% female. Serum intact PTH concentrations were measured using a 2-site immunoassay. Outcomes were all-cause and CVD mortality based on clinical files and coded according to the ICD-9. We used Cox-regression to estimate survival curves and hazard ratios (HR 95% CI) for all-cause and CVD mortality adjusted for potential confounders using season-specific PTH quartiles. Results During a median follow-up of 7.8 years, 112 participants died, of which 26 deaths (23%) were due to CVD. Survival curves showed an impaired survival for all-cause (Log-rank p=0.054) and CVD mortality (Log-rank p=0.022) for people in the highest PTH quartile (Figure 1). In a multivariate model adjusted for age, sex, smoking, education level, BMI, glucose status, systolic blood pressure, anti-hypertensive drug use, the highest PTH quartile was associated with higher all-cause mortality; HR 1.98 (1.08, 3.64). Kidney function (estimated glomerular filtration rate and micro-albuminuria) attenuated the PTH risk association, but risk persisted; HR 1.93 (95% CI 1.04, 3.58). The results for CVD mortality showed a similar pattern, although the association was only significant in a threshold model (Quartile 4 vs. Quartile 1-3) HR 2.56 (1.11, 5.94). Conclusion In conclusion, among older men and women, higher PTH concentrations are associated with higher mortality risk. We suggest to evaluate whether individuals with high PTH concentrations benefit from therapeutic approaches targeted to decrease PTH concentrations.

Uremic Restless Legs Syndrome (RLS) and Sleep Quality in Patients With End-Stage Renal Disease on Hemodialysis: Potential Role of Homocysteine and Parathyroid Hormone

Background: The aetiology of uremic restless legs syndrome (RLS) remains unclear. Our research investigated whether an elevated plasma concentration of the excitatory amino acid homocysteine might be associated with RLS occurrence in patients with chronic renal insufficiency on hemodialysis. Methods: Total plasma homocysteine as well as creatinine, urea, folate, parathyroid hormone, hemoglobin, iron, ferritin, phosphate, calcium, magnesium, and albumin levels were compared between 26 RLS-affected (RLSpos) and 26 non-affected (RLSneg) patients on chronic hemodialysis. We further compared subjective sleep quality between RLSpos and RLSneg patients using the Pittsburgh-Sleep-Quality-Index and investigated possible relationships between laboratory parameters and sleep quality. Results: Taking individual albumin concentrations into account, a significant positive correlation between total plasma homocysteine and RLS occurrence was observed (r= 0.246; p=0.045). Sleep quality was significantly more reduced in RLSpos compared to RLSneg patients and RLS severity correlated positively with impairment of sleep quality. Bad sleep quality in all patients was associated with higher concentrations of parathyroid hormone. Conclusion: Our results suggest a possible aetiological role of homocysteine in uremic RLS. They confirm that uremic RLS is an important factor causing sleep impairment in patients on hemodialysis. Higher parathyroid hormone levels might also be associated with bad sleep quality in these patients.

Short-term teriparatide treatment does not affect NT-proBNP, a marker of cardiac disease

Background. Teriparatide (Parathyroid hormone (PTH) 1–34) has been shown to increase bone mineral density (BMD) and reduce the risk of vertebral fractures when given intermittently. In contrast primary hyperparathyroidism (PHPT) is associated with increased bone loss. Moreover an increased occurrence of cardiovascular disease (CVD) is seen in PHPT patients. The N-terminal fragment of the pro-peptide of Brain Natriuretic peptide (NT-proBNP), a risk marker of CVD, has been shown to be elevated in PHPT patients, indicating that continuously high concentrations of PTH affect the heart. Therefore the aim of this study was to investigate whether teriparatide treatment is associated with changes in plasma NT-proBNP. Methods. A total of 42 patients receiving teriparatide treatment were included in the study. Blood samples were taken at baseline, and after 1, 3 and 6 months of treatment. Plasma concentrations of NT-proBNP were measured. Plasma concentrations of ionized calcium, PTH and alkaline phosphatase (ALP) were also analyzed, and BMD for the lumbar spine and total hip was recorded at baseline and after 6 months. Results. Data from 10 men and 32 women, mean age 68 years, were included in the analysis. No effect of teriparatide on plasma concentrations of NT-proBNP was observed at any time points. Ionized calcium and ALP concentrations in the plasma increased after 6 months of treatment, whereas PTH concentrations decreased. Spine BMD T-score was significantly increased after 6 months of treatment. Conclusion. After 6 months of treatment with teriparatide, it did not change the concentration of NT-proBNP in plasma, suggesting that intermittent exposure to therapeutic levels of teriparatide does not affect heart function.

Extremely high parathyroid hormone concentrations associated with pityriasis rubra pilaris and monoclonal gammopathy of unknown significance: A clinical dilemma

We present a case with extremely high parathyroid hormone (PTH) concentrations in the order of hundred thousands accompanied by dermatological and hematological diseases. After several diagnostic interventions, no malignancy could be demonstrated except monoclonal gammopathy of unknown significance. The dermatological findings were taken to be manifestations of the hematological disease. Since the first serum intact PTH concentration of the patient was found to be higher than 2500pg/ml, dilution study was performed and found to be 215,977pg/ml. The high concentration of serum PTH was taken to be falsely high due to assay interference. This concentration was checked from three different paths; a test for linear dilution was performed, the test was repeated with another method and the sample was treated to remove or inhibit interfering substances. The results were compatible with endogenous antibody interference, presumed to be a result of monoclonal gammopathy. The extremely high PTH concentrations were not only due to assay interference, but also secondary hyperparathyroidism, which was evident by the decrease in PTH concentrations with calcium and vitamin D treatments.

Relationship Among Endothelial Response to Hyperemia, Bone Marrow-Derived Progenitor Cells, and Parathyroid Hormone in Renal Transplantation

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. 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. 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. 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.

Vitamin D, Parathyroid Hormone, and Sudden Cardiac Death

Recent studies have demonstrated greater risks of cardiovascular events and mortality among persons who have lower 25-hydroxyvitamin D (25-OHD) and higher parathyroid hormone (PTH) levels. We sought to evaluate the association between markers of mineral metabolism and sudden cardiac death (SCD) among the 2312 participants from the Cardiovascular Health Study who were free of clinical cardiovascular disease at baseline. We estimated associations of baseline 25-OHD and PTH concentrations individually and in combination with SCD using Cox proportional hazards models after adjustment for demographics, cardiovascular risk factors, and kidney function. During a median follow-up of 14 years, there were 73 adjudicated SCD events. The annual incidence of SCD was greater among subjects who had lower 25-OHD concentrations, 2 events per 1000 for 25-OHD ≥20 ng/mL and 4 events per 1000 for 25-OHD <20 ng/mL. Similarly, SCD incidence was greater among subjects who had higher PTH concentrations, 2 events per 1000 for PTH <65 pg/mL and 4 events per 1000 for PTH ≥65 pg/mL. Multivariate adjustment attenuated associations of 25-OHD and PTH with SCD. Finally, 267 participants (11.7% of the cohort) had high PTH and low 25-OHD concentrations. This combination was associated with a >2-fold risk of SCD after adjustment (hazard ratio: 2.19 [95% CI: 1.17-4.10]; P=0.017) compared with participants with normal levels of PTH and 25-OHD. The combination of lower 25-OHD and higher PTH concentrations appears to be associated independently with SCD risk among older adults without cardiovascular disease.

Racial differences in the relationship between vitamin D, bone mineral density, and parathyroid hormone in the National Health and Nutrition Examination Survey

It is unclear whether optimal levels of 25-hydroxyvitamin D (25(OH)D) in whites are the same as in minorities. In adult participants of NHANES, the relationships between 25(OH)D, bone mineral density (BMD), and parathyroid hormone (PTH) differed in blacks as compared to whites and Mexican-Americans, suggesting that optimal 25(OH)D levels for bone and mineral metabolism may differ by race. Blacks and Hispanics have lower 25-hydroxyvitamin D concentrations than whites. However, it is unclear whether 25(OH)D levels considered "optimal" for bone and mineral metabolism in whites are the same as those in minority populations. We examined the relationships between 25(OH)D and parathyroid hormone in 8,415 adult participants (25% black and 24% Mexican-American) in the National Health and Nutrition Examination Surveys 2003-2004 and 2005-2006; and between 25(OH)D and bone mineral density in 4,206 adult participants (24% black and 24% Mexican-American) in the 2003-2004 sample. Blacks and Mexican-Americans had significantly lower 25(OH)D and higher PTH concentrations than whites (P < 0.01 for both). BMD significantly decreased (P < 0.01) as serum 25(OH)D and calcium intake declined among whites and Mexican-Americans, but not among blacks (P = 0.2). The impact of vitamin D deficiency (25(OH)D ≤ 20 ng/ml) on PTH levels was modified by race/ethnicity (P for interaction, 0.001). Whereas inverse relationships between 25(OH)D and PTH were observed above and below a 25(OH)D level of 20 ng/ml in whites and Mexican-Americans, an inverse association between 25(OH)D and PTH was only observed below this threshold in blacks, with the slope of the relationship being essentially flat (P = 0.7) above this cut-point, suggesting that PTH may be maximally suppressed at lower 25(OH)D levels in blacks than in whites or Mexican-Americans. The relationships between 25(OH)D, BMD, and PTH may differ by race among US adults. Whether race-specific ranges of optimal vitamin D are needed to appropriately evaluate the adequacy of vitamin D stores in minorities requires further study.

Parathyroid carcinoma: a 16-year experience in a single institution

This study aims to describe our experiences of parathyroid carcinoma. The data of clinicopathological features, surgical treatment and outcomes of seven cases of parathyroid carcinoma among 171 patients who underwent surgery for primary hyperparathyroidism over a 16-year period were analyzed. The major symptoms at the diagnosis included a neck mass in three cases and multiple bone pain in five. Two patients were asymptomatic. No remarkable increases of serum calcium levels were noted in the patients, but serum parathyroid hormone (PTH) concentrations were high in most of the patients (4 of 5 in available). A variety of imaging studies including ultrasonography, sestamibi scan, and computed tomography scan were helpful in identifying the abnormal parathyroid glands, but not specific for the diagnosis of parathyroid carcinoma. In most patients, the parathyroid carcinomas were suspected at the time of neck exploration, and confirmed by final histopathologic examinations. All patients underwent complete surgical excision with curative intent. During the follow-up period, one patient developed lung metastases 6 years later and the other one died of unrelated cause. Preoperative diagnosis of parathyroid carcinoma is difficult, but operative findings are helpful in the diagnosis. The optimal surgical treatment is en block radical resection including adjacent structures when parathyroid carcinoma is suspected. Unusually, although our patients presented with high serum PTH concentrations, they had normal or mild elevated serum calcium concentrations. The reason of why should be investigated in future studies.

Prevalence of low serum vitamin D concentration in an urban population of elderly women in Poland

So far only scarce data have been published regarding serum vitamin D concentrations in elderly women in Poland. We aimed to assess prevalence of vitamin D deficiency in a population of women aged 60 to 90 years and living in Warsaw. The study comprised 274 women from the general population (mean age 69.1 -/+5.7 years, body mass index [BMI] 28.9 -/+4.6 kg/m2, serum creatinine concentration 0.7 -/+0.12 mg/dl). Subjects who had been treated with glucocorticoids or antifracture drugs, or supplemented with vitamin D or calcium, were excluded. The study was conducted in winter. Serum vitamin D, calcium, phosphate, and parathyroid hormone (PTH) concentrations were measured. The mean vitamin D concentration was 13.6 ng/ml in the whole examined population. Vitamin D levels above 30 ng/ml were detected in 4% of subjects. Vitamin D insufficiency (20-30 ng/ml) was found in 12.8% of subjects, and its deficiency (<20 ng/ml) in 83.2% of subjects. Vitamin D concentrations in women under and over 70 years of age did not differ significantly. There were no associations of vitamin D concentrations with age, BMI, renal function, or serum calcium concentrations. However, we observed a significant inverse correlation between vitamin D concentrations and PTH. The prevalence of low vitamin D concentrations in an urban population of elderly women in Poland is very high. Lower vitamin D levels are associated with a higher PTH concentration.