Hyperparathyroidism Abstracts 2

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The influence of the progression of secondary hyperparathyroidism on the set point of the parathyroid hormone-calcium curve.
            (Bas et al., 2005) Download
The influence of secondary hyperparathyroidism (2 HPT) on the set point of the parathyroid hormone (PTH)-Ca(2+) curve is controversial. In vitro experiments have shown an increase in the set point. However, clinical studies with hemodialysis patients have provided a variety of results (increases, decreases and no changes in the set point have been reported). The present study was designed to investigate the influence of the progression of 2 HPT on the set point of the PTH-Ca(2+) curve. The PTH-Ca(2+) curve and the expression of parathyroid calcium receptor (CaR mRNA) and vitamin D receptor (VDR mRNA) have been studied in normal rabbits (group I, n=9) and in nephrectomized rabbits (group II, n=18) at two stages after inducing 2 HPT: 2-3 weeks (group IIA) and 5-6 weeks (group IIB). In group I, the set point of the PTH-Ca(2+) curve was 1.63+/-0.03 mM. A progressive hypocalcemia was detected during the evolution of 2 HPT (groups IIA and IIB). Rabbits from group IIA had a significant (P<0.001) decrease in the set point to values of 1.45+/-0.02 mM. However, the set point increased significantly in group IIB (P<0.001) to 1.56+/-0.03 mM. CaR mRNA was similarly decreased in groups IIA (39+/-12%) and IIB (48+/-7%). No changes were detected in VDR mRNA. In conclusion, a reduction in the set point of the PTH-Ca(2+) curve in response to decreased extracellular Ca(2+) was detected in the early phases of 2 HPT. However, with the progression of 2 HPT the set point tended to increase even though extracellular Ca(2+) was markedly decreased. The increase in the set point in the course of 2 HPT seems to be a complex process that cannot be fully explained by changes in parathyroid CaR mRNA or VDR mRNA.

Development of parathyroid gland hyperplasia without uremia: role of dietary calcium and phosphate.
            (Canalejo et al., 2010) Download
Background. Many experimental studies have demonstrated that parathyroid cell proliferation is induced by uremia and further aggravated by hypocalcemia, phosphorus retention and vitamin D deficiency. However, these factors may also promote parathyroid growth without uremia. In the present study, we examined the onset and progression of parathyroid hyperplasia regardless of the uremic setting, a situation that might occur soon during the early renal disease. Thus, the novelty of this work resides in the close examination of the time course for the expected changes in proliferation rates and their association with parathyroid hormone (PTH) release in normal rats under the physiological demands of a high-phosphate diet (HPD) or a low-calcium diet (LCD). Methods. We evaluated the functional response of the parathyroid glands in normal rats to different physiological demands an HPD 0.6% Ca, 1.2% P) and LCD 0.2% Ca, 0.6% P) and compared it with that of uremic rats. Furthermore, we also evaluated the time course for the reversal of high-P and low-Ca-induced parathyroid cell growth and PTH upon normalization of dietary Ca and P intake (0.6% Ca, 0.6% P). Proliferation was measured by flow cytometry and calcium receptor (CaR) and vitamin D receptor (VDR) expression were assessed by qRT-PCR. Results. The pattern in the development of parathyroid hyperplasia by the two dietary models was different. The HPD produced a stronger stimulus than the number of proliferating cells doubled after only 1 day, while the LCD required 5 days to induce an increase; the elevated calcitriol might be a mitigating factor. The increase in cell proliferation was accompanied by a transient down-regulation of VDR expression (higher in the HPD); the expression of CaR was not affected by either diet. Cell proliferation and VDR mRNA levels were restored to control values by Day 15; it is as though the gland had attained a sufficient level of hyperplasia to respond to the PTH challenge. Compared to normal rats, the response of uremic rats to the HPD showed sustained and much higher rates of PTH secretion and cell proliferation and sustained down-regulation of both VDR mRNA and CaR mRNA. Finally, the recovery from the HPD or LCD to a control diet resulted in a rapid restoration of PTH values (1 to 2 days), but the reduction in cell proliferation was delayed (3 to 5 days). Conclusions. Regardless of uremia, a physiological demand to increase the PTH secretion driven either by a high P or a low Ca intake is able to induce a different pattern of parathyroid hyperplasia, which might be aggravated by the down-regulation of VDR expression. The recovery from the HPD or LCD to a control diet results in a more rapid reduction in PTH than in cell proliferation.

Association between parathyroid hormone levels and inflammatory markers among US adults.
            (Cheng et al., 2014) Download
BACKGROUND AND AIMS:  High levels of parathyroid hormone (PTH) appear to be associated with an increased mortality. Previous studies concerning the relationship of inflammatory markers with hyperparathyroidism have yielded inconsistent results. This study investigated whether serum PTH concentrations were independently associated with several inflammatory markers among the US adults. MATERIALS AND METHODS:  Using data from the National Health and Nutrition Examination Survey, we examined the relation between serum PTH and C-reactive protein (CRP), red cell distribution width (RDW), and platelet-to-lymphocyte ratio (PLR) levels with weighted linear regression. Additionally, we examined the relation with increased modified Glasgow Prognostic Score (mGPS) by using weighted logistic regression. RESULTS:  CRP, RDW, and PLR values increased with increasing serum PTH concentration. After extensively adjusting for covariates, CRP and RDW increased linearly and across PTH categories (all P < 0.001), while PLR marginally increased (P = 0.190 and P = 0.095 using PTH as a categorical and continuous variable, resp.). The odds ratio of increased mGPS was 1.11 and 1.31 across PTH categories and with increasing PTH levels continuously. CONCLUSION:  These nationally representative data indicate that serum PTH levels are independently associated with several inflammatory markers in the US population. The casual relationship between PTH levels and inflammation remains to be elucidated.

Significant association between parathyroid hormone and uric acid level in men.
            (Chin et al., 2015) Download
BACKGROUND:  Previous reports of patients undergoing parathyroidectomy and of patients receiving teriparatide as antiosteoporotic treatment have suggested a plausible relationship between parathyroid hormone (PTH) and uric acid. However, similar data at population level were lacking. The current study aimed to determine the relationship between PTH and uric acid in a group of apparently healthy Malaysian men. METHODS:  A cross-sectional study was conducted among 380 Malay and Chinese men aged 20 years and above, residing in the Klang Valley, Malaysia. Their body anthropometry was measured, and their fasting blood samples were collected for biochemical analysis. The relationship between PTH and uric acid was analyzed using regression analysis. RESULTS:  Increased serum PTH level was significantly associated with increased serum uric acid level (β=0.165; P=0.001). Increased PTH level was also significantly associated with the condition of hyperuricemia in the study population (odds ratio [OR], 1.045; 95% confidence interval [CI], 1.017-1.075; P=0.002). All analyses were adjusted for age, body mass index, vitamin D, total calcium, inorganic phosphate, blood urea nitrogen and creatinine levels. CONCLUSION:  There is a significant positive relationship between PTH level and uric acid level in Malaysian men. This relationship and its clinical significance should be further investigated in a larger longitudinal study.

Vitamin B6 status and interferon-γ-mediated immune activation in primary hyperparathyroidism.
            (Christensen et al., 2012) Download
OBJECTIVES:  Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and elevated risk of cardiovascular disease (CVD). In inflammatory conditions, interferon-γ (IFN-γ) activity is enhanced and a decreased circulating concentration of vitamin B6 is often observed. Such changes in IFN-γ activity or vitamin B6 levels have been associated with increased incidence of CVD. The aim of the study was to investigate systemic markers of IFN-γ-mediated immune activation, such as neopterin, the kynurenine-to-tryptophan ratio (KTR) and kynurenine pathway metabolites, as well as B6 vitamers in patients with PHPT. DESIGN/SUBJECTS:  A total of 57 patients with PHPT and a control group of 20 healthy blood donors were included in this study. PHPT patients who responded positively to parathyroidectomy were followed for 6 months. Forty-three patients participated in the longitudinal study in which blood samples were taken at inclusion and 1, 3 and 6 months after surgery. RESULTS:  Plasma concentrations of the B6 vitamers pyridoxal 5'-phosphate (PLP) (P = 0.007) and pyridoxal (P = 0.013) were significantly lower in the patient group compared to healthy control subjects. An increase in the KTR indicated that the kynurenine pathway of tryptophan metabolism was altered in PHPT patients (P = 0.015). During the initial 6 months after surgery, levels of PLP (P < 0.001) and anthranilic acid (P < 0.001) increased significantly, whereas neopterin decreased (P = 0.018). CONCLUSIONS:  The results of this study demonstrate altered levels of vitamin B6 and the KTR in PHPT patients, both of which may reflect cellular immune activation. These abnormalities should be considered in relation to the increased risk of CVD previously observed in patients with PHPT.

Novel inflammatory biomarkers in primary hyperparathyroidism.
            (Christensen et al., 2015) Download
OBJECTIVE:  Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and increased risk of cardiovascular disease (CVD). The aim of the study was to investigate systemic levels of pro-inflammatory proteins that previously have not been examined in patients with PHPT. The selection of the pro-inflammatory biomarkers included in this study, MMP9, S100A4, S100A8/A9 and the receptors sCD14 and RAGE, was based on a previous microarray screen of mRNAs in adipose tissue from PHPT patients. DESIGN:  A prospective study was conducted on a total of 57 patients with PHPT and a control group of 20 healthy blood donors. METHODS:  PHPT patients with normalisation of serum calcium levels after parathyroidectomy were followed for 6 months. Forty-two patients participated in the longitudinal study, in which blood samples were taken at inclusion, and 1, 3 and 6 months after surgery. RESULTS:  We observed increased serum levels of MMP9 (P=0.029), S100A4 (P<0.001) and sCD14 (P=0.002) in the 57 patients with PHPT compared to the control-group. During 6 months of follow up, S100A4 (P=0.022) and sCD14 (0.002) decreased significantly, while serum levels of MMP9 increased (P=0.025). CONCLUSIONS:  The results demonstrate an increased inflammatory response in PHPT patients shown by elevated MMP9, S100A4 and sCD14 at inclusion. During the 6 months of follow-up, MMP9 increased further, possibly due to the tissue repair process after parathyroidectomy. S100A4 and sCD14 decreased after surgery demonstrating a partial reversal of the systemic inflammation.

Circulating leptin and adiponectin levels in patients with primary hyperparathyroidism.
            (Delfini et al., 2007) Download
Primary hyperparathyroidism (PHPT) has been associated with high cardiovascular morbidity and mortality; its pathogenesis is not fully understood. Moreover, many metabolic abnormalities are frequently present in patients with PHPT. Several substances (such as leptin and adiponectin) are secreted from adipocytes, which may contribute to regulate energy homeostasis and the development of cardiovascular diseases. We examined the relationship between leptin and adiponectin levels and metabolic disorders in 67 newly diagnosed never-treated patients with PHPT and in 46 healthy subjects (HS). Twenty (29.8%) patients with PHPT presented a metabolic syndrome (as defined by Adult Treatment Panel III criteria). Serum leptin and adiponectin levels in HS were 6.28 +/- 3.3 ng/mL (range, 1.7-19.2 ng/mL) and 6.65 +/- 1.7 microg/mL (range, 3.72-10.86 microg/mL), respectively. In all patients with PHPT, the mean leptin levels (34.28 +/- 20.4 ng/mL) were significantly higher than those of HS (P < .01) and, in particular, in PHPT patients with metabolic syndrome (52.63 +/- 31.2 ng/mL) and positively correlated with body mass index, waist circumference, and cholesterol. The mean adiponectin level was significantly lower (4.34 +/- 3.5 mug/mL) only in PHPT patients with metabolic syndrome (P < .005) and negatively correlated with waist circumference and fasting glucose. We concluded that increased serum level of leptin and decreased serum level of adiponectin coexist in patients with PHPT and may represent a pathogenetic factor for cardiovascular disease in this condition.

Oxidative stress and angiogenesis in primary hyperparathyroidism.
            (Deska et al., 2017) Download
BACKGROUND:  The inappropriate elevation of parathormone (PTH), which regulates the process of angiogenesis in parathyroid tissue, causes the changes of activity of enzymes responsible for the removal of free radicals. Parathyroidectomy (PTX) in patients with primary hyperparathyroidism (PHPT) lowers the level of PTH and leads to the reduction of risk of cardiovascular and all-cause mortality by normalization of the antioxidant status. Therefore, the aims of the study were to assess the activity of antioxidant enzymes and free radical reaction products in patients after parathyroidectomy, and to evaluate the correlation between the systemic oxidative stress and angiogenic parameters. MATERIALS AND METHODS:  Patients with PHPT treated surgically were enrolled into the study. Total antioxidant capacity (TAC), total oxidative status (TOS), oxidative stress index (OSI), superoxide dismutase (SOD), ceruloplasmin (CER), lipid hydroperoxides (LHP) and malondialdehyde (MDA) were measured before and after parathyroidectomy. The immunohistological expression of angiogenic factors in parathyroid specimens was assessed by the BrightVision method from ImmunoLogic using murine monoclonal anti-human: anti-VEGF, anti-CD31 and anti-CD106 antibodies. RESULTS:  The significant increase of TAC, CER, reduction of TOS, MDA, SOD, especially for cytoplasmic form, and significant decrease of OSI, LHP were observed after PTX. There was no significant correlation between changes of oxidative stress markers and angiogenic parameters: VEGF, CD-31, CD-106 in parathyroid tissue. The correlation level was low and medium. CONCLUSIONS:  Parathyroidectomy causes down-regulation of lipid peroxidation processes and leads to reduction of oxidative stress in patients with PHPT. The decrease in the OSI is the results of down-regulation of oxidative stress in the postoperative period. The change of the antioxidant status has no impact on angiogenesis processes in parathyroid tissue.

Parathyroidectomy Decreases Insulin Resistance Index in Patients with Primary Hyperparathyroidism.
            (Duran et al., 2017) Download
Primary hyperparathyroidism (PHPT) has been considered a cause of insulin resistance (IR) and impaired glucose metabolism. However, there are conflicting results related with the recovery of insulin resistance in patients with PHPT following curative parathyroidectomy. Our aim is to evaluate the effects of curative parathyroidectomy on IR in patients with PHPT. This is a prospective interventional study. Twenty-one consecutive patients with symptomatic PHPT were included into the study. All patients underwent parathyroidectomy. Fasting serum glucose, calcium, phosphorous, parathormone, plasma insulin, and vitamin D levels were measured both at baseline and 2 months after parathyroidectomy. Insulin resistance was calculated by homeostasis of model assessment-insulin resistance (HOMA-IR). Two months after curative parathyroidectomy, serum levels of calcium (p = 0.001), PTH (p < 0.001), insulin (p = 0.003), and HOMA-IR (p = 0.003) decreased, while phosphorous levels increased (p = 0.001). During this period, no changes were observed at vitamin D and glucose levels. We concluded that curative parathyroidectomy decreases HOMA-IR index in patients with PHPT. Studies with larger population and longer follow-up period are required to confirm our results.

Blood coagulation, fibrinolysis and lipid profile in patients with primary hyperparathyroidism: increased plasma factor VII and X activities and D-Dimer levels.
            (Erem et al., 2008) Download
BACKGROUND AND OBJECTIVES:  Primary hyperparathyroidism (PHPT) is associated with an increased cardiovascular mortality and morbidity rate. However, the exact role of PTH and/or calcium in the development of cardiovascular disease (CVD) is still controversial. The influence of PHPT on hemostasis is yet unknown. Therefore, the main purpose of this study was to investigate the markers of endogenous coagulation/fibrinolysis and to evaluate the relationships between these hemostatic parameters, serum lipid profile and serum calcium and PTH in patients with PHPT. DESIGN AND METHODS:  Twenty-three patients with PHPT and 20 age-matched healthy controls were included in the study. Fibrinogen, factors V, VII, VIII, IX and X activities, von Willebrand factor (vWF), antithrombin III (AT III), protein C, protein S, tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor-1 (PAI-1), as well as common lipoprotein variables, were measured. The relationships between biochemical parameters and these hemostatic parameters were examinated. RESULTS:  Compared with the control subjects, platelet count, FVII, FX activities, and D-Dimer levels were significantly increased in patients with PHPT (p<0.001, p<0.05, p<0.001, and p<0.05, respectively). Among the lipids, the levels of TC, TG and LDL-C were significantly increased in patients with PHPT (p<0.01, p<0.001, p<0.001, respectively) than those in controls. In patients with PHPT, we showed a positive correlation between urinary phosphorus excretion and factors VIII, IX, and X (r: 0.572, p<0.01; r: 0.543, p<0.01; r: 0.532, p<0.01, respectively). F IX activity was positively correlated with TC (r: 0.463, p<0.05) and LDL-C (r: 0.549, p<0.01) There was a positive correlation between serum ALP and PAI-1 levels (r: 0.451, p<0.05). ApoB was positively correlated with D-Dimer (r: 0.421, p<0.05). We did not find any significant correlation between iPTH and serum calcium and the hemostatic parameters that we measured. INTERPRETATION AND CONCLUSIONS:  In conclusion, we found some important differences in the hemostatic parameters between the patients with PHPT and healthy controls. Increased platelet count, F VII and FX activities and D-Dimer levels in patients with PHPT represent a potential hypercoagulable state, which might augment the risk for atherosclerotic and atherothrombotic complications. This condition may contribute to the excess mortality rate due to CVD in patients with PHPT.

The independent association between parathyroid hormone levels and hyperuricemia: a national population study.
            (Hui et al., 2012) Download
INTRODUCTION:  Increased frequencies of hyperuricemia and gout have been associated with primary hyperparathyroidism, and recent clinical trials of parathyroid hormone (PTH) have reported hyperuricemic adverse events. We evaluated the potential population impact of PTH on serum uric acid (SUA) levels by using a nationally representative sample of United States adults. METHODS:  By using data from 8,316 participants aged 18 years and older in the National Health and Nutrition Examination Survey 2003 to 2006, we examined the relation between serum PTH and SUA levels with weighted linear regression. Additionally, we examined the relation with hyperuricemia by using weighted logistic regression. RESULTS:  SUA levels increased with increasing serum PTH concentration. After adjusting for age, sex, dietary factors, glomerular filtration rate (GFR), and other potentially related biomarkers (calcium, phosphorus, alkaline-phosphatase, 25-hydroxyvitamin D), the SUA level differences from the bottom (referent) to top quintiles of serum PTH levels were 0, 8, 13, 14, and 19 μM (95% CI, 12 to 26; P for trend, < 0.001). These estimates were larger among renally impaired individuals (multivariate SUA difference between the extreme quintiles of PTH, 26 versus 15 μM among those with GFR ≥ 60 versus < 60 ml/min per 1.73 m2, respectively) (P for interaction = 0.004). The odds of hyperuricemia by various definitions increased with increasing PTH levels as well (multivariate P values for trend, < 0.05). CONCLUSIONS:  These nationally representative data indicate that serum PTH levels are independently associated with serum uric acid levels and the frequency of hyperuricemia at the population level.

Is there a link between Hashimoto's thyroiditis and primary hyperparathyroidism? A study of serum parathormone and anti-TPO antibodies in 2267 patients.
            (Ignjatovic et al., 2013) Download
According to various authors, thyroid disorders like Hashimoto's thyroiditis (HT), diffuse goiter or multinodular goiter, Graves' disease, medullary or papillary carcinoma could be found in a number of patients with primary hyperparathyroidism (PHPT). This association is more common in elderly women. Neck irradiation, lithium treatment and elevated TSH levels have been suggested as some of the possible causes of this co-existance. The aim of this study was to investigate and determine the prevalence of patients having both HT and PHPT, and the possible relation between these two diseases. We conducted a prospective study during three and a half years. This study included 45,231 patients, which were referred by their general practitioner or endocrinologist, under suspicion of having thyroid and/or parathyroid disease. In these patients we measured serum levels of the following parameters: anti-thyroid peroxidase antibodies (antiTPO-Ab), anti-thyroglobulin antibodies (Tg-Ab), anti-TSH-receptor antibodies (TSHR-Ab), thyroid-stimulating hormone (TSH), parathyroid hormone (PTH) and calcium (Ca). In 2,267 of these 45,231 patients (5.01%) we noticed elevated antiTPO-Ab (3542±3407IU/mL), with statistical significant difference from normal values (normal range 0-70IU/mL), P<0.05, and normal levels of other antithyroid antibodies (Tg-Ab, TSHR-Ab). All patients with elevated antiTPO-Ab were assumed to have HT. Within this group, 43 patients (1.89%) also had elevated serum levels of PTH (112.4±33.2pg/mL, normal range 8-76pg/mL) as well as elevated serum levels of calcium (2.92±0.06mmol/L, normal range 2.2-2.65mmol/L). These laboratory findings, accompanied with clinical symptoms, satisfied the criteria for PHPT. The mean age in this subgroup was 60.5±12.2 years. All 2,267 patients had normal or slightly elevated TSH levels. In conclusion, although the reported rate of prevalence of PHPT in the general population is about 0.3%, our results indicated a 1.89% occurrence of PHPT in 2267 patients with HT in central Serbia. This may be due to the autoimmune inflammatory process in HT supporting PHPT to PTH or calcium supporting HT or to common genetical predisposition of both entities.

Tradeoff-in-the-Nephron: A Theory to Explain the Primacy of Phosphate in the Pathogenesis of Secondary Hyperparathyroidism.
            (Phelps, 2017) Download
Chronic kidney disease (CKD) causes secondary hyperparathyroidism (SHPT). The cardinal features of SHPT are persistence of normocalcemia as CKD progresses and dependence of the parathyroid hormone concentration ([PTH]) on phosphate influx (IP). The tradeoff-in-the-nephron hypothesis integrates these features. It states that as the glomerular filtration rate (GFR) falls, the phosphate concentration ([P]CDN) rises in the cortical distal nephron, the calcium concentration ([Ca]CDN) in that segment falls, and [PTH] rises to maintain normal calcium reabsorption per volume of filtrate (TRCa/GFR). In a clinical study, we set GFR equal to creatinine clearance (Ccr) and IP equal to the urinary excretion rate of phosphorus (EP). We employed EP/Ccr as a surrogate for [P]CDN. We showed that TRCa/Ccr was high in patients with primary hyperparathyroidism (PHPT) and normal in those with SHPT despite comparably increased [PTH] in each group. In subjects with SHPT, we examined regressions of [PTH] on EP/Ccr before and after treatment with sevelamer carbonate or a placebo. All regressions were significant, and ∆[PTH] correlated with ∆EP/Ccr in each treatment cohort. We concluded that [P]CDN determines [PTH] in CKD. This inference explains the cardinal features of SHPT, much of the evidence on which other pathogenic theories are based, and many ancillary observations.

The oral glucose tolerance test reveals a high frequency of both impaired glucose tolerance and undiagnosed Type 2 diabetes mellitus in primary hyperparathyroidism.
            (Procopio et al., 2002) Download
AIMS:  To evaluate the frequency of impaired glucose tolerance (IGT)and undiagnosed diabetes mellitus together with the indices of insulin resistance (IR) in primary hyperparathyroidism (pHPT). METHODS:  Out of 105 consecutive pHPT patients (F/M 78/27, asymptomatic/symptomatic 68/37, age (mean +/- s.d.) 60.7 +/- 12.7 years,body mass index 25.2 +/- 3.8 kg/m2, ionized calcium (iCa) 1.49 +/- 0.16 mmol/l,parathormone 200.4 +/- 233.9 pg/ml),59 without known diabetes mellitus and controls (n = 60) underwent an oral glucose tolerance test (OGTT, 75 g os). As indices of IR, homeostasis model assessment (HOMAIR)or OGTT data (insulin sensitivity index composite (ISI comp)) were evaluated. RESULTS:  In pHPT the prevalence of IGT (mean, 95% confidence intervals (CI), 40.7%, 27.8-53.6) was higher than in controls (25.0%, 13.7-36.3, P < 0.03). Similarly,the prevalence of undiagnosed diabetes mellitus was higher in pHPT(15.3%, 5.8-24.7) than in controls (5.0%, 0-10.7, P < 0.05). Moreover,the prevalence of IGT and undiagnosed diabetes was higher in pHPT than that previously reported in the general population of Northern Italy(8.5% and 3.2%, respectively). The indices showed that insulin resistance was higher in pHPT than in controls: HOMAIR (median, 95% CI,2.6, 2.5-3.9 vs. 1.7, 1.6-2.5, respectively; P < 0.003); ISI comp (3.5, 3.4-4.6 vs. 5.1, 4.9-7.2, respectively; P < 0.002). CONCLUSIONS:  Our data in a large and modern day pHPT series, with a preponderance of asymptomatic patients, confirm increased insulin resistance and pre-valence of IGT and undiagnosed diabetes.

The Relation of the Dietary CA:P Ratio to Serum CA and to Parathyroid Volume: Three Figures
            (Stoerk and Carnes, 1945) Download
A close direct proportionality has been found between the logarithm of the dietary Ca/P ratio and the serum Ca concentration in mature rats on an adequate basal ration over a very wide range of dietary Ca and P. A similarly close inverse proportionality has been found between the logarithm of the dietary Ca/P ratio and the volume of the para thyroid glands. The parathyroid volume and serum Ca concentration accordingly varied inversely and with a nearly linear relationship be tween serum Ca levels of 7.3 and 11.9 mg. %. The serum inorganic P04 level was less uniformly related to the parathyroid size under the present experimental conditions.

Coincident diabetes mellitus and primary hyperparathyroidism.
            (Taylor and Khaleeli, 2001) Download
The prevalence of diabetes mellitus in primary hyperparathyroidism is approximately 8% and that of primary hyperparathyroidism in diabetic patients is approximately 1%. Both values are about three-fold higher than the respective expected prevalences in general populations. Patients with both disorders are over 40 years of age and 80% are female; 22% have type 1 and 78% type 2 diabetes. Primary hyperparathyroidism presents first in approximately 20% of patients, and diabetes mellitus in 40%; both disorders present together, or within 1 year, in 40%. Approximately 40% of patients with primary hyperparathyroidism have impaired glucose tolerance. Insulin resistance is present in hyperparathyroidism and probably arises from a raised intracellular free calcium concentration which, by decreasing normal insulin-stimulated glucose transport, increases the requirement for insulin: if this insulin resistance progresses, impaired glucose tolerance and diabetes mellitus would result. Parathyroidectomy has been followed by regression of diabetes and of impaired glucose tolerance in some but not all patients. Early diagnosis of the second disorder is clinically desirable when one disorder is present. Hyperparathyroid patients should therefore be screened for impaired glucose tolerance and diabetes annually, and pre-operatively. Diabetic patients should be checked for hypercalcaemia at appropriate intervals; although only 1% of them may have hyperparathyroidism, this disorder if untreated is associated with hypertension, to which diabetic patients are already prone.

Homoarginine in patients with primary hyperparathyroidism.
            (Tomaschitz et al., 2015) Download
BACKGROUND:  Low levels of the amino acid homoarginine and parathyroid hormone (PTH) excess are both independently related to an increased risk of cardiovascular morbidity and mortality. Accumulating evidence points to a mutual interplay between homoarginine and PTH. The authors therefore aimed to investigate circulating homoarginine levels in patients with and without primary hyperparathyroidism (PHPT). METHODS:  The authors performed a cross-sectional analysis of serum homoarginine levels in 59 patients with mild and severe PHPT and in 92 control persons matched for age, sex and estimated glomerular filtration rate. RESULTS:  Median PTH and serum homoarginine concentrations were 99.1 (79.7-120.2) pg/mL and 1.16 (0.95-1.66) µmol/L in patients with PHPT (79.7% female; 42.4% with normocalcemia) as compared with 45.8 (36.4-53.9) pg/mL and 1.62 (1.33-2.04) µmol/L in the control group (P < 0.001 for both), respectively. The authors observed no statistically differences between cases and controls for 25-hydroxyvitamin D [25(OH)D], serum albumin, hemoglobin, waist-to-hip ratio, C-reactive protein and NT-pBNP values. Multivariate analysis of covariance revealed that patients with PHPT had significantly lower homoarginine levels than controls (P < 0.001). This difference remained significant after adjusting for multiple confounders such as 25(OH)D, body mass index, LDL cholesterol, albumin, calcium, hemoglobin, smoking status and current antihypertensive medication. The differences of homoarginine levels persisted even after exclusion of patients with estimated glomerular filtration rate <60 mL/min (P = 0.003) and 25(OH)D levels <30 ng/mL (P = 0.001), respectively. CONCLUSIONS:  Patients with PHPT have lower homoarginine levels compared with matched controls irrespective of age, sex, kidney function and 25(OH)D status. Further studies are needed to evaluate whether low homoarginine accounts for higher cardiovascular risk conferred by PTH excess.

Low-grade inflammation and tryptophan-kynurenine pathway activation are associated with adverse cardiac remodeling in primary hyperparathyroidism: the EPATH trial.
            (Verheyen et al., 2017) Download
BACKGROUND:  Primary hyperparathyroidism (pHPT) is associated with low-grade inflammation, left ventricular hypertrophy and increased cardiovascular mortality, but the association between inflammatory markers and parameters of adverse cardiac remodeling is unknown. We investigated the relationship between C-reactive protein (CRP), the essential amino acid tryptophan and its pro-inflammatory derivatives kynurenine and quinolinic acid (QUIN) with echocardiographic parameters. METHODS:  Cross-sectional baseline data from the "Eplerenone in Primary Hyperparathyroidism" trial were analyzed. Patients with any acute illness were excluded. We assessed associations between CRP, serum levels of tryptophan, kynurenine and QUIN and left ventricular mass index (LVMI), left atrial volume index (LAVI) and E/e'. RESULTS:  Among 136 subjects with pHPT (79% females), 100 (73%) had arterial hypertension and the prevalence of left ventricular hypertrophy was 52%. Multivariate linear regression analyses with LVMI, LAVI and E/e' as respective dependent variables, and C-reactive protein and tryptophan, kynurenine and QUIN as respective independent variables were performed. Analyses were adjusted for age, sex, blood pressure, parathyroid hormone, calcium and other cardiovascular risk factors. LVMI was independently associated with CRP (adjusted β-coefficient=0.193, p=0.030) and QUIN (β=0.270, p=0.007), but not kynurenine. LAVI was related with CRP (β=0.315, p<0.001), kynurenine (β=0.256, p=0.005) and QUIN (β=0.213, p=0.044). E/e' was related with kynurenine (β=0.221, p=0.022) and QUIN (β=0.292, p=0.006). Tryptophan was not associated with any of the remodeling parameters. [Correction added after online publication (22 April 2017: The sentence "Among 136 subjects with pHPT (79% females), 100 (73%) had left ventricular hypertrophy." was corrected to "Among 136 subjects with pHPT (79% females), 100 (73%) had arterial hypertension and the prevalence of left ventricular hypertrophy was 52%."] Conclusions: Cardiac remodeling is common in pHPT and is associated with low-grade inflammation and activation of the tryptophan-kynurenine pathway. The potential role of kynurenine and QUIN as cardiovascular risk factors may be further investigated in future studies.

Phosphate administration increases both size and number of parathyroid cells in adult rats.
            (Wang et al., 1996) Download
Phosphate administration increases both parathyroid hormone (PTH) secretion and parathyroid size in rats, but the relative contribution of hypertrophy and hyperplasia is unknown. Accordingly, we reexamined parathyroid histology in a previously published experiment [6], quantitatively rather than qualitatively. Ninety female Long-Evans rats were divided into six groups; three were given a normal diet, and three a high phosphate diet (Ca/P 1:7). One group from each arm was killed after 1, 2, and 3 months. Quantitative microscopy was performed on the parathyroid section with the largest area from each animal, without knowledge of its experimental status. Total gland area and total number of cell profiles did not change significantly in the control rats, but increased progressively in the phosphate-loaded rats. At 3 months, the difference was +194% for gland area and+151% for profile number (P < 0.0001), much more than could be accounted for by suppression of apoptosis. Mean nuclear profile area and mean cell profile area (including associated connective tissue as well as cytoplasm) were both significantly increased at 1 month (P < 0.0001). The differences persisted, but their magnitudes (about +16%) did not change further. This time course was consistent with the morphologic expression of increased PTH secretory activity. We conclude that phosphate administration to adult rats increases both size and number of parathyroid cells, the latter due to increased cell proliferation. Phosphate-stimulated parathyroid growth could be due to either hypocalcemia or decreased calcitriol production; increased cell division may also be linked to increased hormone secretion, regardless of its cause. The relative importance of these different mechanisms remains to be determined.

Parathyroidectomy, elevated depression scores, and suicidal ideation in patients with primary hyperparathyroidism: results of a prospective multicenter study.
            (Weber et al., 2013) Download
OBJECTIVE:  To assess anxiety and depression symptoms, suicidal ideation, and health-related quality of life (HRQOL) in a large series of consecutive patients with primary hyperparathyroidism (pHPT) before and after parathyroidectomy. DESIGN:  This prospective multicenter study investigated preoperative and postoperative depression, anxiety, suicidal ideation, and HRQOL in patients with pHPT and compared these variables with a control group with nontoxic thyroid nodules. PATIENTS:  The study included 194 patients with pHPT and 186 control subjects. MAIN OUTCOME MEASURES:  Depression was evaluated with the Hospital Anxiety and Depression Scale (HADS) and the Patient Health Questionnaire-9, which also assessed suicidal ideation. Anxiety was evaluated with the HADS. Health-related quality of life was measured with the 36-Item Short Form survey. RESULTS:  Parathyroidectomy achieved a 98% cure rate. Preoperatively, severe depression (HADS score ≥ 11) was seen in 20% of the pHPT group and 9% of the control group. The Patient Health Questionnaire-9 detected moderate to severe depression in 17% of the patients with pHPT and 7% of the control subjects. Patients with pHPT had higher HADS anxiety scores (mean, 7.7) than control subjects (P < .01) or the German normative sample (P < .001). Compared with control subjects, patients with pHPT had significantly lower 36-Item Short Form survey preoperative physical and mental health summary scores (42.7 vs 49.5 and 41.2 vs 46.8, respectively; P = .001 for both comparisons). At 12 months follow-up, depression and anxiety decreased significantly in patients with pHPT; the prevalence of suicidal ideation was more than halved from the baseline (10.7% vs 22%; P = .008). Both physical and mental health scores (45.7 and 47.7, respectively) improved in patients with pHPT (P < .001 each) but not in control subjects. CONCLUSIONS:  Depression, anxiety, and decreased HRQOL appear to be related to pHPT. Successful parathyroidectomy seems to reduce psychopathologic symptoms and improve HRQOL in this setting.

Primary hyperparathyroidism, insulin resistance, and cardiovascular disease: a review.
            (Ybarra et al., 2007) Download
The presentation of primary hyperthyroidism (PHPT) has changed substantially in the last decade. Before the introduction of routine calcium measurement in most automated biochemistry serum analyzers, it usually was diagnosed after renal and bony lesions already were present. Nowadays, its presentation is practically asymptomatic. Nevertheless, the cardiovascular morbidity and mortality of mild to moderate forms of PHPT reportedly are increasing. Individuals who have mild to moderate forms of PHPT have an increased risk for enduring cardiovascular disease, arterial hypertension, left ventricular hypertrophy, myocardial and valvular calcifications, altered vascular reactivity, and cardiac conduction. Finally, they also reveal alterations in carbohydrate metabolism, insulin resistance, dyslipidemia, and body composition.

 


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