Parathyroid hormone induces hepatic production of bioactive interleukin-6 and its soluble receptor

Parathyroidectomy Reduces Inflammatory Cytokines and Increases Vitamin D Metabolites in Patients With Primary Hyperparathyroidism

OBJECTIVE

Primary hyperparathyroidism (PHPT) is accompanied by a decreased 25-hydroxyvitamin D (25OHD) and vitamin D binding protein (DBP). High parathyroid hormone (PTH) is associated with elevated interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), yet the effect of parathyroidectomy (PTX) on DBP and cytokines is not clear. This study aims to prospectively evaluate the effect of PTX on inflammatory profiles, total and free 25OHD, and DBP in patients with PHPT.

METHODS

Newly diagnosed patients with PHPT were recruited for the study (n = 70). Twenty-eight patients returned after PTX, 3 months later. Biochemical markers were measured before and after PTX. A group of age and body mass index-matched healthy subjects were included as controls (n = 70).

RESULTS

Before PTX, patients had lower serum DBP (37.5 ± 6.0 vs 41.5 ± 6.1 mg/dL, P < .001) and total 25OHD (30.1 ± 9.5 vs 33.3 ± 7.9 ng/mL, P < .05) but similar free 25OHD when compared to controls. Serum IL-6, C-reactive protein, and MCP-1 were higher in patients with PHPT (P < .05), whereas interleukin-10 was similar to that in controls. PTX increased total and free 25OHD and DBP (P < .001) and decreased serum IL-6 and MCP-1 (P < .05), but not C-reactive protein and interleukin-10. Multiple regression analysis indicated that the preoperative PTH explained a significant portion of the variance of IL-6 and MCP-1 (P < .05).

CONCLUSION

These findings suggest that PTH may upregulate the production of MCP-1 and IL-6 and downregulate circulating DBP in patients with PHPT that are normalized by PTX. The exact mechanism of IL-6 and MCP-1 on DBP, vitamin D metabolites, and clinical outcomes in patients with PHPT is an area requiring further study.

The calcium-clot connection: investigating the association between primary hyperparathyroidism and acute venous thromboembolism

Primary hyperthyroidism (PHPT) is a relatively uncommon disease and leads to increased calcium levels. Ionized calcium, known as clotting Factor IV, may lead to overt coagulation cascade activation, increasing the risk of venous thromboembolism (VTE). National Inpatient Sample Database was used to sample individuals with primary hyperparathyroidism, and baseline demographics and comorbidities were collected using ICD-10 codes. Patients with missing data and age less than 18 were excluded. Moreover, patients with other types of hyperparathyroidism and risk factors for VTE, such as malignancy, thrombophilia, chronic kidney and liver disease, fractures, trauma, oral contraceptive/steroid use, and organ transplant, were excluded. Greedy propensity matching using R was performed to match patients with and without primary hyperparathyroidism on age, race, gender, and 10 other comorbidities, including chronic deep venous thromboembolism. Univariate analysis pre- and post-match were performed. Binary logistic regression was performed after matching to assess whether primary hyperparathyroidism was an independent risk factor for acute VTE. A p-value of  < 0.05 was considered statistically significant. Out of 460,529 patients included in the study, 1114 (6.5%) had PHPT. Baseline comorbidities were more common in the PHPT group. On univariate analysis, patients with PHPT were more likely to have acute VTE (2.5% vs. 1.4%; p < 0.001). After 1:1 matching, PHPT patients were twice as likely to have Acute VTE. (OR: 2.1 [1.08-4.1]; p < 0.025). These findings suggest an association between PHPT and VTE, which should be further investigated to prevent the increasing incidence of VTE and its recurrence.

Parathyroidectomy Improves the Consumption of Erythropoiesis-Stimulating Agents in Hemodialysis Patients

Secondary hyperparathyroidism (SHPT) is common in end-stage renal disease (ESRD) patients, and it can suppress erythropoiesis. We aimed to investigate the relationship between the consumption of erythropoiesis-stimulating agents (ESAs) and parathyroidectomy (PTX) in ESRD patients with SHPT and to determine the predictors for anemia improvement. The current standard of chronic kidney disease anemia therapy relies on the prescription of iron supplementation, and ESA. We retrospectively analyzed 81 ESRD patients with PTX at Ditmanson Medical Foundation Chiayi Christian Hospital from July 2004 to Dec 2018. The requirement of ESA therapy markedly declined from a dose of 41.6 (interquartile range [IQR], 0−91.2) to 10.3 (IQR, 0−59.5, p = 0.001) unit/kg/week. In addition, 63.7% of patients required iron replacement therapy preoperatively and the proportion reduced to 52.5% after PTX (p < 0.001). The hemoglobin (Hb) level showed an insignificant change from a median value of 10.7 g/dL (9.5−11.6 g/dL) before PTX to 10.5 g/dL (9.6−11.2 g/dL) at 6 months after PTX. A preoperative Hb level ≤ 10 mg/dL (odds ratio [OR], 20.1; 95% confidence interval [CI], 4.71−125, p < 0.001) and transferrin saturation (TSAT) < 25% (OR, 12.8; 95% CI, 2.51−129, p < 0.001) were predictors for anemia improvement. Our study demonstrated that PTX markedly decreased the requirement of ESA. Patients with a low preoperative Hb level or low TSAT showed an increase in the Hb level after PTX. PTX may be considered not only for SHPT with refractory anemia but also for high ESA-dependent patients.

Alterations in circulating levels of vitamin D binding protein, total and bioavailability of vitamin D in diabetic retinopathy patients

AIMS

This study aimed to investigate the association between circulating levels of vitamin D binding protein (VDBP) and its genotypes and diabetic retinopathy risk.

METHODS

This case-control study recruited 154 patients with type 2 diabetes mellitus; 62 with diabetic retinopathy (DR) and 92 without DR and diabetic nephropathy (DN). Circulating levels of 25-hydroxyvitamin D3 and VDBP levels were measured in the patients. The genotype and phenotype of VDBP were evaluated based on two common VDBP variations; rs7041 and rs4588.

RESULTS

Serum levels of VDBP were significantly lower in patients with DR than in patients without DR and/or DN (Ln-VDBP (μg/ml): 6.14 ± 0.92 vs. 6.73 ± 1.45, p = 0.001) even after adjustment for age, sex, body mass index, disease duration, estimated glomerular filtration rate (eGFR), HbA1C, insulin therapy profile, and serum levels of 25(OH)D. The distribution of VDBP phenotypes and genotypes in the two studied groups were nearly the same, and the distribution was similar to that of the general population.

CONCLUSIONS

In this study, we found the association between lower circulating levels of VDBP and risk of DR. However, the precise mechanism linking these two remains unknown. Further and more in-depth research is needed to find out the underlying causes of the relationship.

Effect of Parathyroidectomy on Metabolic Homeostasis in Primary Hyperparathyroidism

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

Parathyroid hormone levels and aging: Effect on balance

Falls result in multiple adverse health outcomes including mortality in older persons. Impaired balance is known to increase the risk of falls. Numerous factors play a role in the etiology of balance disturbance. Among the calciotropic hormones, the role of vitamin D in falls risk has been extensively studied. There is evolving interest in the role of parathyroid hormone (PTH) in this area. Elevated PTH hormone levels have been associated with age-related syndromes such as frailty, osteoporosis, and sarcopenia. Among the existing studies, most have focused on muscle strength with few studies evaluating its role in balance disturbances. In this chapter, we will summarize the aspects of PTH and aging, its biological effects on muscle, and the known associations between PTH and balance.

Inactivation of parathyroid hormone: perspectives of drug discovery to combating hyperparathyroidism

Hormonal coordination is tightly regulated within the human body and thus regulates human physiology. The parathyroid hormone (PTH), a member of the endocrine system, regulates the calcium and phosphate level within the human body. Under non-physiological conditions, PTH levels get upregulated (hyperparathyroidism) or downregulated (hypoparathyroidism) due to external or internal factors. In the case of hyperparathyroidism, elevated PTH stimulates cellular receptors present in the bones, kidneys, and intestines to increase the blood calcium level, leading to calcium deposition. This eventually causes various symptoms including kidney stones. Currently, there is no known medication that directly targets PTH in order to suppress its function. Therefore, it is of great interest to find novel small molecules or any other means that can modulate PTH function. The molecular signaling of PTH starts by binding of its N-terminus to the G-protein coupled PTH1/2 receptor. Therefore, any intervention that affects the N-terminus of PTH could be a lead candidate for treating hyperparathyroidism. As a proof-of-concept, there are various possibilities to inhibit molecular PTH function by (i) a small molecule, (ii) N-terminal PTH phosphorylation, (iii) fibril formation and (iv) residue-specific mutations. These modifications put PTH into an inactive state, which will be discussed in detail in this review article. We anticipate that exploring small molecules or other means that affect the N-terminus of PTH could be lead candidates in combating hyperparathyroidism.

Impact of 3D cell culture on bone regeneration potential of mesenchymal stromal cells

As populations age across the world, osteoporosis and osteoporosis-related fractures are becoming the most prevalent degenerative bone diseases. More than 75 million patients suffer from osteoporosis in the USA, the EU and Japan. Furthermore, it is anticipated that the number of patients affected by osteoporosis will increase by a third by 2050. Although conventional therapies including bisphosphonates, calcitonin and oestrogen-like drugs can be used to treat degenerative diseases of the bone, they are often associated with serious side effects including the development of oesophageal cancer, ocular inflammation, severe musculoskeletal pain and osteonecrosis of the jaw.The use of autologous mesenchymal stromal cells/mesenchymal stem cells (MSCs) is a possible alternative therapeutic approach to tackle osteoporosis while overcoming the limitations of traditional treatment options. However, osteoporosis can cause a decrease in the numbers of MSCs, induce their senescence and lower their osteogenic differentiation potential.Three-dimensional (3D) cell culture is an emerging technology that allows a more physiological expansion and differentiation of stem cells compared to cultivation on conventional flat systems.This review will discuss current understanding of the effects of different 3D cell culture systems on proliferation, viability and osteogenic differentiation, as well as on the immunomodulatory and anti-inflammatory potential of MSCs.

Race-specific associations of 25-hydroxyvitamin D and parathyroid hormone with cardiometabolic biomarkers among US white and black postmenopausal women

BACKGROUND

Concentrations of 25-hydroxyvitamin D [25(OH)D] tend to be lower in African Americans than in non-Hispanic whites, but whether adding information on parathyroid hormone (PTH) can help explain the higher cardiometabolic risk among African Americans is unknown.

OBJECTIVES

This study examined race (black/white)-specific independent and joint associations of 25(OH)D and PTH with cardiometabolic biomarkers including high-sensitivity C-reactive protein (hs-CRP), estimated glomerular filtration rate (eGFR), and homeostasis model assessment of insulin resistance (HOMA-IR) and β-cell function (HOMA-B).

METHODS

Among 1500 white and 1300 black postmenopausal women without cardiovascular disease from the Women's Health Initiative Observational Study, a weighted linear regression analysis and a novel penalized spline-based semiparametric model with contour plots, accounting for possible nonlinear relations and interactions simultaneously, were used to investigate the race-specific independent and joint associations of 25(OH)D and PTH with each biomarker.

RESULTS

Black women had lower concentrations of 25(OH)D and higher PTH, HOMA-IR, HOMA-B, hs-CRP, and eGFR than white women (all P values < 0.0001). Lower 25(OH)D and higher PTH were each independently and jointly associated with higher HOMA-IR in both white and black women, whereas a similar joint relation with HOMA-B was observed in white women only. In contrast, PTH was nonlinearly associated with HOMA-B in black women and positively associated with hs-CRP in white women, independently of 25(OH)D. Whereas there was an inverse linear relation between PTH and eGFR in white women after accounting for 25(OH)D, PTH and 25(OH)D were jointly and nonlinearly associated with eGFR in black women.

CONCLUSIONS

We found that the joint association of 25(OH)D and PTH with β-cell function, systemic inflammation, and kidney function apparently differed between white and black women. Further studies are needed to determine whether differences in the vitamin D-PTH endocrine system contribute to racial disparities in cardiovascular health.

Euthyroid sick syndrome in hip fractures: Valuation of vitamin D and parathyroid hormone axis

INTRODUCTION

Femur fracture is an acute event with a high incidence and mortality worldwide. Euthyroid sick syndrome (ESS) is a disease characterized by an alteration of fT3 in the absence of a primary thyroid pathology. The aim of the study is evaluating the association between femur fracture and ESS and post-operative fluctuations of the parathyroid hormone (PTH) and vitamin D and their physio-pathological implications.

MATERIALS AND METHODS

All patients older than 65 years, admitted in our emergency care unit with a diagnosis of proximal femur fracture were recruited. Exclusion criteria were acute cardio-pulmonary events, neoplastic diseases, any thyroid or endocrine pathology and use of drugs with thyroidal interactions. All patients underwent surgery within 48 h from the injury. The outcome of the study is the presence of ESS, moreover, post-operative fluctuations of the PTH and vitamin D are also evaluated.

RESULT

45 patients (13 men and 32 females) were enrolled. 20 patients had a normal thyroidal function, while 23 had a diagnosis of ESS. Mean age was 81.9. BMI was lower in the ESS group than the controls (25,3 vs 22,7; p < 0.02). In the ESS group a significantly higher decrease in Vitamin D levels was observed, compared to controls (3.96 ng/ml, p<0.001). Values of PTH were significantly different between the two groups, with a level 44.29 pg/ml lower among the ESS group compared to controls (p = 0.002). In the ESS group a significant decrease of serum calcium on the first post-surgery day was observed, compared to controls (8,7 vs 8,3; p < 0,01). There were no differences in the CCI, serum electrolytes and other variables collected between the two groups.

CONCLUSION

Part of the geriatric population suffering from fractures of the proximal femur are affected by ESS. This population displays anomalies of the Vitamin d-PTH axis and a lower BMI.

Lower total 25-hydroxyvitamin D but no difference in calculated or measured free 25-hydroxyvitamin D serum levels in patients with primary hyperparathyroidism

To evaluate the measured free 25-hydroxyvitamin D [25(OH)D] levels in patients with hyperparathyroidism (PHPT) and healthy controls. Eighty patients with PHPT(n = 40) and age and BMI matched controls (n = 40) were examined. Serum levels of total or free 25(OH)D, vitamin D binding protein (DBP), intact parathyroid hormone (iPTH) and calcium were measured. There was no significant difference in age (61.2 ± 11.9 vs 60.2 ± 7.0 years) and BMI (30.0 ± 6.1 vs 30.0 ± 2.2 kg/m²) between PHPT patients and healthy subjects. Levels of total 25(OH)D were about 20 % lower in PHPT patients (26.4 ± 7.7 ng/mL) compared to controls (31.0 ± 7.8 ng/mL, P < 0.05). There were no significant differences in calculated or measured free 25(OH)D levels between PHPT patients (4.9 ± 1.8 or 4.9 ± 1.6 pg/mL, respectively) and control subjects (5.1 ± 1.2 or 5.3 ± 1.6 pg/mL, respectively). Levels of free 25(OH)D were positively associated with levels of total 25(OH)D (r = 0.28, P < 0.05) but negatively correlated with iPTH and calcium levels (r=-0.22 and -0.23 respectively, P < 0.05). Serum total 25(OH)D levels were lower but the calculated or measured free 25(OH)D levels in patients with PHPT did not differ from healthy subjects. We suggest that total 25(OH)D levels may not reflect true vitamin D nutritional status in patients with PHPT.

Inflammatory markers in end-stage renal disease patients on haemodialysis

Background

CXC chemokine ligand 16 (CXCL16) is an inflammatory chemokine that mediates renal infiltration of macrophages and activated T cells. Aim: To investigate serum levels of CXCL16 in patients undergoing hemodialysis and their correlation with other inflammatory markers such as C-reactive protein (CRP) and intact parathyroid hormone (iPTH).

Methods

The study included 40 hemodialysis patients (22 males) and 40 age and gender-matched controls (24 males). Fasting blood sugar (FBS), urea, creatinine, calcium and inorganic phosphorous were assayed in participants using routine methods, glycosylated hemoglobin (HbA1c) by quantitative chromatographic spectrophotometry, iPTH by chemiluminescent microparticle immunoassay, CRP by nephelometry and CXCL16 by ELISA technique.

Results

Serum CXCL16, CRP, PTH, FBS, HbA1c, phosphorus, urea, and creatinine levels were significantly higher in hemodialysis patients compared to controls (p<0.00001). No statistically significant differences were observed between patients and controls for calcium. Serum CXCL16 levels correlated positively with CRP (r=0.956, p<0.00001) and iPTH (r=-0.403, p<0.001). Hemodialysis patients (diabetics or hypertensives) had significantly higher CXCL16 levels compared to non-diabetics or non-hypertensives.

Conclusions

High levels of serum CXCL16, CRP and iPTH reflect the inflammatory status of hemodialysis patients and help avoid complications. Serum CXCL16 could be used as a biomarker together with CRP in these patients.

25-Hydroxyvitamin D and Vitamin D Binding Protein Levels in Patients With Primary Hyperparathyroidism Before and After Parathyroidectomy

Objective: To evaluate vitamin D binding protein and free 25-hydroxyvitamin D [25(OH)D] levels in healthy controls compared to primary hyperparathyroidism (PHPT) patients, and to examine PHPT before and after surgery. Methods: Seventy-five PHPT patients and 75 healthy age, gender, and body mass index (BMI) -matched control subjects were examined. In addition, 25 PHPT patients underwent parathyroidectomy and had a 3-month follow up visit. Levels of total and free 25(OH)D, DBP, and intact parathyroid hormone (iPTH) were determined before and 3 months after surgery. Results: There was no significant difference in age and BMI between PHPT patients and controls. Levels of 25(OH)D and DBP were lower in PHPT patients compared to controls (p < 0.01). There was no significant difference in calculated free and bioavailable 25(OH)D levels between PHPT patients and controls. Calcium and iPTH levels decreased to normal but DBP and DBP-bound-25(OH)D increased (P < 0.001) after parathyroidectomy. Levels of DBP were inversely correlated with iPTH (r = -0.406, P < 0.001) and calcium levels (r = -0.423, P < 0.001). Conclusion: Serum DBP levels were lower in patients with PHPT and parathyroidectomy restored DBP levels. We suggest that lower DBP levels is one of contributing mechanisms of low total 25(OH)D in PTHP patients and the total 25(OH)D levels might not reflect true vitamin D status in PHPT patients.

Treatment of osteoporosis with recombinant parathyroid hormone, utilisation of total body DXA to observe treatment effects on total body composition and factors determining response to therapy

PURPOSE

Recombinant parathyroid hormone (rPTH) increases bone mineral density (BMD). However, certain other potential effects of rPTH remain to be studied. The aim of this study is to identify whether bone turnover markers, relevant biochemical parameters or total body fat and muscle composition affect the response to rPTH and to establish if these parameters in particular change during treatment.

METHODS

One hundred seventy-two participants were treated with rPTH, and 128 subjects who fully complied with the therapy and completed their investigations including biochemical bone markers and total body composition at baseline, 6 months and 1 year of the treatment were divided into responder and non-responder groups. A total body dual-energy X-ray absorptiometry (DXA) scanner was used to assess the body muscle, fat and bone composition.

RESULTS

rPTH significantly increased BMD spine at 1 year (p = 0.000). Twenty-four-hour urinary calcium was significantly increased at 6 months in the responder group (p = 0.00). There was a trend to an increase in the fat and muscle mass (p = 0.52 and 0.45, respectively), and it was not negatively affected by rPTH. Bone turnover markers (P1NP and OC) did not show statistically significant difference over time between responders and non-responders (p = 0.74 and p = 0.19, respectively).

CONCLUSIONS

Hypercalciuria which is a frequent feature in osteoporotic population may predict non-responders at 6 months of rPTH, and it may help to optimise individual patient's treatment. Unlike endogenous PTH in pathological conditions, rPTH is anabolic to bone and has no detrimental effects on the body fat and muscle composition.

Metabolic Effects of Single-Dose Pamidronate Administration in Prostate Cancer Patients with Bone Metastases

Background

Increased osteolysis usually accompanies sclerotic bone metastases from prostate cancer. This provides a rationale for the use of bisphosphonates to treat bone pain and prevent skeletal complications.

Methods

The fasting urinary levels of calcium, hydroxyproline (OHPRO), pyridinolines (PYD), deoxypyridinolines (DPYD), collagen cross-linked N-telopeptide (NTX) and the serum values of calcium, total alkaline phosphatase and relevant bone isoenzyme, bone gla protein (BGP), carboxy-telopeptide of type I collagen (ICTP) and parathyroid hormone (PTH) were determined at baseline and on the 15th, 30th, 60th and 90th days after single-dose (90 mg) pamidronate administration in 35 consecutive prostate cancer patients with bone metastases. These biochemical indices and serum interleukin 6 (IL-6) were also measured after four days in the last consecutive 17 cases.

Results

PYD, DPYD and NTX showed a significant decrease lasting four weeks (p<0.01, <0.01 and <0.001, respectively). OHPRO and ICTP did not change significantly. The NTX decline was greater than that of PYD and DPYD (maximum percent decrease: −71.3, −23.1 and −28.2, respectively). Bone formation markers and serum calcium did not change significantly. Serum PTH showed a rapid initial increase followed by a slow decrease (p<0.001). DPYD and NTX patterns did not correlate with changes in bone pain. As observed in the last 17 cases, the maximum osteolysis inhibition after pamidronate occurred on the fourth day after drug infusion. Serum IL-6 levels showed a short-lived decrease preceded by a transient rise on the fourth day.

Conclusions

Pamidronate is able to induce a decrease in bone resorption without significantly influencing bone formation. The maximum decrease in bone resorption occurs very early. NTX is the most sensitive bone resorption marker in bisphosphonate therapy monitoring. Changes in IL-6 but not bone resorption markers may be useful in the prediction of symptomatic response.

Dietary phosphate exacerbates intestinal inflammation in experimental colitis

The recent widespread consumption of Western diets and food additives worldwide is associated with excessive inorganic phosphate intake. However, researchers have known little about the impact of dietary phosphate intake on the development of inflammatory bowel disease to date. In this study, we investigated the effects of dietary phosphate on intestinal inflammation in experimental colitis. Sprague-Dawley rats were fed different phosphate diets (0.5%, 1.0% and 1.5% phosphate) with or without dextran sulfate sodium. For in vitro study, the effects of phosphate on proinflammatory cytokine induction and reactive oxygen species production in RAW264.7 macrophage were examined. Dietary phosphate exacerbated intestinal inflammation in experimental colitis in a dose-dependent manner, as assessed by the clinical disease activity score, colon length, and histology. Furthermore, the high phosphate diet increased myeloperoxidase activity and proinflammatory cytokine mRNA expression through the activation of nuclear factor κB in the inflamed colon. In addition, high phosphate loading in RAW264.7 cells directly enhanced reactive oxygen species production and proinflammatory cytokine gene expression. Our results demonstrated that the high phosphate diet exacerbated intestinal inflammation in experimental colitis. These findings have important therapeutic implications for inflammatory bowel disease patients.

Parathyroid Hormone Levels and High-Residual Platelet Reactivity in Patients Receiving Dual Antiplatelet Therapy With Acetylsalicylic Acid and Clopidogrel or Ticagrelor

BACKGROUND

High-residual-on-treatment platelet reactivity still represents a challenging issue, potentially vanishing the benefits of dual antiplatelet treatment in patients with coronary artery disease. However, very few is known on the determinants of suboptimal response to antiplatelet agents. Recent interests have emerged on the potential prothrombotic effect of parathyroid hormone (PTH). Therefore, the aim of the present study was to assess the impact of parathyroid hormone (PTH) on platelet reactivity in patients receiving DAPT after an acute coronary syndrome or PCI.

METHODS

Patients treated with DAPT (ASA and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30- to 90-days postdischarge. By whole blood impedance aggregometry, HRPR was considered for ASPI test >862 AU*min (for ASA) and ADP test values ≥417 AU*min (for ADP antagonists).

RESULTS

We included 362 patients on DAPT, 125 (34.5%) receiving clopidogrel, and 237 (65.5%) on ticagrelor. Patients were divided according to PTH quartiles values (<45.8; 45.8-60.3; 60.4-88; ≥88.1 pg/mL). Higher PTH was associated with older age (P = 0.001); renal failure (P < 0.001), higher HDL cholesterol (P = 0.006) and creatinine (P < 0.001) and lower 25-OH cholecalciferol (P < 0.001). Suboptimal response to ASA was infrequent (2.8%), and not influenced by the levels of PTH (P = 0.57). ADP-mediated platelet aggregation was significantly increased in patients with higher PTH (P = 0.03), with an absolute increase in the prevalence of HRPR to ADP antagonists for higher PTH (24.7% vs. 40%, P = 0.007 for 4th vs. 1-3rd quartiles, adjusted OR[95%CI] = 2.04[1.14-3.64], P = 0.02). By the use of the ROC curve, we identified PTH levels above 96.7 pg/mL as the best predictor of HRPR with ADP antagonists (adjusted OR[95%CI] = 2.52[1.31-4.87], P = 0.006). Higher rate of HRPR was confirmed for PTH >96.7 pg/mL among the subgroup of patients on clopidogrel (51.5 vs. 85.7%, P = 0.001; adjusted OR[95%CI] = 12.5[2.6-60.9], P = 0.002), but not among ticagrelor-treated patients (11.3 vs. 16.7%, P = 0.31; adjusted OR[95%CI] = 1.55[0.56-4.6], P = 0.42).

CONCLUSION

In patients receiving dual antiplatelet therapy for coronary artery disease, higher PTH levels are associated with an increased ADP-mediated platelet reactivity and suboptimal response to clopidogrel, especially for values above 96.7 pg/mL, while not influencing the effectiveness of ASA and ticagrelor.

Association between parathyroid hormone levels and inflammatory markers among US adults

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.

De novo autoimmune hepatitis associated with PTH(1-34) and PTH(1-84) administration for severe osteoporosis in a liver transplant patient

De novo autoimmune hepatitis (AIH) is a rare graft dysfunction occurring in patients having undergone liver transplantation (LT) for causes other than AIH. We describe for the first time a case of de novo AIH associated with the administration of parathyroid hormone 1-34 [PTH(1-34)] and PTH(1-84) for severe osteoporosis. A 61-year-old woman was referred to our metabolic bone clinic due to severe osteoporosis, 3 years after LT for primary biliary cirrhosis. Initial treatment with PTH(1-34) led to asymptomatic hypertransaminasemia (two-fold the upper limit of normal), which normalized after drug discontinuation. A new flare of transaminases (three-fold the upper limit of normal) along with elevated alkaline phosphatase was observed after administration of PTH(1-84), which did not resolve after PTH(1-84) withdrawal. Subsequently, after exclusion of common causes of liver enzyme elevation, a liver biopsy was performed. Histological findings showed de novo AIH, which responded rapidly to treatment with methylprednisolone.

Aging and bone loss: new insights for the clinician

It is well known that the underlying mechanisms of osteoporosis in older adults are different than those associated with estrogen deprivation. Age-related bone loss involves a gradual and progressive decline, which is also seen in men. Markedly increased bone resorption leads to the initial fall in bone mineral density. With increasing age, there is also a significant reduction in bone formation. This is mostly due to a shift from osteoblastogenesis to predominant adipogenesis in the bone marrow, which also has a lipotoxic effect that affects matrix formation and mineralization. We review new evidence on the pathophysiology of age-related bone loss with emphasis upon the mechanism of action of current osteoporosis treatments. New potential treatments are also considered, including therapeutic approaches to osteoporosis in the elderly that focus on the pathophysiology and potential reversal of adipogenic shift in bone.

Phosphate: a stealthier killer than previously thought?

The kidneys excrete excess dietary phosphate, and patients with chronic kidney disease may suffer from phosphate overload and hyperphosphatemia. In chronic kidney disease, hyperphosphatemia has emerged as a risk factor for vascular calcification, cardiovascular mortality, left ventricular hypertrophy, and progression of chronic kidney disease. Serum phosphate at the upper limits of normal has also been associated with adverse outcomes in patients with relatively preserved kidney function. Of note, hyperphosphatemia is not a sensitive indicator of phosphate overload. In this regard, increased circulating fibroblast growth factor-23, a phosphatonin that is released in response to phosphate overload, is independently associated with adverse outcomes in patients with and without chronic kidney disease. Direct effects of extracellular phosphate on vascular calcification or cardiovascular cell biology; adverse consequences of adaptive mechanisms activated to limit phosphate overload, such as left ventricular hypertrophy induced by fibroblast growth factor-23; or epidemiological associations of additional cardiovascular risk factors with chronic kidney disease may underlie these observations. We now review the pathophysiology of phosphate, its relationship with cardiovascular outcomes, the potential consequences for patient care related to dietary phosphate and phosphate binders, and the clinical relevance for patients without overt chronic kidney disease.

Proteoglycan 4: a dynamic regulator of skeletogenesis and parathyroid hormone skeletal anabolism

Proteoglycan 4 (Prg4), known for its lubricating and protective actions in joints, is a strong candidate regulator of skeletal homeostasis and parathyroid hormone (PTH) anabolism. Prg4 is a PTH-responsive gene in bone and liver. Prg4 null mutant mice were used to investigate the impact of proteoglycan 4 on skeletal development, remodeling, and PTH anabolic actions. Young Prg4 mutant and wild-type mice were administered intermittent PTH(1-34) or vehicle daily from 4 to 21 days. Young Prg4 mutant mice had decreased growth plate hypertrophic zones, trabecular bone, and serum bone formation markers versus wild-type mice, but responded with a similar anabolic response to PTH. Adult Prg4 mutant and wild-type mice were administered intermittent PTH(1-34) or vehicle daily from 16 to 22 weeks. Adult Prg4 mutant mice had decreased trabecular and cortical bone, and blunted PTH-mediated increases in bone mass. Joint range of motion and animal mobility were lower in adult Prg4 mutant versus wild-type mice. Adult Prg4 mutant mice had decreased marrow and liver fibroblast growth factor 2 (FGF-2) mRNA and reduced serum FGF-2, which were normalized by PTH. A single dose of PTH decreased the PTH/PTHrP receptor (PPR), and increased Prg4 and FGF-2 to a similar extent in liver and bone. Proteoglycan 4 supports endochondral bone formation and the attainment of peak trabecular bone mass, and appears to support skeletal homeostasis indirectly by protecting joint function. Bone- and liver-derived FGF-2 likely regulate proteoglycan 4 actions supporting trabeculae formation. Blunted PTH anabolic responses in adult Prg4 mutant mice are associated with altered biomechanical impact secondary to joint failure.

Lower concentrations of serum phosphorus within the normal range could be associated with less calcification of the coronary artery in Koreans with normal renal function

BACKGROUND

Serum phosphorus concentrations are associated with an increased risk of cardiovascular disease (CVD) and mortality in patients with renal insufficiency. This association has also been reported in Western individuals without chronic kidney disease (CKD).

OBJECTIVE

It is unclear, however, whether this correlation occurs in Korean individuals without CKD, who usually ingest less phosphorus than do Western individuals.

DESIGN

We reviewed the findings in 402 healthy Korean adults with a mean (±SD) age of 50.8 ± 8.5 y (n = 257 men and 145 women) and a glomerular filtration rate of 83.5 ± 14.1 mL/min, who underwent health screening with electron-beam computed tomography (EBCT). The study population was separated into 4 groups on the basis of the coronary calcium concentration (Agatston score: 0, >0 to ≤10, >10 to ≤100, and >100). Mean serum phosphorus concentrations, measured ≥10 y before EBCT, were compared.

RESULTS

Multivariate analysis showed that age (P = 0.001), male sex (P = 0.002), family history of CVD (P = 0.006), serum glucose (P = 0.003), and serum phosphorus >3.6 mg/dL (P = 0.008) were significant factors influencing the coronary calcification group with an Agatston score >100, when those with an Agatston score of 0 were considered as the reference group. Compared with the group with a serum phosphorus concentration ≤3.3 mg/dL, the OR of an Agatston score >100 in individuals with a serum phosphorus concentration >3.6 to ≤3.9 mg/dL was 3.89 (95% CI: 1.43, 10.63; P = 0.008) and in those with a serum phosphorus concentration >3.9 mg/dL was 3.17 (95% CI: 1.19, 8.41; P = 0.021).

CONCLUSION

A lower concentration of serum phosphorus within the normal range could be associated with less calcification of the coronary artery in Koreans with normal renal function.

Long-term aerobic exercise and omega-3 supplementation modulate osteoporosis through inflammatory mechanisms in post-menopausal women: a randomized, repeated measures study

BACKGROUND

Evidence indicates that dietary fats and physical activity influence bone health. The purpose of this study was to examine the effects of long-term aerobic exercise and omega-3 (N-3) supplementation on serum inflammatory markers, bone mineral density (BMD), and bone biomarkers in post-menopausal women.

METHODS

Seventy-nine healthy sedentary post-menopausal women aged 58-78 years participated in this study. Subjects were randomized to one of 4 groups: exercise + supplement (E+S, n = 21), exercise (E, n = 20), supplement (S, n = 20), and control (Con, n = 18) groups. The subjects in the E+S and E groups performed aerobic exercise training (walking and jogging) up to 65% of HRmax, three times a week for 24 weeks. Subjects in the E+S and S groups consumed 1000 mg/d N-3 for 24 weeks. The lumbar spine (L2-L4) and femoral neck BMD, serum tumor necrosis factor (TNF) α, interleukin (IL) 6, prostaglandin (PG) E2, estrogen, osteocalcin, 1, 25-dihydroxyvitamin D3 (1, 25 Vit D), C-telopeptide (CTX), parathyroid hormone (PTH) and calcitonin (CT) were measured at baseline, the end of week 12 and 24.

RESULTS

Serum estrogen, osteocalcin, 1, 25 Vit D, CT, L2-L4 and femoral neck BMD measures increased (P < 0.05) and the serum CTX, PTH, TNF-α, IL-6, and PGE2 decreased (P < 0.05) in E + S group after the 24 wk intervention but not in the E or S intervention groups. L2-L4 and femoral neck BMD, estrogen, osteocalcin, and CT were negatively (P < 0.05) correlated with TNF-α and PGE2. PTH and CT were correlated positively and negatively with IL-6, respectively (P < 0.05).

CONCLUSIONS

The present study demonstrates that long-term aerobic exercise training plus N-3 supplementation have a synergistic effect in attenuating inflammation and augmenting BMD in post-menopausal osteoporosis.

Changes in healthy elderly women's physical performance: a 3-year follow-up

BACKGROUND

Inflammatory states, hypovitaminosis D and secondary hyperparathyroidism may have a role in the age-related loss of muscle mass, and physical performance in healthy old people. The aim of this study is to investigate changes in muscle mass, strength and physical performance in healthy, active elderly females over a 3-year follow-up, correlating them with any inflammatory states and PTH and 25-hydroxyvitamin D (25-OHD) levels.

METHODS

One hundred healthy females over 65 years of age routinely attending a twice-weekly mild fitness program were eligible for the study. Clinical history, serum parameters, body composition by DEXA, handgrip strength, knee extensor isometric/isotonic strength and functional performance measured using the Short Physical Performance Battery (SPPB) were evaluated at the baseline and after 3 years.

RESULTS

After 3 years, the women had a significant decrease in weight (∆:-0.8±3.1 kg; p<0.05) and height (∆:-0.4±0,6 cm; p<0.001), while their BMI and body composition parameters did not change. Only IL-6 (∆: 0.6±2.0; p<0.01) and PTH (∆: 30.7±29.2 ng/L; p<0.001) increased significantly, while there were no changes in 25-OHD levels. There was a significant decrease in all the SPPB results and in muscle strength. ∆ PTH only correlated with the variation in 4-meter walking speed (r: 0.41; p<0.01).

CONCLUSIONS

With advancing age, physical performance declines even in healthy, active females despite a spare of muscle mass. The increase in PTH seems to have a role in this decline, that could be clarified by further investigations.

Independent and combined effects of exercise and vitamin D on muscle morphology, function and falls in the elderly

Regular exercise, particularly progressive resistance training (PRT), is recognized as one of the most effective strategies to prevent age-related muscle loss (sarcopenia), but its effects on muscle function are mixed. However, emerging data indicates that high velocity PRT (fast concentric muscle contractions) is more effective for improving functional outcomes than traditional PRT. In terms of falls prevention, high-challenging balance training programs appear to be most effective. There is also compelling evidence that supplemental vitamin D is an effective therapeutic option for falls prevention. The findings from a recent meta-analysis revealed that supplemental vitamin D at a dose of at least 700–1,000 IU/d or an achieved serum 25(OH)D level of at least 60 nmol/L was associated with reduced falls risk among older individuals. Based on these findings, it is possible that the combination of exercise and vitamin D could have a synergistic effect on muscle morphology and function, particularly since both interventions have been shown to have beneficial effects on type II “fast twitch” muscle fibers and systemic inflammation, which have both been linked to losses in muscle mass and function. Unfortunately however, the findings from the limited number of factorial 2 × 2 design RCTs indicate that additional vitamin D does not enhance the effects of exercise on measures of muscle morphology, function or falls risk. However, none of these trials were adequately powered to detect a “synergistic” effect between the two treatment strategies, but it is likely that if an exercise-by-vitamin D interaction does exist, it may be limited to situations when vitamin D deficiency/insufficiency is corrected. Further targeted research in “high risk” groups is still needed to address this question, and evaluate whether there is a threshold level of serum 25(OH)D to maximize the effects of exercise on muscle and falls risk.

Relation of serum phosphorus levels to carotid intima-media thickness in asymptomatic young adults (from the Bogalusa Heart Study)

Increased serum phosphorus has been associated with increased mortality from cardiovascular (CV) disease. However, information is scant regarding the influence of serum phosphorus within the normal range on vascular risk in subclinical atherosclerosis in asymptomatic young adults. Serum phosphorus and other CV risk factor variables were measured in 856 white and 354 black subjects without known CV disease or renal disease. Carotid intima-media thickness (IMT) was measured by B-mode ultrasonography. Significant race and gender differences were noted for serum phosphorus (blacks > whites) and carotid IMT (black women > white women; men > women). In bivariate analyses, serum phosphorus was correlated with carotid IMT (p <0.001), and smokers showed higher phosphorus levels than nonsmokers (p = 0.008). In multivariate regression analyses, carotid IMT was significantly associated with serum phosphorus (regression coefficient beta = 0.028, p <0.001) and smoking (beta = 0.032, p <0.001), adjusting for other CV risk factors and estimated glomerular filtration rate. In addition, a significant interaction effect of cigarette smoking and serum phosphorus on carotid IMT was noted, with a greater increasing trend of carotid IMT with phosphorus in smokers than in nonsmokers (p = 0.019 for interaction). In conclusion, serum phosphorus within the normal range is an important correlate of carotid IMT in asymptomatic young adults, with smoking potentiating this adverse association.

Vitamin D and bone health: potential mechanisms

Osteoporosis is associated with increased morbidity, mortality and significant economic and health costs. Vitamin D is a secosteriod hormone essential for calcium absorption and bone mineralization which is positively associated with bone mineral density [BMD]. It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. Sub-optimal vitamin D status has been reported in many populations but it is a particular concern in older people; thus there is clearly a need for effective strategies to optimise bone health. A number of recent studies have suggested that the role of vitamin D in preventing fractures may be via its mediating effects on muscle function (a defect in muscle function is one of the classical signs of rickets) and inflammation. Studies have demonstrated that vitamin D supplementation can improve muscle strength which in turn contributes to a decrease in incidence of falls, one of the largest contributors to fracture incidence. Osteoporosis is often considered to be an inflammatory condition and pro-inflammatory cytokines have been associated with increased bone metabolism. The immunoregulatory mechanisms of vitamin D may thus modulate the effect of these cytokines on bone health and subsequent fracture risk. Vitamin D, therefore, may influence fracture risk via a number of different mechanisms.

Serum 25-hydroxyvitamin D levels modulate the acute-phase response associated with the first nitrogen-containing bisphosphonate infusion

The acute-phase response (APR) is the most frequent side effect after the first dose of intravenous nitrogen-containing bisphosphonates (N-BPs). It has been demonstrated in vitro that N-BPs stimulate gammadelta T-cell proliferation and production of cytokines and that vitamin D is able to modulate them. Therefore, we have studied the relationship between bone metabolism parameters, particularly for 25-hydroxyvitamin D [25(OH)D], and APR in patients treated with 5 mg zoledronic acid intravenously. Ninety N-BP-naive osteoporotic women (63.7 +/- 10.6 years of age) were stratified for the occurrence of APR (APR(+)) or not (APR(-)) and quantified by body temperature and C-reactive protein (CRP). The APR(+) women had significantly lower 25(OH)D levels than the APR(-) women. Levels of 25(OH)D were normal (>30 ng/mL) in 31% of APR(+) women and in 76% of APR(-) women. The odds ratio (OR) to have APR in 25(OH)D-depleted women was 5.8 [95% confidence interval (CI) 5.30-6.29; p < .0002] unadjusted and 2.38 (95% CI 1.85-2.81; p < .028) after multiple adjustments (for age, body mass index, CRP, calcium, parathyroid hormone, and C-telopeptide of type I collagen). Levels of 25(OH)D were negatively correlated with postdose body temperature (r = -0.64, p < .0001) and CRP (r = -0.79, p < .001). An exponential increase in fever and CRP has been found with 25(OH)D levels lower than 30 ng/mL and body temperature less than 37 degrees C, whereas normal CRP was associated with 25(OH)D levels above 40 ng/mL. The association between post-N-BPs APR and 25(OH)D suggests an interesting interplay among N-BPs, 25(OH)D, and the immune system, but a causal role of 25(OH)D in APR has to be proven by a randomized, controlled trial. However, if confirmed, it should have some practical implications in preventing APR.

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.

Effects of calcitriol on type 5b tartrate-resistant acid phosphatase and interleukin-6 in secondary hyperparathyroidism

BACKGROUND/AIMS

Secondary hyperparathyroidism (SHP) is characterized by high bone turnover and elevated serum bone remodeling markers. Elevation of serum interleukin-6 (IL-6) levels is also characteristic of end-stage renal disease. This study investigates the effects of intravenous calcitriol on serum bone resorptive markers, namely, type 5b tartrate-resistant acid phosphatase (TRACP5b) and IL-6 in patients with SHP.

METHODS

Intravenous calcitriol therapy was given for 16 weeks to 24 patients on maintenance hemodialysis with plasma intact parathyroid hormone (iPTH) levels >300 pg/ml. Blood was drawn at baseline and every 4 weeks for 16 weeks for determination of the levels of biochemical parameters, iPTH, IL-6 and bone remodeling markers, including bone-specific alkaline phosphatase (bAP) and TRACP5b.

RESULTS

Only 21 patients responded to the calcitriol therapy, with significant decrements in serum iPTH after 4 weeks of therapy and thereafter. After 16 weeks of calcitriol therapy, 21 patients had significant decrements in serum iPTH (707.9 +/- 317.8 vs. 205.0 +/- 63.1 pg/ml, p < 0.01). Prior to treatment, a significant correlation was found between increased levels of serum iPTH and IL-6 levels (r = 0.45, p < 0.05). After treatment, there was also a significant and parallel lowering of levels of serum iPTH, IL-6 (8.52 +/- 3.59 vs. 7.24 +/- 2.81 pg/ml, p < 0.01), bAP (54.68 +/- 36.17 vs. 24.55 +/- 13.84 U/l, p < 0.01) and TRACP5b (3.41 +/- 1.89 vs. 1.80 +/- 0.55 U/l, p < 0.01). Our results additionally showed significant positive correlationsbetween baseline levels of serum IL-6 and those of iPTH, bAP and TRACP5b. After 16 weeks of calcitriol treatment, the correlation between IL-6 and iPTH levels lost significance but levels of serum IL-6, bAP and TRACP5b remained significantly correlated.

CONCLUSIONS

Elevated levels of serum IL-6 and bone remodeling markers, namely, bAP and TRACP5b which are common features of SHP, are effectively suppressed by calcitriol therapy. This indicates that hyperparathyroidism not only accelerates bone remodeling but may also aggravate inflammation in patients on maintenance hemodialysis.

25-hydroxyvitamin D, parathyroid hormone, and functional recovery after hip fracture in elderly patients

There is increasing interest in the effects of vitamin D and parathyroid hormone (PTH) on extraskeletal tissues, including the muscle. These effects may explain impairment in functional ability found in vitamin D-deficient subjects. Our aim was to investigate the roles of vitamin D and PTH in affecting the ability to perform activities of daily living after hip fracture. We studied 456 of 521 hip-fracture patients admitted consecutively to a rehabilitation hospital. Functional outcome was assessed after acute inpatient rehabilitation by using the Barthel index score. The functional scores were significantly correlated with serum levels of 25-hydroxyvitamin D (rho = 0.190; P < 0.001) and PTH (rho = -0.164; P < 0.001) and the 25-hydroxyvitamin D/PTH ratio (rho = 0.261; P < 0.001). At multiple regression, 25-hydroxyvitamin D and PTH levels were independently associated with Barthel index scores. The correlation between the 25-hydroxyvitamin D/PTH ratio and Barthel index scores was significantly stronger than the one between 25-hydroxyvitamin D and Barthel index scores (difference between the two correlation coefficients = 0.071; 95% CI = 0.009-0.133; P = 0.011). The significant association between the 25-hydroxyvitamin D/PTH ratio and the Barthel index scores persisted after adjustment for 12 prognostic factors (P = 0.012). On the whole, the panel of prognostic factors we studied predicted 50.1% of the variance of the functional score. Data shows that PTH and 25-hydroxyvitamin D were significantly associated with the ability to function after hip fracture and suggest that the two hormones act through independent mechanisms. The 25-hydroxyvitamin D/PTH ratio significantly contributed to a predictive model of functional outcome.

Calcium supplementation does not affect CRP levels in postmenopausal women--a randomized controlled trial

INTRODUCTION

Epidemiological studies suggest that calcium supplementation may decrease the risk of cardiovascular disease.

METHODS

Since the inflammatory marker C-reactive protein (CRP) is a risk factor for cardiovascular disease, and CRP production is potentially responsive to parathyroid hormone, we measured high-sensitivity CRP at baseline and 12 months in a subset of healthy postmenopausal women participating in a randomized controlled trial of the effects of 1 g of calcium daily on the incidence of fractures.

RESULTS

At baseline, we found that CRP correlated positively with indices of body weight and fat and with bone mineral density (BMD) at the total body and total hip sites, but the associations between CRP and BMD were lost after adjustment for body weight. There were consistent associations between levels of CRP and markers of the metabolic syndrome (fat mass, plasma triglycerides, fasting glucose).

CONCLUSION

After 1 year of calcium supplementation, there was no difference between the groups in levels of CRP. We conclude that levels of CRP correlate with anthropometric and biochemical features of insulin resistance, but that they are neither predictive of BMD nor affected by 1 g of calcium supplementation in healthy postmenopausal women.

Interleukin-6: An osteotropic factor influencing bone formation?

Interleukin (IL)-6 has long been considered as an osteoresorptive factor. However, recent data indicate that IL-6 could influence bone formation in conditions of increased bone turnover. In this paper, the effects of IL-6 and its soluble receptor on osteoblast proliferation, differentiation and apoptosis are readdressed. A brief summary of IL-6 signaling after binding to its receptor is provided and hypotheses concerning IL-6 and the central control of bone formation are also highlighted.

Secondary hyperparathyroidism promotes the acute phase response – a rationale for supplemental Vitamin D in prevention of vascular events in the elderly

Parathyroid hormone (PTH) promotes IL-6 secretion by osteoblasts, and may also up-regulate IL-6 production in the liver and adipose tissue; this may explain why serum IL-6 is markedly elevated in primary hyperparathyroidism, and low in hypoparathyroidism. IL-6 is the chief stimulus to hepatic production of many acute phase reactants, notably fibrinogen and C-reactive protein (CRP). Mild secondary hyperparathyroidism is common in elderly people, particularly at high latitudes during the winter, owing to poor vitamin D status. This may rationalize evidence that acute phase proteins show seasonal variations and are typically elevated in the elderly, whereas leisure physical activity is associated with a reduction in these proteins. In a recent clinical trial targeting elderly chronically ill patients, administration of vitamin D reduced serum levels of both CRP and IL-6; further such studies should assess the impact of physiologically meaningful doses of vitamin D on acute phase reactants in elderly subjects likely to have poor vitamin D status. Since elevations of CRP and fibrinogen may increase risk for thromboembolic vascular events, these considerations may help to explain the excess of coronary mortality observed during winter months, and suggest a role for supplemental vitamin D in preservation of vascular health. Moderate alcohol intake is associated with reduced serum PTH as well as decreased levels of CRP and fibrinogen; conceivably, modulation of PTH mediates, at least in part, the favorable impact of moderate drinking on the acute phase reactants.

Short-term infusion of interleukin-6 does not induce insulin resistance in vivo or impair insulin signalling in rats

AIMS/HYPOTHESIS

Interleukin-6 has been implicated in the insulin resistance associated with obesity and impaired glucose tolerance. Previous studies in vitro have shown that IL-6 rapidly (1-2 h) impairs cellular insulin signalling and action through an increased expression of suppressor of cytokine signalling (SOCS)-3. In the present study, IL-6 or saline was infused in rats that were simultaneously in a state of hyperinsulinaemia. Muscle, liver and adipose tissue were excised after 2 h to examine potential effects on insulin signalling or gene expression.

METHODS

The rats were infused with IL-6 or saline during a euglycaemic-hyperinsulinaemic clamp and the glucose infusion rate was measured after 90 to 120 min. Signal transducer and activator of transcription (STAT)3 phosphorylation and insulin-stimulated tyrosine phosphorylation of the insulin receptors and IRS were measured with immunoblotting and gene expression through real-time PCR.

RESULTS

No inhibitory effect of IL-6 on insulin-stimulated whole-body glucose uptake was seen in spite of high circulating levels of IL-6 (0.85+/-0.08 nmol/l). Tyrosine phosphorylation of the insulin receptors and IRS was also unchanged in the liver, skeletal muscles and adipose tissue. However, tyrosine phosphorylation of STAT3 was increased in all tissues, showing that IL-6 signalling was activated. IL-6 mRNA tended to increase, while GLUT4, peroxisome proliferator-activated receptor-gamma coactivator-1 (PGC-1) and adiponectin gene expression were unchanged.

CONCLUSIONS/INTERPRETATION

Infusion of IL-6 for 120 min in rats during euglycaemic-hyperinsulinaemic conditions did not alter the effect of insulin on whole-body glucose homeostasis, plasma adiponectin levels or insulin signalling in target tissues. Thus, the acute effects of IL-6, associated with SOCS-3 induction, do not lead to whole-body insulin resistance. These data further underscore the importance of the chronic, and potentially tissue-specific effects of IL-6 on insulin signalling and action.

A moderately low phosphate intake may provide health benefits analogous to those conferred by UV light - a further advantage of vegan diets

Although exposure to ultraviolet light is often viewed as pathogenic owing to its role in the genesis of skin cancer and skin aging, there is growing epidemiological evidence that such exposure may decrease risk for a number of more serious cancers, may have a favorable impact on blood pressure and vascular health, and may help to prevent certain autoimmune disorders - in addition to its well-known influence on bone density. Most likely, these health benefits are reflective of improved vitamin D status. Increased synthesis or intake of vitamin D can be expected to down-regulate parathyroid hormone (PTH), and to increase autocrine synthesis of its active metabolite calcitriol in certain tissues; these effects, in turn, may impact cancer risk, vascular health, immune regulation, and bone density through a variety of mechanisms. Presumably, a truly adequate supplemental intake of vitamin D - manyfold higher than the grossly inadequate current RDA - could replicate the benefits of optimal UV exposure, without however damaging the skin. Diets moderately low in bioavailable phosphate - like many vegan diets - might be expected to have a complementary impact on disease risks, inasmuch as serum phosphate suppresses renal calcitriol synthesis while up-regulating that of PTH. A proviso is that the impact of dietary phosphorus on bone health is more equivocal than that of vitamin D. Increased intakes of calcium, on the other hand, down-regulate the production of both PTH and calcitriol - the latter effect may explain why the impact of dietary calcium on cancer risk (excepting colon cancer), hypertension, and autoimmunity is not clearly positive. An overview suggests that a vegan diet supplemented with high-dose vitamin D should increase both systemic and autocrine calcitriol production while suppressing PTH secretion, and thus should represent a highly effective way to achieve the wide-ranging health protection conferred by optimal UV exposure.

Changes in serum receptor activator of nuclear factor-kappaB ligand, osteoprotegerin, and interleukin-6 levels in patients with glucocorticoid-induced osteoporosis treated with human parathyroid hormone (1-34)

Changes in biochemical markers of bone turnover following intermittent injections of human (h)PTH (1-34) suggest that bone formation is initially favored over bone resorption. hPTH (1-34) is also known to influence osteoclast maturation and activity through modulation of osteoblast-derived cytokines, such as receptor activator of nuclear factor-kappaB ligand (RANKL), osteoprotegerin (OPG), IL-6, and IL-6 soluble receptor (IL-6sR). In this experiment, we investigated the changes in serum levels of soluble RANKL (sRANKL), OPG, IL-6, and IL-6sR in patients with glucocorticoid-induced osteoporosis treated with hPTH (1-34). Fifty-one postmenopausal women with glucocorticoid-induced osteoporosis were randomized to receive 12 months of 400 U hPTH (1-34) ( approximately 40 microg) daily and standard hormone replacement therapy, or hormone replacement therapy alone. Serum levels of sRANKL, OPG, IL-6, and IL-6sR were measured at baseline, 1 month, and every 3 months thereafter for a total of 24 months. hPTH (1-34) caused a rapid and significant increase in sRANKL within 1 month, and the levels remained elevated throughout the duration of therapy. IL-6 and IL-6sR increased significantly within 1 month, but returned to baseline levels more rapidly. In contrast, OPG was mildly suppressed beginning 6 months after hPTH therapy. These data support the hypothesis that hPTH (1-34) initially stimulates osteoblast maturation and function, which in turn leads to osteoclast activation and a gradual rebalancing of bone formation and resorption.

Interleukin-6, transforming growth factor-beta 1, and bone markers after kidney transplantation

The aim of this study was to investigate the relationship between interleukin 6 (IL-6), transforming growth factor (TGF)-beta 1, IL-6 soluble receptors, and biochemical parameters of bone turnover after kidney transplantation. Of 64 patients enrolled in the study, 19 received the kidney transplant 2 to 12 months before the study, and 45 within the previous 15 to 175 months. We measured IL-6, TGF-beta 1, intact parathyroid hormone (PTH) bone alkaline phosphatase (BALP), osteocalcin (OC), and procollagen type I propeptide (P1CP) concentrations in the serum, and deoxypyridinoline crosslinks (DPD) in the urine of the patients. In 16 patients in the first posttransplantation year, the concentrations of IL-6 (P = 0.02), TGF-beta 1 (P = 0.01), BALP (P = 0.0002), OC (P = 0.001), and DPD (P = 0.01) were significantly higher than in patients with longer posttranslation period. Statistically significant negative correlation was found between post-transplantation time and IL-6 (P = 0.04), BALP (P = 0.003), OC (P = 0.0009), P1CP (P = 0.03), and DPD (P = 0.01) concentrations. Repeated measurements of the investigated parameters in the first post-transplantation year showed a significant decrease only in TGF-beta I level. In all patients, IL-6 correlated positively with PTH (P = 0.0009) and DPD (P = 0.03), and IL-6 soluble receptor (IL-6 sR) with DPD (P = 0.03). A decrease in IL-6 and TGF-beta 1 concentrations that paralleled the decrease in bone turnover markers in the posttransplantation period indicated that IL-6 and TGF-beta 1 were probably involved in the bone turnover after kidney transplantation.

Low vitamin D and high parathyroid hormone levels as determinants of loss of muscle strength and muscle mass (sarcopenia): the Longitudinal Aging Study Amsterdam

The age-related change in hormone concentrations has been hypothesized to play a role in the loss of muscle mass and muscle strength with aging, also called sarcopenia. The aim of this prospective study was to investigate whether low serum 25-hydroxyvitamin D (25-OHD) and high serum PTH concentration were associated with sarcopenia. In men and women aged 65 yr and older, participants of the Longitudinal Aging Study Amsterdam, grip strength (n = 1008) and appendicular skeletal muscle mass (n = 331, using dual-energy x-ray absorptiometry) were measured in 1995-1996 and after a 3-yr follow-up. Sarcopenia was defined as the lowest sex-specific 15th percentile of the cohort, translating into a loss of grip strength greater than 40% or a loss of muscle mass greater than 3%. After adjustment for physical activity level, season of data collection, serum creatinine concentration, chronic disease, smoking, and body mass index, persons with low (<25 nmol/liter) baseline 25-OHD levels were 2.57 (95% confidence interval 1.40-4.70, based on grip strength) and 2.14 (0.73-6.33, based on muscle mass) times more likely to experience sarcopenia, compared with those with high (>50 nmol/liter) levels. High PTH levels (>or=4.0 pmol/liter) were associated with an increased risk of sarcopenia, compared with low PTH (<3.0 pmol/liter): odds ratio = 1.71 (1.07-2.73) based on grip strength, odds ratio = 2.35 (1.05-5.28) based on muscle mass. The associations were similar in men and women. The results of this prospective, population-based study show that lower 25-OHD and higher PTH levels increase the risk of sarcopenia in older men and women.

A review of anabolic therapies for osteoporosis

Osteoporosis results from a loss of bone mass and bone structure such that the bone becomes weak and fractures with very little trauma. Until recently, the approved osteoporosis therapies prevented more bone loss by altering osteoclast activity and lifespan. Recently, attention has turned away from osteoclast inhibition to agents that can stimulate the osteoblast to form new bone, or anabolic agents. This article reviews both approved and experimental anabolic agents that improve bone mass by improving osteoblast activity, or increasing osteoblast number. The use of the anabolic agents to improve bone mass and strength followed by agents that prevent the new bone mass from being lost may offer the ability to cure osteoporosis and reduce bone fracture healing time.