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Jane Fletcher Nutrition Nurses, University Hospitals Birmingham NHS Trust, Queen Elizabeth Hospital Birmingham, Mindelsohn Way, Edgbaston, Birmingham, UK
School of Nursing, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, UK

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Emma L Bishop Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK

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Stephanie R Harrison Leeds Institute of Rheumatic and Musculoskeletal Medicine, Chapel Allerton Hospital, Leeds, UK

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Amelia Swift School of Nursing, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, UK

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Sheldon C Cooper Gastroenterology Department, University Hospitals Birmingham NHS Trust, Queen Elizabeth Hospital Birmingham, Mindelsohn Way, Edgbaston, Birmingham, UK

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Sarah K Dimeloe Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK

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Karim Raza Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK

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Martin Hewison Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK

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Vitamin D has well-documented effects on calcium homeostasis and bone metabolism but recent studies suggest a much broader role for this secosteroid in human health. Key components of the vitamin D system, notably the vitamin D receptor (VDR) and the vitamin D-activating enzyme (1α-hydroxylase), are present in a wide array of tissues, notably macrophages, dendritic cells and T lymphocytes (T cells) from the immune system. Thus, serum 25-hydroxyvitamin D (25D) can be converted to hormonal 1,25-dihydroxyvitamin D (1,25D) within immune cells, and then interact with VDR and promote transcriptional and epigenomic responses in the same or neighbouring cells. These intracrine and paracrine effects of 1,25D have been shown to drive antibacterial or antiviral innate responses, as well as to attenuate inflammatory T cell adaptive immunity. Beyond these mechanistic observations, association studies have reported the correlation between low serum 25D levels and the risk and severity of human immune disorders including autoimmune diseases such as inflammatory bowel disease, multiple sclerosis, type 1 diabetes and rheumatoid arthritis. The proposed explanation for this is that decreased availability of 25D compromises immune cell synthesis of 1,25D leading to impaired innate immunity and over-exuberant inflammatory adaptive immunity. The aim of the current review is to explore the mechanistic basis for immunomodulatory effects of 25D and 1,25D in greater detail with specific emphasis on how vitamin D-deficiency (low serum levels of 25D) may lead to dysregulation of macrophage, dendritic cell and T cell function and increase the risk of inflammatory autoimmune disease.

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Rong Xu Center for Endocrine Metabolism and Immune Diseases, Lu He Hospital, Capital Medical University, Beijing, China
Beijing Key Laboratory of Diabetes Research and Care, Beijing, China

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Difei Lian Center for Endocrine Metabolism and Immune Diseases, Lu He Hospital, Capital Medical University, Beijing, China
Beijing Key Laboratory of Diabetes Research and Care, Beijing, China

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Yan Xie Center for Endocrine Metabolism and Immune Diseases, Lu He Hospital, Capital Medical University, Beijing, China
Beijing Key Laboratory of Diabetes Research and Care, Beijing, China

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Lin Mu Center for Endocrine Metabolism and Immune Diseases, Lu He Hospital, Capital Medical University, Beijing, China
Beijing Key Laboratory of Diabetes Research and Care, Beijing, China

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Yali Wu Center for Endocrine Metabolism and Immune Diseases, Lu He Hospital, Capital Medical University, Beijing, China
Beijing Key Laboratory of Diabetes Research and Care, Beijing, China

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Zhilei Chen Center for Endocrine Metabolism and Immune Diseases, Lu He Hospital, Capital Medical University, Beijing, China
Beijing Key Laboratory of Diabetes Research and Care, Beijing, China

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Baoyu Zhang Center for Endocrine Metabolism and Immune Diseases, Lu He Hospital, Capital Medical University, Beijing, China
Beijing Key Laboratory of Diabetes Research and Care, Beijing, China

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Osteoporosis (OP) is a systemic bone disease in which bone density and quality decrease and bone fragility increases due to a variety of causes, making it prone to fractures. The development of OP is closely related to oxidative stress. Uric acid (UA) is the end product of purine metabolism in the human body. Extracellular UA has antioxidant properties and is thought to have a protective effect on bone metabolism. However, the process of UA degradation can lead to intracellular oxidative stress, which together with UA-induced inflammatory factors, leads to increased bone destruction. In addition, UA can inhibit vitamin D production, resulting in secondary hyperparathyroidism and further exacerbating UA-associated bone loss. This review summarizes the relationship between serum UA levels and bone mineral density, bone turnover markers, and so on, in the hope of providing new insights into the pathogenesis and treatment of OP.

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Natércia Neves Marques de Queiroz University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Franciane Trindade Cunha de Melo University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Fabrício de Souza Resende University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Luísa Corrêa Janaú University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Norberto Jorge Kzan de Souza Neto University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Manuela Nascimento de Lemos University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Ana Carolina Lobato Virgolino University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Maria Clara Neres Iunes de Oliveira University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Angélica Leite de Alcântara University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Lorena Vilhena de Moraes University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Tiago Franco David University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Wanderson Maia da Silva University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Scarlatt Souza Reis University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Márcia Costa dos Santos University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Ana Carolina Contente Braga de Souza University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Pedro Paulo Freire Piani University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Neyla Arroyo Lara Mourão University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Karem Mileo Felício University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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João Felício Abrahão Neto University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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João Soares Felício University Hospital João de Barros Barreto, Federal University of Pará, Endocrinology Division, Belem, Pará, Brazil

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Objective:

Investigate the prevalence of vitamin D deficiency in an equatorial population through a large-sample study.

Methods:

Cross-sectional study with 30,224 healthy individuals from the North Region, in Brazil (Amazônia – state of Pará), who had 25-hydroxy-vitamin D (25(OH)D) and intact parathyroid hormone (PTH) serum levels measured by immunoassay method. Those with history of acute or chronic diseases were excluded. Abnormal levels of calcium, creatinine, glycemia and albumin were also exclusion criteria.

Results:

25(OH)D levels were 29.1 ± 8.2 ng/mL and values <12.7 ng/mL were equal to < −2 s.d. below average. Hypovitaminosis D was present in 10% of subjects according to the Institute of Medicine (values <20 ng/mL) and in 59%, in consonance with Endocrine Society (values 20–30 ng/mL as insufficiency and <20 ng/mL as deficiency) criteria. Individuals were divided according to four age brackets: children, adolescents, adults and elderly, and their 25(OH)D levels were: 33 ± 9; 28.5 ± 7.4; 28.3 ± 7.7; 29.3 ± 8.5 ng/mL, respectively. All groups differed in 25(OH)D, except adolescents vs adults. Regression model showed BMI, sex, living zone (urban or rural) and age as independent variables to 25(OH)D levels. Comparing subjects with vitamin D deficiency (<20 ng/mL) to those with vitamin D insufficiency (20–30 ng/mL), a difference between PTH levels in these two groups was observed (95.9 ± 24.7 pg/mL vs 44.2 ± 64.5 pg/mL; P < 0.01). Additionally, the most accurate predictive vitamin D level for subclinical hyperparathyroidism in ROC curve was 26 ng/mL.

Conclusion:

Our equatorial population showed low prevalence of vitamin D hypovitaminosis ranging with age bracket. The insufficient category by Endocrine Society was corroborated by our PTH data.

Open access
Elena Valassi Endocrinology/Medicine Department, Hospital Sant Pau, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER, Unidad 747), IIB-Sant Pau, ISCIII and Universitat Autònoma de Barcelona (UAB), Barcelona, Spain

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Natalia García-Giralt URFOA, IMIM (Institut Hospital del Mar d’Investigacions Mèdiques), Universitat Autònoma de Barcelona, Barcelona, Spain

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Jorge Malouf Mineral Metabolism Unit, Medicine Department, Hospital Sant Pau, Barcelona, Spain

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Iris Crespo Endocrinology/Medicine Department, Hospital Sant Pau, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER, Unidad 747), IIB-Sant Pau, ISCIII and Universitat Autònoma de Barcelona (UAB), Barcelona, Spain

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Jaume Llauger Radiology Department, Hospital Sant Pau, Barcelona, Spain

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Adolfo Díez-Pérez URFOA, IMIM (Institut Hospital del Mar d’Investigacions Mèdiques), Universitat Autònoma de Barcelona, Barcelona, Spain

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Susan M Webb Endocrinology/Medicine Department, Hospital Sant Pau, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER, Unidad 747), IIB-Sant Pau, ISCIII and Universitat Autònoma de Barcelona (UAB), Barcelona, Spain

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Background

Biochemical control of GH/IGF-I excess in acromegaly (ACRO) is associated with persistent impairment of trabecular microstructure leading to increased risk of vertebral fractures. Circulating miRNAs modulate the activity of osteoblasts and osteoclasts, and may be potential biomarkers of osteoporosis.

Aims

Identify differentially expressed miRNAs in the serum of patients with controlled ACRO vs controls and correlate miRNA levels with both biochemical and structural bone parameters.

Patients and methods

Twenty-seven patients with controlled ACRO (11 males, 16 females; mean age, 48 ± 5 years; BMI, 28 ± 4 kg/m2) and 27 age-, gender- and BMI-matched controls were recruited. Areal BMD at lumbar spine and femur, and trabecular bone score were assessed; volumetric BMD was measured by quantitative computed tomography QCT-Pro (Mindways). Twenty miRNAs, chosen by their putative role in bone, were quantified in serum using real-time qPCR.

Results

In ACRO patients, miR-103a-3p and miR-191-5p were found overexpressed, whereas miR-660-5p was underexpressed (P < 0.001). miR-103a-3p levels were negatively associated with both trabecular vBMD at trochanter and serum osteoprotegerin concentrations (P < 0.05) and positively with vitamin D concentrations (P < 0.01) and total cross-sectional area of the femoral neck (P < 0.05). miR-660-5p levels were correlated with both trabecular vBMD at trochanter and OPG concentrations (P < 0.05), but were negatively associated with vitamin D levels (P < 0.05). A negative correlation between miR-103-a-3p and miR-660-5p was found in both groups (P < 0.001).

Conclusions

Circulating miR-103a-3p and miR-660-5p are differentially expressed in controlled ACRO patients and associated with bone structural parameters. miRNAs may be one of the mechanisms involved in the pathogenesis of bone disease and could be used as biomarkers in ACRO patients.

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S Westra Department of Internal Medicine, Medical Centre Alkmaar, Alkmaar, the Netherlands

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Y H M Krul-Poel Department of Internal Medicine, Medical Centre Alkmaar, Alkmaar, the Netherlands

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H J van Wijland Department of General Practice, DIAZON, Alkmaar, the Netherlands

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M M ter Wee Department of Epidemiology and Biostatistics, VU Medical Centre, Amsterdam, the Netherlands

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F Stam Department of Internal Medicine, Medical Centre Alkmaar, Alkmaar, the Netherlands

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P Lips Department of Internal Medicine, Endocrine Section, VU Medical Centre, Amsterdam, the Netherlands

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F Pouwer Department of Medical and Clinical Psychology, Tilburg University, Tilburg, the Netherlands

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S Simsek Department of Internal Medicine, Medical Centre Alkmaar, Alkmaar, the Netherlands

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Objective

Increased levels of depressive symptoms, fatigue or pain (all dimensions of reduced health-related quality of life (HRQOL)) are common in people with type 2 diabetes mellitus (DM). Earlier studies have reported associations between low vitamin D status and fatigue and depressive symptoms. The aim of the present study was to examine the effects of vitamin D supplementation on dimensions of HRQOL in people with type 2 DM.

Design

Randomised, double-blind, placebo-controlled trial.

Methods

The effect of monthly cholecalciferol 50,000 IU vs placebo on HRQOL was assessed in 275 adults with type 2 DM derived from general practices. HRQOL at baseline and after six months using the Short Form 36 Health Survey (SF-36) was collected. Linear regression analyses were used to compare the change in HRQOL over time between the vitamin D and placebo group.

Results

187/275 (68%) completed baseline and follow-up SF-36 and were included in the analysis. Median serum 25-hydroxyvitamin D almost doubled in the intervention group compared to that in the placebo group (58.5–106.0 nmol/L vs 60.0–61.5 nmol/L, respectively). A small significant difference (adjusted B: −8.90; 95% CI: −17.16 to −0.65) between both groups was seen concerning the SF-36 domain role limitations due to physical problems in disadvantage of the vitamin D group.

Conclusions

Six months of vitamin D supplementation did not improve HRQOL in non-vitamin D-deficient people with type 2 DM managed on oral antidiabetic therapy.

Open access
Mirjam M Oosterwerff Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Rosa Meijnen Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Natasja M Van Schoor Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Dirk L Knol Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Mark H H Kramer Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Mireille N M Van Poppel Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Paul Lips Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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E Marelise W Eekhoff Departments of Internal Medicine, Epidemiology and Biostatistics, Public and Occupational Health, Endocrine Section

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Vitamin D deficiency is highly prevalent among non-western immigrants in The Netherlands and associated with poor physical performance. The aim of this study was to assess the effect of vitamin D supplementation on physical performance, exercise capacity, and daily physical activity in vitamin D-deficient, overweight non-western immigrants. A randomized double-blind, placebo-controlled trial was conducted to assess the effect of vitamin D on physical performance. A total of 130 participants were included. Eligibility criteria included overweight (BMI >27 kg/m2), 25-hydroxy vitamin D (25(OH)D) ≤50 nmol/l, and an age range of 20–65 years. The intervention group received 1200 IU vitamin D3 daily for 4 months; the control group received placebo. Both groups received 500 mg calcium daily. Outcome measures included physical performance (physical performance score), exercise capacity (a 6-min walk test (6-MWT)), and daily physical activity (questionnaire and accelerometer). There was no significant effect on physical performance, exercise capacity, or physical activity in the intention to treat analysis. In an explorative post hoc analysis restricted to participants reaching a serum 25(OH)D concentration of >60 nmol/l after intervention, there was an improvement of 19 m in the 6-MWT compared with the control group (P=0.053). Moderate dose vitamin D supplementation did not significantly improve physical performance, exercise capacity, or physical activity. However, when 25(OH)D concentrations reached >60 nmol/l after intervention, there was a borderline significant improvement in exercise capacity. Although the clinical relevance is not clear, this is a promising result, as all participants were overweight and did not improve their overall activity levels.

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Göran Oleröd Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden

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Lillemor Mattsson Hultén Department of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden

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Ola Hammarsten Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden

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Eva Klingberg Department of Rheumatology and Inflammation Research, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden

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Purpose

Serum 25-hydroxy vitamin D [25(OH)D] varies greatly with season at northern latitudes. The purpose of this study was to determine if the seasonal variations in serum total 25(OH)D are followed by a concomitant variation in free 25(OH)D or if the variation is damped by alterations in the binding capacity of DBP.

Methods

Serum was collected from 540 healthy blood donors (60% men; mean age 41 ± 13 years) during 12 months and analyzed for total 25(OH)D, directly measured free 25(OH)D, vitamin D-binding protein (DBP) and albumin. Calculated free 25(OH)D was estimated.

Results

The UV-B radiation during the sampling month was positively correlated with the serum levels of total 25(OH)D (r = 0.355, P < 0.001), directly measured free (r = 0.336, P < 0.001) and calculated free 25(OH)D (r = 0.275, P < 0.001), but not with DBP and albumin. The percentage of free 25(OH)D was higher during the winter months than that during the summer months (0.020 ± 0.005% vs 0.019 ± 0.004%; P = 0.007) and higher in participants with a serum 25(OH)D below 25 nmol/L than that in participants with a serum 25(OH)D above 75 nmol/L (0.031 ± 0.007% vs 0.017 ± 0.003%; P < 0.001). iPTH was correlated with directly measured free 25(OH)D (r = −0.226; P < 0.001), but only weakly with calculated free 25(OH)D (r = −0.095; P = 0.027).

Conclusions

Directly measured free serum 25(OH)D was highly correlated with total serum 25(OH)D and followed the same seasonal variation, whereas the serum concentrations of DBP and albumin were stable. The fluctuation in free 25(OH)D was only marginally damped with an increase in the percentage of free 25(OH)D during the winter months and in participants with vitamin D deficiency.

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Sharon A Huish University Hospitals of Coventry and Warwickshire NHS Trust, Coventry, UK
The University of Warwick, Coventry, UK
Royal Devon and Exeter NHS Foundation Trust, Exeter, UK

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Carl Jenkinson The University of Birmingham, Birmingham, UK

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Janet A Dunn The University of Warwick, Coventry, UK

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David J Meredith Royal Devon and Exeter NHS Foundation Trust, Exeter, UK

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Rosemary Bland The University of Warwick, Coventry, UK

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Martin Hewison The University of Birmingham, Birmingham, UK

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Low serum 1,25-dihydroxyvitamin D (1,25(OH)2D) in end-stage renal disease (ESRD) is considered a consequence of elevated fibroblast growth factor 23 (FGF23) and concomitant reduced activity of renal 1α-hydroxylase (CYP27B1). Current ESRD treatment strategies to increase serum calcium and suppress secondary hyperparathyroidism involve supplementation with vitamin D analogues that circumvent 1α-hydroxylase. This overlooks the potential importance of 25-hydroxyvitamin D (25(OH)D) deficiency as a contributor to low serum 1,25(OH)2D. We investigated the effects of vitamin D (cholecalciferol) supplementation (40,000 IU for 12 weeks and maintenance dose of 20,000 IU fortnightly), on multiple serum vitamin D metabolites (25(OH)D, 1,25(OH)2D3 and 24,25(OH)2D3) in 55 haemodialysis patients. Baseline and 12 month data were compared using related-samples Wilcoxon signed rank test. All patients remained on active vitamin D analogues as part of routine ESRD care. 1,25(OH)2D3 levels were low at baseline (normal range: 60–120 pmol/L). Cholecalciferol supplementation normalised both serum 25(OH)D and 1,25(OH)2D3. Median serum 25(OH)D increased from 35.1 nmol/L (IQR: 23.0–47.5 nmol/L) to 119.9 nmol/L (IQR: 99.5–143.3 nmol/L) (P < 0.001). Median serum 1,25(OH)2D3 and 24,25(OH)2D3 increased from 48.3 pmol/L (IQR: 35.9–57.9 pmol/L) and 3.8 nmol/L (IQR: 2.3–6.0 nmol/L) to 96.2 pmol/L (IQR: 77.1–130.6 pmol/L) and 12.3 nmol/L (IQR: 9–16.4 nmol/L), respectively (P < 0.001). A non-significant reduction in daily active vitamin D analogue dose occurred, 0.94 µmcg at baseline to 0.77 µmcg at 12 months (P = 0.73). The ability to synthesise 1,25(OH)2D3 in ESRD is maintained but is substrate dependent, and serum 25(OH)D was a limiting factor at baseline. Therefore, 1,25(OH)2D3 deficiency in ESRD is partly a consequence of 25(OH)D deficiency, rather than solely due to reduced 1α-hydroxylase activity as suggested by current treatment strategies.

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Stan Ursem Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, Vrije Universiteit Amsterdam, Endocrine Laboratory, Amsterdam, Netherlands

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Vito Francic Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Martin Keppel University Institute for Medical and Chemical Laboratory Diagnostics, Paracelsus Medical University, Salzburg, Austria

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Verena Schwetz Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Christian Trummer Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Marlene Pandis Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Felix Aberer Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Martin R Grübler Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Nicolas D Verheyen Division of Cardiology, Department of Internal Medicine, Medical University of Graz, Graz, Austria

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Winfried März Synlab Academy, Synlab Holding Germany GmbH, München, Germany

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Andreas Tomaschitz Specialist Clinic of Rehabilitation Bad Gleichenberg, Bad Gleichenberg, Austria

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Stefan Pilz Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Barbara Obermayer-Pietsch Division of Endocrinology and Diabetology, Department of Internal Medicine, Endocrinology Lab Platform, Medical University of Graz, Graz, Austria

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Annemieke C Heijboer Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, Vrije Universiteit Amsterdam, Endocrine Laboratory, Amsterdam, Netherlands
Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, University of Amsterdam, Endocrine Laboratory, Amsterdam, Netherlands

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Objective

PTH can be oxidised in vivo, rendering it biologically inactive. Non-oxidised PTH (n-oxPTH) may therefore give a better image of the hormonal status of the patient. While vitamin D supplementation decreases total PTH (tPTH) concentration, the effect on n-oxPTH concentration is unexplored. We investigated the effect of vitamin D on n-oxPTH concentration in comparison to tPTH and compared the correlations between parameters of calcium, bone and lipid metabolism with n-oxPTH and tPTH.

Methods

N-oxPTH was measured in 108 vitamin D-insufficient (25(OH)D <75 nmol/L) hypertensive patients, treated with vitamin D (2800 IE daily) or placebo for 8 weeks in the Styrian Vitamin D Hypertension Trial (NCT02136771). We calculated the treatment effect and performed correlation analyses of n-oxPTH and tPTH with parameters of calcium, bone and lipid metabolism and oxidative stress.

Results

After treatment, compared to placebo, 25(OH)D concentrations increased, tPTH decreased by 9% (P < 0.001), n-oxPTH by 7% (P = 0.025) and the ratio of n-oxPTH/tPTH increased (P = 0.027). Changes in phosphate and HDL concentration correlated with changes in n-oxPTH, but not tPTH.

Conclusions

tPTH and n-oxPTH decrease upon vitamin D supplementation. Our study suggests that vitamin D supplementation reduces the oxidation of PTH, as we observed a small but significant increase in the non-oxidised proportion of PTH upon treatment. In addition, we found that changes in phosphate and HDL concentration showed a relationship with changes in n-oxPTH, but not tPTH. This may be explained by the biological activity of n-oxPTH. Further research should be carried out to establish the clinical relevance of n-oxPTH.

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Ranganathan R Rao Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK

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Harpal S Randeva Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK

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Sailesh Sankaranarayanan Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK

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Murthy Narashima Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK

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Matthias Möhlig Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK

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Hisham Mehanna Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK

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Martin O Weickert Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK
Warwickshire Institute for the Study of Diabetes, Warwick Medical School, Department of Endocrinology, Institute of Head and Neck Studies and Education (InHANSE), Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK

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Introduction/background

Vitamin D deficiency further increases circulating parathyroid hormone (PTH) levels in patients with primary hyperparathyroidism (pHPT), with potential detrimental effects on bone mass.

Methods

This was an observational clinical study in consecutive conservatively treated postmenopausal women (n=40) with pHPT and coexistent 25-hydroxyvitamin D deficiency (25OHD ≤50 nmol/l (≤20 ng/ml)). Patients who showed an increase in serum 25OHD above the threshold of vitamin D deficiency (>50 nmol/l; n=28) using treatment with various commonly prescribed vitamin D preparations were, for the purposes of statistical analyses, allocated to the treatment group. Patients who were retrospectively identified as having received no treatment with vitamin D and/or remained vitamin D deficient were considered as non-responders/controls (n=12). Adjusted calcium (adjCa), PTH and 25OHD concentrations were monitored in all subjects up to 54 months (mean observation period of 18±2 months).

Results

Prolonged increased vitamin D intake, regardless of the source (serum 25OHD, increase from 32.2±1.7 nmol/l at baseline to 136.4±11.6 nmol/l, P<0.0001), significantly reduced serum PTH (13.3±1.1 vs 10.5±1.0 pmol/l, P=0.0001), with no adverse effects on adjCa levels (2.60±0.03 vs 2.60±0.02 mmol/l, P=0.77) and renal function tests (P>0.73). In contrast, serum PTH remained unchanged (15.8±2.6 vs 16.3±1.9 pmol/l, P=0.64) in patients who remained vitamin D deficient, with a significant difference between groups in changes of PTH (P=0.0003). Intrapartial correlation analyses showed an independent negative correlation of changes in 25OHD with PTH levels (r ic=−0.41, P=0.014).

Conclusions

Prolonged treatment with vitamin D in various commonly prescribed preparations appeared to be safe and significantly reduced PTH levels by 21%.

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