Vitamin D assays: past and present debates, difficulties, and developments

Target trial emulation of preconception serum vitamin D status on fertility outcomes: a couples-based approach

OBJECTIVE

To evaluate associations between preconception 25-hydroxyvitamin D (25(OH)D) levels and biomarkers in female and male partners on live birth (LB), pregnancy loss, and semen quality.

DESIGN

Secondary analysis using the folic acid and zinc supplementation trial of couples seeking infertility treatment at four US centers (2013-2017). A target trial emulation framework was applied to estimate associations. Couples were observed for 9 months or through pregnancy.

SETTING

Clinics that provide reproductive endocrinology and infertility care in the US.

PATIENT(S)

Couples seeking infertility treatment.

INTERVENTION(S)

Preconception concentrations of 25(OH)D (primary) and associated biomarkers: vitamin D binding protein, calcium, free vitamin D, bioavailable vitamin D.

MAIN OUTCOME MEASURE(S)

Live birth and pregnancy loss were ascertained via self-report and medical records. Semen quality was ascertained 6 months after enrollment. Log-binomial regression estimated risk ratios and 95% confidence intervals (CIs). Individual and joint models and effect measure modification by preconception body mass index were considered.

RESULT(S)

Among 2,370 couples, 19.5% of females and 29.9% of males were 25(OH)D deficient. Females with sufficient status had a 28%-higher likelihood of LB than deficient females (95% CI, 1.05-1.56). Female and male 25(OH)D status were associated with LB among those with normal body mass index (sufficient vs. deficient: female adjusted risk ratio [aRR], 1.39; 95% CI, 1.00-1.99; male aRR, 1.51; 95% CI, 1.01-2.25) and among obese female partners (sufficient vs. deficient: aRR, 1.33; 95% CI, 0.95-1.85). Couples whose both partners had higher 25(OH)D status had increased likelihood of LB (both not deficient vs. both deficient aRR, 1.26; 95% CI, 1.00-1.58). No associations were observed with pregnancy loss or semen quality. Similar results were found for all biomarkers except calcium.

CONCLUSION(S)

Preconception vitamin D status and bioavailability impact fertility among couples seeking infertility therapy, likely unrelated to semen quality. Body mass index stratified analyses demonstrated heterogeneous associations.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01857310.

No Evidence That Vitamin D Levels or Deficiency Are Associated with the Risk of Open-Angle Glaucoma in Individuals of European Ancestry: A Mendelian Randomisation Analysis

BACKGROUND

Glaucoma is the second leading cause of blindness worldwide, with intraocular pressure as the only known modifiable risk factor. Vitamin D has been proposed to influence intraocular pressure and decrease retinal ganglion cell degeneration. Based on these findings, vitamin D has been suggested to prevent or reduce the severity of primary open-angle glaucoma (POAG), which is the most common form.

METHODS

We applied two-sample Mendelian randomisation (MR) analyses to data from the SUNLIGHT consortium and the UK Biobank to assess the causal effect of vitamin D levels and vitamin D deficiency on primary open-angle glaucoma (POAG). MR analysis, including sensitivity tests using other GWAS summary statistics from FinnGen, was also performed. We also investigated the association between single nucleotide polymorphisms (SNPs) on genes involved in vitamin D metabolic pathways and POAG.

RESULTS

We found no statistical evidence that vitamin D levels (OR = 1.146, 95% CI 0.873 to 1.504, p = 0.326) or vitamin D deficiency (OR = 0.980 (95% CI 0.928 to 1.036, p = 0.471) causally affect the risk of developing POAG. Sensitivity analyses, including the use of a more relaxed p-value threshold, and use of winter-measured samples only, replication in the FinnGen dataset, and exploration of specific genetic markers also showed no evidence of association between SNPs for genes involved in key steps of vitamin D metabolism and POAG.

CONCLUSIONS

These results indicate that vitamin D may not be a significant factor in modifying POAG risk, challenging the hypothesis that vitamin D supplementation could be effective in reducing POAG risk. Further research should focus on identifying other potential risk factors for POAG prevention strategies.

Advances in biomedical applications of vitamin D for VDR targeted management of obesity and cancer

BACKGROUND

1,25(OH)2D3 is a fat-soluble vitamin, involved in regulating Ca2+ homeostasis in the body. Its storage in adipose tissue depends on the fat content of the body. Obesity is the result of abnormal lipid deposition due to the prolonged positive energy balance and increases the risk of several cancer types. Furthermore, it has been associated with vitamin D deficiency and defined as a low 25(OH)2D3 blood level. In addition, 1,25(OH)2D3 plays vital roles in Ca2+-Pi and glucose metabolism in the adipocytes of obese individuals and regulates the expressions of adipogenesis-associated genes in mature adipocytes.

SCOPE AND APPROACH

The present contribution focused on the VDR mediated mechanisms interconnecting the obese condition and cancer proliferation due to 1,25(OH)2D3-deficiency in humans. This contribution also summarizes the identification and development of molecular targets for VDR-targeted drug discovery.

KEY FINDINGS AND CONCLUSIONS

Several studies have revealed that cancer development in a background of 1,25(OH)2D3 deficient obesity involves the VDR gene. Moreover, 1,25(OH)2D3 is also known to influence several cellular processes, including differentiation, proliferation, and adhesion. The multifaceted physiology of obesity has improved our understanding of the cancer therapeutic targets. However, currently available anti-cancer drugs are notorious for their side effects, which have raised safety issues. Thus, there is interest in developing 1,25(OH)2D3-based therapies without any side effects.

Selective dual sensing strategy for free and vitamin D3 micelles in food samples based on S,N-GQDs photoinduced electron transfer

A reliable nanotechnological sensing strategy, based on an S,N-co-doped graphene quantum dot (GQD) platform, has been developed to distinctly detect two key variants of vitamin D3, specifically the free (VD3) and the nanoencapsulated form (VD3Ms). For this purpose, food-grade vitamin D3 micelles were self-assembled using a low-energy procedure (droplet size: 49.6 nm, polydispersity index: 0.34, ζ-potential: -33 mV, encapsulation efficiency: 90 %) with an innovative surfactant mixture (Tween 60 and quillaja saponin). Herein, four fluorescent nanoprobes were also synthesized and thoroughly characterized: S,N-co-doped GQDs, α-cyclodextrin-GQDs, β-cyclodextrin-GQDs, and γ-cyclodextrin-GQDs. The goal was to achieve a selective dual sensing strategy for free VD3 and VD3Ms by exploiting their distinctive quenching behaviors. Thus, the four nanosensors allowed the individual sensing of both targets to be performed (except α-CD-GQD for VD3Ms), but S,N-GQDs were finally selected due to selectivity and sensitivity (quantum yield, QY= 0.76) criteria. This choice led to a photoinduced electron transfer (PET) mechanism associated with static quenching, where differentiation was evidenced through a displayed 13-nm hypsochromic (blue) shift when interacting with VD3Ms. The reliability of this dual approach was demonstrated through an extensive evaluation of analytical performance characteristics. The feasibility and accuracy were proven in commercial food preparations and nutritional supplements containing declared nanoencapsulated and raw VD3, whose results were validated by a paired Student's t-test comparison with a UV-Vis method. To the best of our knowledge, this represents the first non-destructive analytical approach addressing the groundbreaking foodomic trend to distinctly detect different bioactive forms of vitamin D3, while also preserving their native nanostructures as a chemical challenge, thus providing reliable information about their final stability and bioavailability.

Association between serum vitamin D level and Graves' disease: a systematic review and meta-analysis

OBJECTIVE

This meta-analysis aims to analyze the relationship between serum vitamin D (VD) levels and Graves' disease (GD).

METHODS

We conducted a search for publications on VD and GD in the English language. Our search encompassed databases such as PubMed, Embase, Web of Science, and the Cochrane Library, covering publications available through August 2023. A meta-analysis was performed using Cochrane RevMan 5.4 software. The standardized mean difference (SMD) and 95% confidence interval (CI) were used for outcome calculation. We used R software to test for publication bias.

RESULTS

Twelve studies were selected, comprising 937 (22.4%) cases with GD and 3254 (77.6%) controls. The overall meta-analysis revealed that patients with GD are significantly more likely to have low VD levels (SMD = - 0.66; 95% CI: -1.05, - 0.27; p = 0.001) than those in the control group. Egger's test results indicated no publication bias (p = 0.0791). These studies exhibited a high degree of heterogeneity (chi-square = 205.86, p < 0.00001; I2 = 95%). Subgroup analysis was conducted based on assay method, geographic location, and mean age of the case group to explore the heterogeneity sources. Assay methods and geographic locations were identified as potential heterogeneity sources. Based on the mean age, there were no statistically significant differences found in the subgroup analysis of the included studies.

CONCLUSION

There is promising evidence that low serum VD levels may increase the risk of GD. Further rigorous and long-term trials are needed to explore the role of VD in the onset and treatment of GD.

Vitamin D: A Bridge between Kidney and Heart

Chronic kidney disease (CKD) and cardiovascular disease (CVD) are highly prevalent conditions, each significantly contributing to the global burden of morbidity and mortality. CVD and CKD share a great number of common risk factors, such as hypertension, diabetes, obesity, and smoking, among others. Their relationship extends beyond these factors, encompassing intricate interplay between the two systems. Within this complex network of pathophysiological processes, vitamin D has emerged as a potential linchpin, exerting influence over diverse physiological pathways implicated in both CKD and CVD. In recent years, scientific exploration has unveiled a close connection between these two prevalent conditions and vitamin D, a crucial hormone traditionally recognized for its role in bone health. This article aims to provide an extensive review of vitamin D's multifaceted and expanding actions concerning its involvement in CKD and CVD.

Is it Time to Migrate to Liquid Chromatography Automated Platforms in the Clinical Laboratory? A Brief Point of View

Liquid chromatography coupled to mass spectrometry already started to surpass the major drawbacks in terms of sensitivity, specificity and cross-reactivity that some analytical methods used in the clinical laboratory exhibit. This hyphenated technique is already preferred for specific applications while finding its own place in the clinical laboratory setting. However, large-scale usage, high-throughput analysis and lack of automation emerge as shortcomings that liquid chromatography coupled to mass spectrometry still has to overrun in order to be used on a larger scale in the clinical laboratory. The aim of this review article is to point out the present-day position of the liquid chromatography coupled to mass spectrometry technique while trying to understand how this analytical method relates to the basic working framework of the clinical laboratory. This paper offers insights about the main regulation and traceability criteria that this coupling method has to align and comply to, automation and standardization issues and finally the critical steps in sample preparation workflows all related to the high-throughput analysis framework. Further steps are to be made toward automation, speed and easy-to-use concept; however, the current technological and quality premises are favorable for chromatographic coupled to mass spectral methods.

Designing a label-free electrochemical aptasensor based on polypyrrole-l-cysteine-reduced graphene oxide nanocomposite for detection of 25-hydroxyvitamin D3

Reliable and precise quantification of 25-hydroxyvitamin D3 in clinical samples is vital because vitamin D3 deficiency lead to several disorders, such as mental illness, osteoporosis, and coronavirus disease. Herein, we report the fabrication of a novel electrochemical aptasensor using a nanocomposite, including reduced graphene oxide, pyrrole, and l-cysteine, for the sensitive detection of 25-hydroxyvitamin D3 . Subsequently, the aptamer of 25-hydroxyvitamin D3 was immobilized on the surface of the modified electrode. Differential pulse voltammetry signals were utilized for studying the binding and measurement of 25-hydroxyvitamin D3 based on the oxidation peak. Under the optimum conditions, the designed electrochemical aptasensor exhibited a linear detection range of 0.001-150 nM, with a limit of detection of 0.006 nM. Furthermore, the proposed aptasensor selectively detected 25-hydroxyvitamin D3 compared to other analogs. Moreover, this aptasensor was successfully applied for the detection of 25-hydroxyvitamin D3 in human serum samples, which were quantified by the enzyme-linked immunosorbent assay method. The acceptable recoveries of 82.67%-111.07% demonstrated that this proposed electrochemical aptasensor can be a promising alternative for clinical methods of vitamin D determination.

The Role of Vitamin D in Reducing the Risk of Metabolic Disturbances That Cause Cardiovascular Diseases

Among the most common problems facing public health today is a lack of vitamin D, which plays a role in the physiological processes of chronic illness conditions. Vitamin D deficiency in metabolic disorders has primary effects on osteoporosis, obesity, hypertension, diabetes, and cardiovascular disease (CVD). Vitamin D acts as a "co-hormone" in the various tissues of the body, and it has been found that vitamin D receptors (VDR) are present on all cell types, suggesting that vitamin D has a wide range of effects on most cells. Recently, there has been a surge in interest in assessing its roles. Vitamin D insufficiency increases the risk of diabetes because it lowers insulin sensitivity, and also raises the risk of obesity and CVD because of its effect on the body's lipid profile, particularly in terms of the prevalence of dangerously high levels of low-density lipoproteins (LDL). Furthermore, vitamin D insufficiency is often related to CVD and connected risk factors, highlighting the need to know vitamin D's functions in relation to metabolic syndrome and related processes. Through looking at previous studies, this paper explains why vitamin D is important, how deficiency is related to risk factors for metabolic syndrome through different mechanisms, and how deficiency affects CVD.

Vitamin D Determinants, Status, and Antioxidant/Anti-inflammatory-Related Effects in Cardiovascular Risk and Disease: Not the Last Word in the Controversy

Beyond its key role in calcium homeostasis, vitamin D has been found to significantly affect the cardiovascular (CV) system. In fact, low vitamin D levels have been associated with increased CV risk, as well as increased CV morbidity and mortality. The majority of effects of this molecule are related directly or indirectly to its antioxidative and anti-inflammatory properties. Generally, vitamin D insufficiency is considered for 25-hydroxyvitamin D (25(OH)D) levels between 21-29 ng/mL (corresponding to 52.5-72.5 nmol/L), deficiency as 25(OH)D levels less than 20 ng/mL (<50 nmol/L), and extreme deficiency as 25(OH)D less than 10 ng/mL (<25 nmol/L). However, the definition of an optimal vitamin D status, as defined by 25(OH)D, remains controversial for many extra-bone conditions, including CV disease. In this review, confounding factors affecting the 25(OH)D measurement and status will be discussed. In particular, available evidence on the mechanism and role of vitamin D in relation to CV risk and disease through its antioxidant effect will be reported, also facing the aspect regarding the debate on the minimum blood 25(OH)D level required to ensure optimal CV health.

3' Untranslated Region Structural Elements in CYP24A1 Are Associated With Infantile Hypercalcemia Type 1

Loss-of-function mutations in the CYP24A1 protein-coding region causing reduced 25 hydroxyvitamin D (25OHD) and 1,25 dihydroxyvitamin D (1,25(OH)₂ D) catabolism have been observed in some cases of infantile hypercalcemia type 1 (HCINF1), which can manifest as nephrocalcinosis, hypercalcemia and adult-onset hypercalciuria, and renal stone formation. Some cases present with apparent CYP24A1 phenotypes but do not exhibit pathogenic mutations. Here, we assessed the molecular mechanisms driving apparent HCINF1 where there was a lack of CYP24A1 mutation. We obtained blood samples from 47 patients with either a single abnormality of no obvious cause or a combination of hypercalcemia, hypercalciuria, and nephrolithiasis as part of our metabolic and stone clinics. We used liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine serum vitamin D metabolites and direct sequencing to confirm CYP24A1 genotype. Six patients presented with profiles characteristic of altered CYP24A1 function but lacked protein-coding mutations in CYP24A1. Analysis upstream and downstream of the coding sequence showed single nucleotide variants (SNVs) in the CYP24A1 3' untranslated region (UTR). Bioinformatics approaches revealed that these 3' UTR abnormalities did not result in microRNA silencing but altered the CYP24A1 messenger RNA (mRNA) secondary structure, which negatively impacted translation. Our experiments showed that mRNA misfolding driven by these 3' UTR sequence-dependent structural elements was associated with normal 25OHD but abnormal 1,25(OH)₂ D catabolism. Using CRISPR-Cas9 gene editing, we developed an in vitro mutant model for future CYP24A1 studies. Our results form a basis for future studies investigating structure-function relationships and novel CYP24A1 mutations producing a semifunctional protein. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Vitamin D metabolites and analytical challenges

Vitamin D is an essential micronutrient for bone health and the general cellular functions of the body. Its insufficiency/deficiency leads to the pathophysiology of disorders like diabetes, cancer, autoimmune, neurodegenerative, and cardiovascular diseases. Clinical interest in Vitamin D metabolites and their role in various medical disorders have contributed to an increase in laboratory demands for vitamin D measurements. For clinical and research laboratories worldwide, analysis of vitamin D and associated metabolites is a significant problem. The best way for determining vitamin D levels is constantly being debated. Various methods such as immunoassays and chromatographic techniques are available for determining vitamin D levels. Additionally, biosensors have recently been considered promising options for routine vitamin D analysis. The existing methods and other developments in the measurement of vitamin D metabolites and associated analytical challenges are discussed in this review.

Comparison of the Serum Total 25-Hydroxyvitamin D Concentrations Using Chemiluminescent Immunoassay and Liquid Chromatography-Tandem Mass Spectrometry in Children

We aimed to assess the difference and agreement between the CL-series Vitamin D Total assay (Mindray), which was a kind of chemiluminescent immunoassay (CLIA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the measurement of serum 25-hydroxyvitamin D [25(OH)D] concentrations in children. We compared the 25(OH)D concentrations of 92 children using the CLIA and LC-MS/MS. Paired samples t-test was used to compare the two groups. Linear regression was used to show the correlation between CLIA and LC-MS/MS. The difference and bias between 2 methods were revealed in Bland-Altman plot. Agreement in classification of deficiency between CLIA and LC-MS/MS was assessed using Cohen's Kappa. p value<0.05 was considered statistically significant. Using Shapiro-Wilk Test to assess whether the data follows a normal distribution. Using 95% children's serum 25(OH)D concentrations by LC-MS/MS as the reference interval. The regression equation was CLIA=1.185×LC-MS/MS-3.328. The fitness adjusted r² was 0.589. The CLIA showed positive bias compared to LC-MS/MS, p<0.05, bias=(1.94±16.56) ng/mL. Cohen's Kappa=0.53, p<0.001. The agreement of 2 methods in diagnosing "deficiency" was good. According to Shapiro-Wilk Test, the data followed a normal distribution (W=0.99). The reference interval of children's serum 25(OH)D concentrations by LC-MS/MS was 11.35-44.57 ng/mL. In measuring 25(OH)D concentration of children, CLIA represented higher levels than LC-MS/MS. The two methods were consistent in diagnosing vitamin D deficiency. The reference interval of children's serum 25(OH)D concentrations by LC-MS/MS was 11.35-44.57 ng/mL in our area in summer.

A comprehensive look into the association of vitamin D levels and vitamin D receptor gene polymorphism with obesity in children

Childhood obesity accounts for several psychosocial and clinical consequences. Psychosocial consequences include lower self-esteem, social isolation, poor academic achievement, peer problems, and depression, whereas clinical consequences are cardiovascular diseases, type 2 diabetes, dyslipidemia, cancer, autoimmune diseases, girls early polycystic ovarian syndrome (PCOS), asthma, bone deformities, etc. A growing number of studies have uncovered the association of childhood obesity and its consequences with vitamin-D (vit-D) deficiency and vitamin-D receptor (VDR) gene polymorphisms such as single nucleotide polymorphisms (SNPs), e.g., TaqI, BsmI, ApaI, FokI, and Cdx2. Considering the impact of vit-D deficiency and VDR gene polymorphisms, identifying associated factors and risk groups linked to lower serum vit-D levels and prevention of obesity-related syndromes in children is of utmost importance. Previously published review articles mainly focused on the association of vit-D deficiency with obesity or other non-communicable diseases in children. The nature of the correlation between vit-D deficiency and VDR gene polymorphisms with obesity in children is yet to be clarified. Therefore, this review attempts to delineate the association of obesity with these two factors by identifying the molecular mechanism of the relationship.

Testing for Vitamin D in High-Risk COPD in Outpatient Clinics in Spain: A Cross-Sectional Analysis of the VITADEPOC Study

Background: Vitamin D deficiency has been associated with an accelerated deterioration in lung function and increased exacerbations in chronic obstructive pulmonary disease (COPD). 25(OH) vitamin D levels have been indicated as a potentially useful marker for adverse results related to COPD. Methods: VITADEPOC is a cross-sectional clinical study recruiting consecutive patients with high-risk COPD. The objective of our study was to investigate vitamin D determination frequency in patients with high-risk COPD in clinical practice at outpatient clinics in Spain and to describe the factors associated with vitamin D testing. We also aimed to determine the frequency of vitamin D deficiency in these patients. Results: Only 51 (44%) patients underwent vitamin D determination and 33 (28.4%) had received vitamin D supplements in clinical practice. The patients who underwent testing for vitamin D in clinical practice were more often women (58.8% vs. 26.2%, p < 0.001) with comorbidities such as osteoporosis (19.6% vs. 6.2%, p < 0.001) or chronic renal failure (7.8% vs. 0%, p < 0.001) and with exacerbator phenotype (55% vs. 32.3%, p = 0.015). A total of 63 (54.3%) patients had serum vitamin D levels <20 ng/mL at the inclusion visit. Of these, 29 (46%) had serum vitamin D levels <12 ng/mL (severe deficiency). Having a history of inhaled corticosteroids (OR 3.210, p < 0.016), being treated with a cycle of systemic corticosteroids (OR 2.149, p < 0.002), and having a lower physical activity level (OR 3.840, p < 0.004) showed a statistically significant positive association with vitamin D deficiency. Conclusion: The testing of vitamin D levels in patients with high-risk COPD treated at outpatient respiratory clinics in Spain is infrequent. However, when tested, a severe deficiency is detected in one in four patients. Efforts to optimize case detection in COPD are needed.

Time out: should vitamin D dosing be based on patient's body mass index (BMI): a prospective controlled study

The recommended daily dose of vitamin D is 2000 IU was found to be insufficient in many patients. The objective of the present study is to find whether the daily dose of vitamin D should be based on BMI. Two hundred and thirty patients with an established vitamin D deficiency (serum level of 25 Hydroxy vitamin D3 (25OHD3) of ≤20 ng/ml) and patients with BMI ≥30 kg/m2 were included in the study. Demographic data, comorbidities and BMI were recorded. Pre-treatment and post-treatment serum 25OHD3, calcium, phosphorus and parathyroid hormone (PTH) were tested at 0-, 3- and 6-month periods. Patients were treated with a standard dose of 50 000 IU of vitamin D weekly and 600/1200 mg of calcium a day. Once their level of 25OHD3 reached ≥30 ng/ml, patients were randomised into two groups. Group A received a standard recommended maintenance dose of 2000 IU daily and Group B patients received 125 IU/kg/m2 of vitamin D3. The data were entered in the database and analysed. The mean age of Group A was 50⋅74 ± 7⋅64 years compared to 52⋅32 ± 7⋅21 years in Group B. In both groups, pre-treatment vitamin D level was ≤15 ng/ml and increased to 34⋅6 ± 2⋅6 and 33⋅7 ± 2⋅4 ng/ml at the end of 3 months treatment with a dose 50 000 IU of vitamin D3 and calcium 600/1200 mg once a day for group A and group B, respectively. At 6 months, patients in Group A 25OHD3 level was 22⋅8 ± 3⋅80 and in Group B was 34⋅0 ± 1⋅85 ng/ml (P < 0⋅001). This preliminary study suggests that obese patients need higher dosage of vitamin D than the recommended dose. It is prudent that the dosage should be based on the BMI to maintain normal levels for a healthy musculoskeletal system.

The Effect of Maternal Vitamin D Supplementation on Vitamin D Status of Exclusively Breast Feeding Mothers and Their Nursing Infants: A Systematic Review and Meta-analysis of Randomized Clinical Trials

The optimal vitamin D supplementation plan during lactation is unclear. We investigated the effect of maternal vitamin D supplementation on mother-infant dyads' vitamin D status during lactation. All controlled trials that compared vitamin D supplements to placebo or low doses of vitamin D in breastfeeding mothers were included. Pooled effect size and the associated 95% confidence interval (CI) for each outcome were estimated using random-effects models. A one-stage random-effect dose-response model was used to estimate the dose-response relation across different vitamin D dosages and serum 25-hydroxy vitamin D (25(OH)D) concentrations. We identified 19 clinical trials with 27 separate comparison groups (n = 3337 breastfeeding mothers). Maternal vitamin D supplement dosages were associated with circulating 25(OH)D concentrations in breastfeeding women in a non-linear fashion. Supplementation with 1000 IU of vitamin D/day increased serum 25(OH)D concentrations by 7.8 ng/mL while there was a lower increase in concentrations at vitamin D doses of >2000 IU/day (3.07 and 2.05 ng/mL increases between 2000 to 3000 and 3000 to 4000 IU/day, respectively). A linear relationship was observed between maternal vitamin D supplementation dosage and the infants' circulating 25(OH)D concentrations. Each additional 1000 IU of maternal vitamin D intake was accompanied by a 2.7 ng/mL increase in serum 25(OH)D concentration in their nursing infants. The subgroup analysis showed that maternal vitamin D supplementation was accompanied by a statistically significant increase in infants' 25(OH)D concentration in the trials with a duration of >20 weeks, vitamin D supplementation >1000 IU/day, East Indian participants, maternal BMI <25 kg/m2, and studies with an overall low risk of bias. Long-term maternal supplementation with vitamin D at a high dose (>6000 IU/day) effectively corrected vitamin D deficiency in both mothers and infants. Nevertheless, infants with 25(OH)D concentrations over 20 ng/mL may require a relatively low maternal dose to maintain vitamin D sufficiency.

STATEMENT OF SIGNIFICANCE

This study is the first dose-response analysis on the relation between circulating 25-hydroxy vitamin D (25(OH)D) and maternal vitamin D supplementation in mother-infant dyads. We also considered factors such as study design and population characteristics that may affect the outcomes of a given vitamin D trial that have been overlooked in previous reviews.

Evaluation of the 25-hydroxy vitamin D assay on a fully automated liquid chromatography mass spectrometry system, the Thermo Scientific Cascadion SM Clinical Analyzer with the Cascadion 25-hydroxy vitamin D assay in a routine clinical laboratory

Background Liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers advantages over immunoassay due to its increased specificity and ability to multiplex metabolites within a single run. Wide scale adoption of LC-MS/MS in routine clinical laboratories is restricted in part due to the high level of technical expertise required. The Thermo Scientific™ Cascadion™ SM Clinical Analyzer is the first fully automated, random access clinical analyser that utilises LC-MS/MS technology. We report an analytical validation of the 25-hydroxy vitamin D2 and D3 assays on the Cascadion Analyzer and an assessment of its performance within a routine clinical laboratory. Methods Analyser usability was assessed by staff with no previous experience of LC-MS/MS. An analytical validation included analysis of 154 patient samples on two different Cascadion Analyzers and a four-way method comparison of 146 patient samples on Roche and Siemens immunoassays and an in-house LC-MS/MS method. Accuracy was assessed using external quality assurance and reference materials. Seven third party IQC materials were tested on Cascadion. Results Cascadion proved easy to use by scientific and non-scientific staff. The assay passed all validation criteria. Excellent agreement was demonstrated between two different Cascadions (y = 0.97x + 3.9 nmol/L, r2 > 0.99). A method comparison demonstrated no significant difference (p > 0.05) between the Cascadion and the Roche immunoassay. A significant difference (p < 0.0001) was observed between the Cascadion and an LC-MS/MS and Siemens methods. Results obtained from EQA and reference material showed a mean bias of +3.09% and all samples were within ±10% of assigned concentrations. All third party IQC samples tested were compatible for use with Cascadion. Conclusions The Cascadion Analyzer is a fully automated LC-MS/MS system that requires no prior LC-MS/MS expertise. The vitamin D assays demonstrated excellent performance with high levels of accuracy.

Simultaneous measurement of 13 circulating vitamin D3 and D2 mono and dihydroxy metabolites using liquid chromatography mass spectrometry

Objectives

Clinical evaluation of vitamin D status is conventionally performed by measuring serum levels of a single vitamin D metabolite, 25-hydroxyvitamin D predominantly by immunoassay methodology. However, this neglects the complex metabolic pathways involved in vitamin D bioactivity, including two canonical forms D3 and D2, bioactive 1,25-dihydroxy metabolites and inactive 24-hydroxy and other metabolites.

Methods

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) can measure multiple analytes in a sample during a single run with high sensitivity and reference level specificity. We therefore aimed to develop and validate a LC-MS/MS method to measure simultaneously 13 circulating vitamin D metabolites and apply it to 103 human serum samples.

Results

The LC-MS/MS method using a Cookson-type derivatization reagent phenyl-1,2,4-triazoline-3,5-dione (PTAD) quantifies 13 vitamin D metabolites, including mono and dihydroxy-metabolites, as well as CYP11A1-derived D3 and D2 metabolites in a single run. The lower limit of quantitation was 12.5 pg/mL for 1,25(OH)₂D3 with accuracy verified by analysis of National Institute of Standards and Technology (NIST) 972a standards. Quantification of seven metabolites (25(OH)D3, 25(OH)D2, 3-epi-25(OH)D3, 20(OH)D3, 24,25(OH)₂D3, 1,25(OH)₂D3 and 1,20S(OH)₂D3) was consistently achieved in human serum samples.

Conclusions

This profiling method can provide new insight into circulating vitamin D metabolite pathways forming the basis for improved understanding of the role of vitamin D in health and disease.

Early-onset climacterium is not associated with impaired vitamin D status: a population-based study

OBJECTIVE

To investigate vitamin D status in women with the onset of the climacteric phase by age 46 as both early menopause and inadequate vitamin D status may increase the risk of adverse health outcomes.

METHODS

A cross-sectional study included 2,544, 46-year-old women from a birth cohort. Women were divided into the following two groups according to their menstrual history and follicle-stimulating hormone (FSH) concentration: 1) climacteric (FSH ≥25 IU/L and amenorrhea ≥4 mo, n = 351) and 2) preclimacteric women (FSH <25 IU/L and having regular/irregular menstrual cycles, n = 2,193). Serum 25-hydroxyvitamin D (25(OH)D) concentrations were compared between the groups. A linear regression model was performed to investigate which factors are associated with 25(OH)D status.

RESULTS

Mean serum 25(OH)D concentrations were higher in climacteric compared with preclimacteric women (68.1 ± 19.8 nmol/L vs 65.2 ± 19.3 nmol/L, P = 0.01). However, in the linear regression model, climacteric status was not associated with 25(OH)D status (multivariable adjusted mean difference 4.5 nmol/L, 95% confidence interval -1.4 to 10.4, P = 0.137). A total of 76 of the climacteric women were using systemic estrogen hormone therapy (HT). In a subanalysis, including only climacteric women, the use of HT was associated with higher 25(OH)D status (multivariable adjusted mean difference 5.9 nmol/L, 95% confidence interval 1.3-10.5, P = 0.013).

CONCLUSIONS

The onset of the climacteric phase by age 46 was not associated with inadequate 25(OH)D concentrations, whereas HT use was associated with higher 25(OH)D status in women with early-onset climacterium.

Vitamin D Sources, Metabolism, and Deficiency: Available Compounds and Guidelines for Its Treatment

Studies on vitamin/hormone D deficiency have received a vast amount of attention in recent years, particularly concerning recommendations, guidelines, and treatments. Moreover, vitamin D’s role as a hormone has been confirmed in various enzymatic, metabolic, physiological, and pathophysiological processes related to many organs and systems in the human body. This growing interest is mostly due to the evidence that modest-to-severe vitamin D deficiency is widely prevalent around the world. There is broad agreement that optimal vitamin D status is necessary for bones, muscles, and one’s general health, as well as for the efficacy of antiresorptive and anabolic bone-forming treatments. Food supplementation with vitamin D, or the use of vitamin D supplements, are current strategies to improve vitamin D levels and treat deficiency. This article reviews consolidated and emerging concepts about vitamin D/hormone D metabolism, food sources, deficiency, as well as the different vitamin D supplements available, and current recommendations on the proper use of these compounds.

Physical Determinants of Vitamin D Photosynthesis: A Review

Vitamin D synthesis by exposure of skin to solar ultraviolet radiation (UVR) provides the majority of this hormone that is essential for bone development and maintenance but may be important for many other health outcomes. This process, which is the only well-established benefit of solar UVR exposure, depends on many factors including genetics, age, health, and behavior. However, the most important factor is the quantity and quality of UVR reaching the skin. Vitamin D synthesis specifically requires ultraviolet B (UVB) radiation that is the minority component (<5%) of solar UVR. This waveband is also the most important for the adverse effects of solar exposure. The most obvious of which is sunburn (erythema), but UVB is also the main cause of DNA damage to the skin that is a prerequisite for most skin cancers. UVB at the Earth's surface depends on many physical and temporal factors such as latitude, altitude, season, and weather. Personal, cultural, and behavioral factors are also important. These include skin melanin, clothing, body surface area exposed, holiday habits, and sunscreen use. There is considerable disagreement in the literature about the role of some of these factors, possibly because some studies have been done by researchers with little understanding of photobiology. It can be argued that vitamin D supplementation obviates the need for solar exposure, but many studies have shown little benefit from this approach for a wide range of health outcomes. There is also increasing evidence that such exposure offers health benefits independently of vitamin D: the most important of which is blood-pressure reduction. In any case, public health advice must optimize risk versus benefit for solar exposure. It is fortunate that the individual UVB doses necessary for maintaining optimal vitamin D status are lower than those for sunburn, irrespective of skin melanin. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

No evidence that vitamin D is able to prevent or affect the severity of COVID-19 in individuals with European ancestry: a Mendelian randomisation study of open data

BACKGROUND

Upper respiratory tract infections are reportedly more frequent and more severe in individuals with lower vitamin D levels. Based on these findings, it has been suggested that vitamin D can prevent or reduce the severity of COVID-19.

METHODS

We used two-sample Mendelian randomisation (MR) to assess the causal effect of vitamin D levels on SARS-CoV-2 infection risk and COVID-19 severity using publicly available data. We also carried out a genome-wide association analysis (GWA) of vitamin D deficiency in the UK Biobank (UKB) and used these results and two-sample MR to assess the causal effect of vitamin D deficiency on SARS-CoV-2 infection risk and COVID-19 severity.

RESULTS

We found no evidence that vitamin D levels causally affect the risk of SARS-CoV-2 infection (ln(OR)=0.17 (95% CI -0.22 to 0.57, p=0.39)) nor did we find evidence that vitamin D levels causally affect COVID-19 severity (ln(OR)=0.36 (95% CI -0.89 to 1.61, p=0.57)). Based on our GWA analysis, we found that 17 independent variants are associated with vitamin D deficiency in the UKB. Using these variants as instruments for our two-sample MR analyses, we found no evidence that vitamin D deficiency causally affects the risk of SARS-CoV-2 infection (ln(OR)=-0.04 (95% CI -0.1 to 0.03, p=0.25)) nor did we find evidence that vitamin D deficiency causally affects COVID-19 severity (ln(OR)=-0.24 (95% CI -0.55 to 0.08, p=0.14)).

CONCLUSIONS

In conclusion, we found no evidence that vitamin D is protective against SARS-CoV-2 infection or COVID-19 severity. Our data support the recent statement by the National Institute for Health and Care Excellence that the use of vitamin D supplementation to mitigate COVID-19 is not supported by the available data.

Population vitamin D supplementation in UK adults: too much of nothing?

Topics for DTB review articles are selected by DTB's editorial board to provide concise overviews of medicines and other treatments to help patients get the best care. Articles include a summary of key points and a brief overview for patients. Articles may also have a series of multiple choice CME questions.

Atherosclerosis in SLE: a potential role for serum parathormone levels

Objective

A link between bone metabolism and cardiovascular (CV) disease has been suggested mainly in the general population. In the current study we explored whether altered bone metabolism influence CV risk in patients with SLE.

Methods

In 138 consecutive patients with SLE, atherosclerosis was assessed by the presence of plaque and/or arterial wall thickening in carotid/femoral arteries by ultrasound. Bone mineral density (BMD) levels and hip/spinal cord fractures together with classical CV disease and osteoporosis risk factors including serum 25(OH) vitamin D₃ and parathormone (PTH) levels were recorded in all patients. Serum osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-Β ligand were quantitated by commercial ELISA. Statistical analysis included both univariate and multivariate models.

Results

Abnormal PTH serum concentrations (>65 pg/mL)—but not 25(OH) vitamin D₃ serum levels—were identified as a risk factor for both plaque formation and arterial wall thickening in patients with SLE (ORs (95% CIs): 8.2 (1.8 to 37.4) and 3.9 (1.3 to 11.8), respectively). This association remained significant following adjustment for vitamin D₃ levels and classical CV risk factors. Moreover, an independent association between osteoporosis with plaque formation and arterial wall thickening was detected following adjustment for total steroid dose, premature menopause and disease duration (ORs (95% CIs): 5.3 (1.1 to 26.2) and 3.5 (1.1 to 11.4), respectively). An inverse correlation between femoral neck BMD values and intima–medial thickness scores was also observed (r: −0.42, p=0.008).

Conclusions

These findings further strengthen the concept of shared pathophysiological mechanisms between atherogenesis and altered bone metabolism in autoimmune populations, revealing heightened PTH levels as a potential marker for atherosclerosis among patients with SLE.

Correlation of low serum vitamin-D with uterine leiomyoma: a systematic review and meta-analysis

BACKGROUND

There is a growing body of evidence on low serum vitamin-D levels and the risk of uterine leiomyomas (UL). Therefore, this systematic review and meta-analysis was conducted to investigate the association between serum vitamin D levels and UL occurrence.

METHODS

Searches were systematically conducted of the electronic databases PubMed, Scopus, EMBASE, Web of Science (ISI), Cochrane library, Ovid, and Google Scholar to identify relevant studies from inception until February 6, 2020. Heterogeneity across the included studies was examined using Cochran's Q and I-square (I²). Data was pooled using random effects modeling and expressed as standardized mean differences (SMDs).

RESULTS

Nine eligible studies with a total of 1730 participants (835 patients with UL and 895 controls) were included in the current meta-analysis. Pooled results with random effects modeling indicated that serum vitamin D levels were significantly lower in patients with UL than in the control group (n = 9, SMD = - 0.67; 95% CI, - 0.98, - 0.35, p < 0.001; I² = 89.3%, p < 0.001). Based on the findings of subgroup analyses, it was found that the SMD values across the included studies from Asia (n = 4, SMD = - 1.20; 95% CI, - 1.45, - 0.96, p < 0.001; I² = 30.6%, p = 0.229) were lower than those from Europe (n = 3, SMD = - 0.34; 95% CI, - 0.49, - 0.18, p < 0.001; I² = 0.0%, p = 0.602) and Africa (n = 2, SMD = - 0.13; 95% CI, - 0.29, 0.04, p = 0.128; I² = 0.0%, p = 0.417), although the difference was not significant in Africa. Publication year was also found to be a potential contributor's variable in the pooled SMD using the meta-regression method (t = - 3.00, p = 0.02).

CONCLUSIONS

To the best of our knowledge, the current meta-analysis showed for the first time that serum vitamin D levels were significantly lower in women with UL in selected populations.

The Role of Interferences in the Increasing Incidence of Vitamin D Deficiency

OBJECTIVE

Lipemia is one of the causes of interference in immunoassay and LC-MS/MS methods. Increased prevalence of vitamin D deficiency in the US, where obesity is gradually increasing, raises the suspicion that high levels of fat diet and blood lipid levels interfere with vitamin D measurement results. The focus of this study was to investigate the effect of blood lipid profiles on vitamin D results and prevent the matrix effect.

MATERIAL AND METHODS

In this study, 25OH vitamin D3 (25OHD3) levels of 100 samples consecutively accepted to biochemistry laboratory regardless of age and sex were measured by the LC-MS/MS method, and each sample was restudied after 1/10 dilution. After dilution restudy, two groups were obtained-group 1 (results deviating below 20%) and group 2 (results deviating above 20%)-and the difference between the groups was investigated. There were 79 patients in group 1 and 21 patients in group 2. In our study, lipid profiles (triglyceride, total cholesterol, HDL, LDL) from the same samples of consecutive vitamin D patients were studied.

RESULTS

It was observed that the triglyceride, total cholesterol HDL, LDL, and 25OHD3 measurements of group 1 and group 2 were similar (p > 0.05). While the mean vitamin D value in the second group was 9.94 ± 7.85, the mean vitamin D value after dilution was measured as 39.23 ± 18.13 and was statistically significant. 25OHD3 concentrations of 21 patients out of 100 were found to be falsely low. Measurements were repeated to confirm the results.

CONCLUSION

The matrix effect caused by exogenous and endogenous interferences in the blood could be a hidden factor increasing the prevalence of vitamin D deficiency by causing falsely low 25OHD3 values. Suspicious results should be remeasured by a dilution study.

Vitamin D Measurement, the Debates Continue, New Analytes Have Emerged, Developments Have Variable Outcomes

The demand for measurement of vitamin D metabolites for clinical diagnosis and to advance our understanding of the role of vitamin D in human health has significantly increased in the last decade. New developments in technologies employed have enabled the separation and quantification of additional metabolites and interferences. Also, developments of immunoassays have changed the landscape. Programmes and materials for assay standardisation, harmonisation and the expansion of the vitamin D external quality assurance scheme (DEQAS) with the provision of target values as measured by a reference measurement procedure have improved standardisation, quality assurance and comparability of measurements. In this article, we describe developments in the measurement of the commonly analysed vitamin D metabolites in clinical and research practice. We describe current analytical approaches, discuss differences between assays, their origin, and how these may be influenced by physiological and experimental conditions. The value of measuring metabolites beyond 25 hydroxyvitamin D (25(OH)D), the marker of vitamin D status, in routine clinical practice is not yet confirmed. Here we provide an overview of the value and application of the measurement of 1,25 dihydroxyvitamin D, 24,25 dihydroxyvitamin D and free 25OHD in the diagnosis of patients with abnormalities in vitamin D metabolism and for research purposes.

Vitamin D supplementation has no effects on progression of motor dysfunction in amyotrophic lateral sclerosis (ALS)

OBJECTIVES

To investigate the effects of cholecalciferol supplementation on the progression of motor disability in a cohort of amyotrophic lateral sclerosis (ALS) patients with low blood 25-hydroxyvitamin D3 [25(OH)D] levels, on the basis of the hypothesis of potential neuroprotective effects of vitamin D supplementation.

METHODS

Forty-eight ALS patients, 34 with deficient (<20 ng/mL) and 14 with insufficient (20-29 ng/mL) serum levels of 25(OH)D, were randomized and treated by 3 different doses of cholecalciferol [50.000, 75.000 and 100.000 international units (IU) /month] and evaluated after 6-months. Assessment of motor dysfunction at baseline and after 6 months included ALS Functional Rating Scale-Revised (ALFRS-R) and upper motor neuron (UMN) scores and blood samples for 25(OH)D levels.

RESULTS

Clinical data of 33 patients were available after 6 months. Analysis of Covariance (ANCOVA), with pre-treatment measurements included as covariate, did not show statistically significant differences in the ALSFRS-R (p > 0.05) and UMN (p > 0.05) among the patient groups who underwent 3 different doses of cholecalciferol. Conversely, the treatment with 75.000 IU/month or 100.000 IU/month induced a significant increase in serum levels of 25(OH)D in comparison with the supplementation with 50.000 IU/month; no significant differences were found between 75.000 IU/month and 100.000 IU/month.

CONCLUSIONS

Our findings highlighted that 6-month supplementation of vitamin D in ALS patients had no significant effects on motor dysfunction. However, it is recommended to prevent medical complications of vitamin D deficiency in ALS patients as well as in other populations of neurodegenerative patients, characterized by low mobility and decreased sun exposure.

Simultaneous profiling of vitamin D metabolites in serum by supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS)

Simultaneous profiling of serum vitamin D (VD) metabolites with similar structures is a big challenge. Thus, we developed and validated a SFC-MS/MS method, which is capable of eluting hydrophobic molecules, for quantification of VD₂/VD₃, 25-OH VD₂/VD₃, 3-epi-25-OH VD₂/VD₃, 1,25-(OH)₂ VD₂/VD₃ and 24,25-(OH)₂ VD₂/VD₃. VD metabolites were extracted from human serum using acetonitrile solvent. Column stationary phase, elution gradients, flow rate, column temperature, ion-source type and buffer system in post-column make-up solvent were optimized. Baseline separation of 10 VD metabolites can be achieved using PFP column within 10 min; and detection performed under positive electrospray ionization mode allowed quantification of VD metabolites in serum matrix with a limit of quantification (LOQ) varrying from 0.071 to 0.704 ng/mL. The accuracy was controlled with relative bias lower than 5.5% for QC and NIST samples. The developed method showed excellent intra-assay (0.52-7.93% RSD) and inter-assay (1.35-9.04% RSD) precision. The methodology shows enhanced efficiency and sensitivity as compared to LC-MS/MS method using the same column and mass spectrometer, along with significant correlation and low mean difference bias on measurements. For analysis of trace 1,25-(OH)₂ VD₂ and 1,25-(OH)₂ VD₃ in normal human serum or plasma, further improvement of LOQ (like derivatization) should be considered. In conclusion, the use of supercritical fluid not only enhanced safety with reduced solvent cost, but also improved retention and sensitivity as compared to LC-MS/MS method. The developed SFC-MS/MS method is appropriate for high throughput analysis of multiple VD metabolites in human serum with reduced solvent and economic cost.

Association between Vitamin D Levels and Nonalcoholic Fatty Liver Disease: Potential Confounding Variables

Nonalcoholic fatty liver disease (NAFLD), historically considered to be the hepatic component of the metabolic syndrome, is a spectrum of fat-associated liver conditions, in the absence of secondary causes, that may progress to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Disease progression is closely associated with body weight or fatness, dyslipidemia, insulin resistance, oxidative stress, and inflammation. Recently, vitamin D deficiency has been linked to the pathogenesis and severity of NAFLD because of vitamin D "pleiotropic" functions, with roles in immune modulation, cell differentiation and proliferation, and regulation of inflammation. Indeed, several studies have reported an association between vitamin D and NAFLD/NASH. However, other studies have failed to find an association. Therefore, we sought to critically review the current evidence on the association between vitamin D deficiency and NAFLD/NASH, and to analyze and discuss some key variables that may interfere with this evaluation, such as host-, environment-, and heritability-related factors regulating vitamin D synthesis and metabolism; definitions of deficient or optimal vitamin D status with respect to skeletal and nonskeletal outcomes including NAFLD/NASH; methods of measuring 25(OH)D; and methods of diagnosing NAFLD as well as quantifying adiposity, the cardinal link between vitamin D deficiency and NAFLD.

Shedding Light on Vitamin D Status and Its Complexities during Pregnancy, Infancy and Childhood: An Australian Perspective

Ensuring that the entire Australian population is Vitamin D sufficient is challenging, given the wide range of latitudes spanned by the country, its multicultural population and highly urbanised lifestyle of the majority of its population. Specific issues related to the unique aspects of vitamin D metabolism during pregnancy and infancy further complicate how best to develop a universally safe and effective public health policy to ensure vitamin D adequacy for all. Furthermore, as Australia is considered a “sunny country”, it does not yet have a national vitamin D food supplementation policy. Rickets remains very uncommon in Australian infants and children, however it has been recognised for decades that infants of newly arrived immigrants remain particularly at risk. Yet vitamin D deficiency rickets is entirely preventable, with the caveat that when rickets occurs in the absence of preexisting risk factors and/or is poorly responsive to adequate treatment, consideration needs to be given to genetic forms of rickets.

Vitamin D in the Prevention and Treatment of Osteoarthritis: From Clinical Interventions to Cellular Evidence

Older adults are recommended vitamin D to prevent fractures. Though this population is also at risk of osteoarthritis (OA), the effect of vitamin D on OA is unclear and may differ by disease state. The relationship between vitamin D and OA during OA initiation and progression were considered in this narrative review of in vivo and in vitro studies. Regarding OA initiation in humans, the small number of published observational studies suggest a lack of association between induction of OA and vitamin D status. Most randomized controlled trials were performed in White OA patients with relatively high vitamin D status (>50 nmol/L). These studies found no benefit of vitamin D supplementation on OA progression. However, subset analyses and one randomized controlled pilot trial indicated that vitamin D supplementation may alleviate joint pain in OA patients with low vitamin D status (<50 nmol/L). As the etiology of OA is recently being more fully uncovered, better animal and cell models are needed. According to currently available clinical results, evidence is lacking to set a vitamin D level to prevent OA, and increasing vitamin D status above 50 nmol/L does not seem to benefit OA patients.

Vitamin D Status and Seasonal Variation among Danish Children and Adults: A Descriptive Study

The aim of the present study was to describe vitamin D status and seasonal variation in the general Danish population. In this study, 3092 persons aged 2 to 69 years (2565 adults, 527 children) had blood drawn twice (spring and autumn) between 2012 and 2014. A sub-sample of participants had blood samples taken monthly over a year. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured by liquid chromatography mass spectrometry, and information on supplement use was assessed from questionnaires. Seasonal variations in 25(OH)D concentrations were evaluated graphically and descriptively, and status according to age, sex, and supplement use was described. It was found that 86% of both adults and children were vitamin D-sufficient in either spring and or/autumn; however, many had a spring concentration below 50 nmol/L. A wide range of 25(OH)D concentrations were found in spring and autumn, with very low and very high values in both seasons. Among adults, women in general had higher median 25(OH)D concentrations than men. Furthermore, vitamin D supplement use was substantial and affected the median concentrations markedly, more so during spring than autumn. Seasonal variation was thus found to be substantial, and bi-seasonal measurements are vital in order to capture the sizable fluctuations in vitamin D status in this Nordic population.

Vitamin D deficiency and supplementation in critical illness-the known knowns and known unknowns

The burgeoning literature on vitamin D deficiency and supplementation over the past decade or so has generated a greater understanding of some areas but also an appreciation of the many areas of equipoise. This is particularly relevant in the field of critical care with the heterogeneous patient populations, the severity and duration of illness and the frequency of comorbid conditions.

This review aims to summarise the current knowledge base of vitamin D deficiency within the context of critical illness—“the known knowns”—and also highlight the areas of recognised uncertainty—“the known unknowns”. It acknowledges the fact that there may well be other knowledge gaps of clinical relevance of which we are currently unaware—“the unknown unknowns”.

Association of preconception serum 25-hydroxyvitamin D concentrations with livebirth and pregnancy loss: a prospective cohort study

BACKGROUND

Vitamin D deficiency during pregnancy is associated with adverse pregnancy outcomes, although the association between preconception vitamin D concentrations and livebirth is unknown. We aimed to assess the association between preconception vitamin D and pregnancy outcomes among women with proven fecundity.

METHODS

We did a secondary analysis of a prospective cohort from the block-randomised, double-blind, placebo-controlled EAGeR trial. Women aged 18-40 years with one to two previous pregnancy losses were recruited from June 15, 2007, to July 15, 2011, at four clinical sites in the USA and followed up for up to six menstrual cycles while attempting pregnancy and throughout pregnancy if they conceived. Serum 25-hydroxyvitamin D was measured at baseline (preconception) and 8 weeks of gestation. Outcomes of interest included clinical pregnancy, time to pregnancy, pregnancy loss, and livebirths. Risk ratios (RRs) and 95% CIs for livebirths, pregnancy, and pregnancy loss were estimated with weighted log-binomial regression. To assess time to pregnancy, we used discrete time Cox proportional hazards models to calculate fecundability odds ratios (FORs) with 95% CIs. EAGeR is registered with ClinicalTrials.gov, number NCT00467363.

FINDINGS

1191 women had available data on preconception 25-hydroxyvitamin D concentrations. 555 (47%) women were classified as having sufficient concentrations (≥75 nmol/L) and 636 (53%) as having insufficient concentrations (<75 nmol/L). Women with sufficient preconception 25-hydroxyvitamin D were more likely to achieve clinical pregnancy (adjusted RR 1·10 [1·01-1·20]) and livebirth (1·15 [95% CI 1·02-1·29]) than were women with insufficient concentrations. Among women who achieved pregnancy, sufficient preconception 25-hydroxyvitamin D, but not that at 8 weeks of gestation, was associated with reduced risk of pregnancy loss (preconception RR per 25 nmol/L 0·88 [95% CI 0·77-0·99]; 8 weeks of gestation 0·98 [0·95-1·01]). No association was observed with fecundability in women with sufficient versus those with insufficient preconception 25-hydroxyvitamin D concentrations (adjusted FOR 1·13 [95% CI 0·95-1·34]).

INTERPRETATION

Sufficient preconception 25-hydroxyvitamin D (≥75 nmol/L) was associated with increased likelihood of pregnancy and livebirth. Increased vitamin D concentrations before conception, but not in early pregnancy, were associated with reduced pregnancy loss.

FUNDING

National Institutes of Health and Doris Duke Charitable Foundation.

The association between 25(OH)D levels, frailty status and obesity indices in older adults

BACKGROUND

Vitamin D deficiency is common in older adults and has been linked with frailty and obesity, but it remains to be studied whether frail obese older adults are at higher risk of vitamin D deficiency. Therefore, the aim of this study is to explore the association between frailty, obesity indices and serum 25(OH)D concentrations.

METHODS

1447 individuals with 65 years or older, participating in a cross-sectional study (Nutrition UP 65) were included. Frailty, according to Fried et al., body mass index (BMI), waist circumference (WC), body roundness index (BRI) and body shape index (ABSI) were evaluated. A stepwise multinomial logistic regression was carried out to quantify the association between 25(OH)D quartiles and independent variables.

RESULTS

Median 25(OH)D levels were lower in individuals presenting both frailty and obesity (p<0.001). In the multivariate analysis, pre-frailty (OR: 2.65; 95% CI: 1.63-4.33) and frailty (OR: 3.77; 95% CI: 2.08-6.83) were associated with increased odds of lower 25(OH)D serum levels (first quartile). Regarding obesity indices, the highest categories of BMI (OR: 1.74; 95% CI: 1.06-2.86), WC (OR: 3.46; 95% CI: 1.95-6.15), BRI (OR: 4.35; 95% CI: 2.60-7.29) and ABSI (OR: 3.17 95% CI: 1.86-5.38) were directly associated with lower 25(OH)D serum levels (first quartile).

CONCLUSIONS

A positive association between frailty or obesity and lower vitamin D levels was found. Moreover, besides BMI and WC, other indicators of body adiposity, such as BRI and ABSI, were associated with lower 25(OH)D serum concentrations.

Vitamin D status and functional parameters: A cross-sectional study in an older population

The present study aims to clarify the association of vitamin D status with functionality, measured through gait speed and hand grip strength, in a sample of older adults, considering sex-specific characteristics and the potential confounding effect of lifestyle factors, disease, skin phenotype, season of blood collection and vitamin D supplementation. The Nutrition UP 65 cross-sectional study was conducted in a population-based sample of 1,425 older adults ≥ 65 years old. Serum levels of 25-hydroxyvitamin D were quantified through electrochemiluminescence immunoassay. Multinomial logistic regressions were carried out using quartiles of gait speed and of hand grip strength as dependent variables. Participants at risk of vitamin D inadequacy (30.0-49.9 nmol/L) and deficiency (< 30.0 nmol/L) presented higher adjusted odds ratio of the lowest values of gait speed and hand grip strength than those with adequate vitamin D levels (≥ 50.0 nmol/L). These associations were strongest among men at risk of vitamin D deficiency [adjusted odds ratio for the lowest quartile of gait speed = 3.24; 95% CI: 1.56–6.73 and for the lowest quartile of hand grip strength = 3.28; 95% CI: 1.47-7.31] than in women at risk of vitamin D deficiency [adjusted odds ratio for the lowest quartile of gait speed = 2.72; 95% CI: 1.37-5.41 and for the lowest quartile of hand grip strength = 1.56; 95% CI: 0.81–3.00]. In conclusion, in older adults, particularly in men, the risk of vitamin D deficiency was directly associated with the lowest values of gait speed and of hand grip strength. However, randomized controlled trials are needed to overcome the possibility of reverse causation and residual confounding. Present results emphasise the need for strategies to promote the reduction of the high prevalence of low vitamin D status among the Portuguese older adult population.

Can adverse effects of excessive vitamin D supplementation occur without developing hypervitaminosis D?

Vitamin D is a fat-soluble hormone that has endocrine, paracrine and autocrine functions. Consumption of vitamin D-supplemented food & drugs have increased significantly in the last couple of decades due to campaign and awareness programs. Despite such wide use of artificial vitamin D supplements, serum level of 25 hydroxyvitamin D does not always reflect the amount of uptake. In contrast to the safe sunlight exposure, prolonged and disproportionate consumption of vitamin D supplements may lead to vitamin D intoxication, even without developing hypervitaminosis D. One of the reasons why vitamin D supplementation is believed to be safe is, it rarely raises serum vitamin D levels to the toxic range even after repeated intravenous ingestion of extremely high doses of synthetic vitamin D analogs. However, prolonged consumption of vitamin D supplementation may induce hypercalcemia, hypercalciuria and hyperphosphatemia, which are considered to be the initial signs of vitamin D intoxication. It is likely that calcium and phosphorus dysregulation, induced by exogenous vitamin D supplementation, may lead to tissue and organ damages, even without developing hypervitaminosis D. It is needed to be emphasized that, because of tight homeostatic control of calcium and phosphorus, when hypercalcemia and/or hyperphosphatemia is apparent following vitamin D supplementation, the process of tissue and/or organ damage might already have been started.

Associations between serum vitamin D and the risk of female reproductive tumors: A meta-analysis with trial sequential analysis

BACKGROUND

Female reproductive tumors are common with high morbidity and mortality worldwide; however, the association between gynecological tumors and serum vitamin D is controversial. The aim of this meta-analysis was to evaluate the relationship between insufficiency of serum vitamin D and the occurrence of benign and malignant gynecological tumors.

METHODS

Studies from inception to June 2017 were searched in the electronic databases: National Library of Medicine (PubMed), Web of Science (Clerivate), and Cochrane Database of Systematic Reviews (Cochrane Library, CDSR) by 2 investigators independently. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random-effects model. STATA 12.0 Software and Trial Sequential Analysis (TSA) software were applied for data analyses.

RESULTS

Overall, 8 studies (including 2391 patients and 5798 patients with and without female reproductive tumors, respectively) were eligible for the present meta-analysis. In the subsequent meta-analysis, the occurrence of vitamin D deficiency in the case and control groups were 52.36% and 48.70%, respectively; women with female reproductive benign and malignant tumors were 55.57% and 50.59%, respectively. Although, no conclusive association was found between vitamin D deficiency and female reproductive tumors (OR, 1.05; 95% CI, 0.85-1.31); vitamin D deficiency may be a risk factor of malignant female reproductive neoplasm, as shown by the pooled OR (95% CI):1.17 (1.02-1.33). Furthermore, based on the OR values, association of vitamin D insufficiency with disease type, study location, number of patients, and methods for detecting CLA was observed. Similar results in the sensitivity analysis were observed. TSA showed that the cumulative Z-curve crossed the traditional boundary line, rather than crossing the trial sequential monitoring boundary. However, the cumulative information failed to reach the required information size.

CONCLUSIONS

Currently, vitamin D deficiency appears to be a common issue in females, and there may be an urgent need to improve the level of vitamin D. Furthermore, vitamin D deficiency may be a non-negligible risk factor of malignant female reproductive neoplasm. Undoubtedly, more trials are required in the future according to TSA.

Vitamin D and Cancer Risk and Mortality: State of the Science, Gaps, and Challenges

There has been substantial enthusiasm recently regarding the potential role of vitamin D in the primary and secondary prevention of cancer. Laboratory studies demonstrate a range of anticarcinogenic effects for vitamin D compounds, but human studies have yielded little consistent evidence supporting a protective association. Higher circulating levels of vitamin D (i.e., 25-hydroxyvitamin D or 25(OH)D) appear to be associated with reduced risk of colorectal and bladder malignancies, but higher risk of prostate and possibly pancreatic cancers, with no clear association for most other organ sites examined. Despite there being no official institutional recommendations regarding the use of vitamin D supplements for cancer prevention, screenings for vitamin D deficiency and vitamin D supplement use have increased substantially over the past decade. These widespread practices demonstrate that population sociobehavioral changes are often adopted before scientifically well-informed policies and recommendations are available. This review critically examines the currently available epidemiologic literature regarding the associations between circulating 25(OH)D, vitamin D supplementation, and vitamin D-related genetic variation and cancer risk and mortality, with a particular emphasis on prospective studies. We identify several important gaps in our scientific knowledge that should be addressed in order to provide sufficient reproducible data to inform evidence-based recommendations related to optimal 25(OH)D concentrations (and any role for vitamin D supplementation) for the primary and secondary prevention of cancer. With few exceptions, such recommendations cannot be made at this time.

Prevalence and Predictors of Low Serum 25-Hydroxyvitamin D among Female African-American Breast Cancer Survivors

BACKGROUND

African-American breast cancer survivors commonly demonstrate low serum 25-hydroxyvitamin D (25(OH)D). Decreased cutaneous conversion, high levels of adiposity, and even breast cancer treatment may influence vitamin D status. Previous investigations have analyzed African-American women in aggregate with other breast cancer survivors and have not comprehensively addressed these influential factors.

OBJECTIVES

To determine the prevalence of low serum 25(OH)D in an exclusively African-American cohort of female breast cancer survivors with overweight/obesity and to evaluate the role of ultraviolet (UV) light exposure, body composition, and dietary sources of vitamin D on serum 25(OH)D levels.

DESIGN

Cross-sectional.

PARTICIPANTS

Pre- and postmenopausal African-American breast cancer survivors (n=244) were recruited from various neighborhoods in the city of Chicago, IL, between September 2011 and September 2014 for a larger weight loss trial.

MAIN OUTCOME MEASURES

Demographic, clinical, anthropometric (body mass index [calculated as kg/m²], waist circumference, and hip circumference), blood specimen, dietary intake (food frequency questionnaire), and sun behavior data were collected by trained study personnel before trial participation. Dual-energy x-ray absorptiometry was used to quantify adiposity (total, percentage, regional, visceral) and lean mass. Serum 25(OH)D was used as the biomarker reflective of vitamin D status.

STATISTICAL ANALYSES

Mean (±standard deviation), frequencies, and multivariate linear regression modeling.

RESULTS

The average participant was 57.4 years old (±10.0), 6.9 years (±5.2) from initial breast cancer diagnosis with a body mass index of 36.2 (±6.2). The majority of participants (60%) reported habitual oral vitamin D supplementation with mean intake of 327 IU (±169). Vitamin D deficiency was prevalent in 81% and 43%, when the cut points of the Endocrine Society (<30 ng/mL or <75 nmol/L) and the Institute of Medicine (<20 ng/mL or <50 nmol/L) were applied, respectively. A multivariate model adjusting for age, seasonality of blood draw, total energy intake, use of supplemental vitamin D, darker skin pigmentation, breast cancer stage, and waist-to-hip ratio was able to explain 28.8% of the observed variance in serum 25(OH)D concentrations. No significant associations were detected for body mass index or any dual-energy x-ray absorptiometry measures of body composition.

CONCLUSIONS

Considering the number of women who endorsed use of vitamin D supplementation, the prevalence of vitamin D deficiency among these African-American breast cancer survivors was high. Vitamin D supplementation, sun behavior, and waist-to-hip ratio may serve as future points of intervention to improve the vitamin D status of this minority survivor population.

The Convergence of Two Epidemics: Vitamin D Deficiency in Obese School-aged Children

PROBLEM

Vitamin D deficiency (VDD) and obesity are two interrelated global epidemics that affect school-aged children. This article will review the relationship between VDD and obesity in school-aged children and implications it has for the pediatric nurse (PN).

ELIGIBILITY CRITERIA

Original articles of studies, review articles and meta-analyses were selected from the past 5years and pooled for review. These included obese school-aged children who had vitamin D insufficiency. The latest guidelines concerning the issue were also included.

SAMPLE

Children 6-12years of age with obesity and vitamin D insufficiency.

RESULTS

This review strongly implies obesity in children being a strong risk factor for VDD. Prevention of VDD starts with lifestyle changes and adequate dietary intake of fortified foods and current screening recommendations for VDD are inconsistent. Vitamin D supplementation is recommended with inadequate intake or deficient serum 25-hydroxyvitamin D levels or signs of hypocalcemia. Supplementation doses differ based on whether VDD is being prevented or being treated and in obese children, the Endocrine Society recommends a dose that is two to three times higher than for normal weight children. Subclinical signs and symptoms of VDD include musculoskeletal pain, fractures, reduced bone density and reduced immunity.

CONCLUSIONS

Whereas obesity is a strong risk factor for VDD, more research is needed to clarify the role of VDD as a risk factor for obesity.

IMPLICATIONS

The PN plays an essential role in preventing, screening for, assessing for, treating and counseling on VDD in obese school-aged children.

Vitamin D and cardiovascular diseases: Causality

Vitamin D regulates blood pressure, cardiac functions, and endothelial and smooth muscle cell functions, thus, playing an important role in cardiovascular health. Observational studies report associations between vitamin D deficiency with hypertension and cardiovascular-related deaths. Peer-reviewed papers were examined in several research databases as per the guidelines of the Preferred Reporting Items for Systematic Reviews, using key words that address the relationship between vitamin D and cardiovascular disease. Correlations and interpretations were made considering the risks-benefits, broader evidence, and implications. This review analyzed current knowledge regarding the effects of vitamin D on the cardiovascular system. 1,25(OH)₂D and related epigenetic modifications subdue cellular inflammation, improve overall endothelial functions, reduce age-related systolic hypertension and vascular rigidity, and attenuate the actions of the renin-angiotensin-aldosterone system. Most observational and ecological studies support 25(OH)vitamin D having protective effects on the cardiovascular system. However, the association of vitamin D deficiency with cardiovascular diseases is based primarily on observational and ecological studies and thus, is a matter of controversy. Adequately powered, randomized controlled clinical trial data are not available to confirm these associations. Thus, to test the hypothesis that correction of vitamin D deficiency protects the cardiovascular system, well-designed, statistically powered, longer-term clinical trials are needed in persons with vitamin D deficiency. Nevertheless, the available data support that adequate vitamin D supplementation and/or sensible sunlight exposure to achieve optimal vitamin D status are important in the prevention of cardiovascular disease and other chronic diseases.

Vitamin D in adolescence: evidence-based dietary requirements and implications for public health policy

Vitamin D is a unique nutrient. First, it acts as a pro-hormone and secondly, the requirement for vitamin D can be met by both endogenous synthesis from sunlight and by dietary sources. This complicates the determination of dietary requirements for vitamin D, which along with the definition of optimal vitamin D status, have been highly controversial and much debated over recent years. Adolescents are a population group at high risk of low vitamin D status, which is concerning given the important role of vitamin D, and calcium, in promoting normal bone mineralisation and attainment of peak bone mass during this rapid growth phase. Dietary vitamin D recommendations are important from a public health perspective in helping to avoid deficiency and optimise vitamin D status for health. However limited experimental data from winter-based dose-response randomised trials in adolescents has hindered the development of evidence-based dietary requirements for vitamin D in this population group. This review will highlight how specifically designed randomised trials and the approach adopted for estimating such requirements can lead to improved recommendations. Such data indicate that vitamin D intakes of between 10 and about 30 µg/d may be required to avoid deficiency and ensure adequacy in adolescents, considerably greater than the current recommendations of 10-15 µg/d. Finally this review will consider the implications of this on public health policy, in terms of future refinements of vitamin D requirement recommendations and prioritisation of public health strategies to help prevent vitamin D deficiency.