Search

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 value0.05 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 r

We investigated the effect of daily intake of yogurt drink fortified with either vitamin D alone or with added calcium on resting metabolic rate (RMR), thyroid hormones and homeostatic model assessment for insulin resistance in subjects with type 2 diabetes (T2D). A total of 75 adult subjects with T2D were randomly assigned to 1 of the 3 groups to receive either D-fortified yogurt drink (DY; 1000 IU vitamin D/day), Ca-D-fortified yogurt drink (CDY; 1000 IU vitamin D plus 500 mg calcium), or plain yogurt drink for 12 weeks. All assessments were done at the baseline and after the intervention. The concentrations of anti-thyroid peroxidase antibody (anti-TPO-Ab), intact parathyroid hormone (iPTH) and thyroid stimulating hormone (TSH) had declined significantly compared with baseline values only in the CDY group. The mean RMR increased in both DY and CDY groups (p < 0.001 for both). Also, changes of serum concentrations of 25-hydroxycalciferol (B = 2.96, 95% confidence interval (CI) = 1.3 to 4.6, p = 0.001) and iPTH (B = –2.41, 95% CI = –4.5 to –0.31, p = 0.025) remained significant predictors of RMR changes even after adjustment for changes of serum concentrations of TSH (B = –18.2, 95% CI = –61.7 to 25.2, p = 0.406). Daily intake of vitamin D together with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Also, vitamin D with or without added calcium causes a significant thyroid-independent increase in RMR in euthyroid subjects with T2D. Registered at clinicaltrials.gov as NCT01229891. Novelty: Daily intake of vitamin D with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Vitamin D with or without added calcium causes a thyroid-independent increase in RMR in euthyroid subjects with T2D.

Serum 25-hydroxyvitamin D [25(OH)D] concentration represents the body's reserves of vitamin D, which is mostly used by clinicians to evaluate the storage status of vitamin D in the body. The present study aimed to investigate the serum vitamin D components in different health status of minors to correctly evaluate the vitamin D storage in vivo. A total of 2,270 minors were included in the study, which was divided into healthy group (1,204 cases) and disease group (1,066 cases, including 270 short stature, 433 respiratory infections, 175 malnutrition and 188 tic disorder subjects). The levels of 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] were measured by UHPLC-MS/MS in all subjects, and the 25(OH)D3 activity equivalents [25(OH)D3-AE] and 25(OH)D were calculated. In addition, the 3-epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3] concentrations of 278 subjects (including 147 healthy and 131 disease subjects) were measured by random sampling. 25(OH)D2, 25(OH)D3, 25(OH)D and 25(OH)D3-AE levels in disease group were significantly lower than those in healthy group (p

The aim of the current study was to establish a reliable candidate reference method for serum 25-hydroxyvitamin D [25(OH)D] measurement and to assess the commutability of multiple control materials among liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods.Serum 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] together with spiked internal standards were extracted with a one-step approach and then analyzed by LC-MS/MS. The commutability assessment for 25(OH)D was conducted according to the Clinical and Laboratory Standards Institute (CLSI) EP14-A3 protocol. 25(OH)D concentrations in 5 levels of unprocessed serum pools, 7 levels of serum pools spiked with 25(OH)D3 or 25(OH)D2, 3 levels of commercial control materials, 2 levels of spiked bovine serum, and 4 levels of external quality assessment (EQA) materials were measured along with 30 single-donor samples using the candidate reference method and two routine LC-MS/MS methods.The candidate reference method could separate 25(OH)D2 and 25(OH)D3 from 14 potential interfering compounds completely within a 9-min analysis time. Good method precision was obtained, and measurement results on certified reference material NIST SRM 972a were within the uncertainty of the certified values. All candidate materials were assessed commutable for LC-MS/MS methods.The candidate reference method for serum 25(OH)D measurement is precise, accurate, and robust against interferences and can provide an accuracy base for routine methods. The multiple alternative control materials with commutability among LC-MS/MS methods will facilitate the further standardization for serum 25(OH)D measurement.

Vitamin D plays an important role not only in bone health but also in many other body functions. Vitamin D deficiency is very common in the general population. Measurement of blood 25-hydroxyvitamin D is a common practice to evaluate vitamin D deficiency. Immunoassays and liquid chromatography tandem mass spectrometry (LC-MS/MS) are the most commonly used methods for the measurement of 25-hydroxyvitamin D. Immunoassays suffer from specificity issues and do not distinguish between 25-hydroxyvitamin D2 and D3. Therefore, LC-MS/MS is a preferred method for quantification of 25-hydroxyvitamin. We describe an LC-MS/MS method, which involves protein precipitation and analysis of the extract using atmospheric pressure chemical ionization and multiple reaction monitoring. 25-hydroxyvitamin D3-d6 is used as an internal standard. The method is linear from 1-100 ng/mL for both 25-hydroxyvitamin D2 and D3 and has imprecision of10%.

The majority of circulating 25-hydroxyvitamin D (25(OH)D) is protein bound and perhaps less available than the free fraction of 25(OH)D; therefore, researchers have proposed that the measurement of free 25(OH)D in human serum may be a better indicator of vitamin D health status than total 25(OH)D. The availability of a new enzyme-linked immunosorbent assay (ELISA) for the determination of free 25(OH)D provides a method for direct measurement of the low levels of non-protein bound 25(OH)D. As an initial step towards harmonization of measurements of free 25(OH)D, the ELISA was used to measure free 25(OH)D in three existing Standard Reference Materials (SRMs): SRM 972a Vitamin D Metabolites in Frozen Human Serum, SRM 2973 Vitamin D Metabolites in Frozen Human Serum (High Level), and SRM 1949 Frozen Prenatal Human Serum. Target values for free 25(OH)D in the nine SRM serum pools, obtained by combining the results from two laboratories, ranged from 3.76 ± 0.36 to 10.0 ± 0.58 pg/mL. Of particular significance is the assignment of free 25(OH)D target values to SRM 1949, which consists of four serum pools from non-pregnant female donors of reproductive age and pregnant women in each of the three trimesters and which also has values assigned for vitamin D binding protein, which increases during pregnancy. The availability of target values for free 25(OH)D in these SRMs will allow researchers to validate new analytical methods and to compare their results with other researchers as an initial step towards harmonization of measurements among different studies and laboratories.

An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of ligand binding assays (Part 2) for the determination of serum total 25-hydroxyvitamin D [25(OH)D]. Fifty single-donor samples were assigned target values for concentrations of 25-hydroxyvitamin D(2) [25(OH)D(2)], 25-hydroxyvitamin D(3) [25(OH)D(3)], 3-epi-25-hydroxyvitamin D(3) [3-epi-25(OH)D(3)], and 24R,25-dihydroxyvitamin D(3) [24R,25(OH)(2)D(3)] using isotope dilution liquid chromatography – tandem mass spectrometry (ID LC-MS/MS). VDSP Intercomparison Study 2 Part 2 includes results from 17 laboratories using 32 ligand binding assays. Assay performance was evaluated using mean % bias compared to the assigned target values and using linear regression analysis of the test assay mean results and the target values. Only 50% of the ligand binding assays achieved the VDSP criterion of mean % bias ≤ |±5%|. For the 13 unique ligand binding assays evaluated in this study, only 4 assays were consistently within ±5% mean bias and 4 assays were consistently outside ±5% mean bias regardless of the laboratory performing the assay. Based on multivariable regression analysis using the concentrations of individual vitamin D metabolites in the 50 single-donor samples, most assays underestimate 25(OH)D(2) and several assays (Abbott, bioMérieux, DiaSorin, IDS-EIA, and IDS-iSYS) may have cross-reactivity from 24R,25(OH)(2)D(3). The results of this interlaboratory study represent the most comprehensive comparison of 25(OH)D ligand binding assays published to date and is the only study to assess the impact of 24R,25(OH)(2)D(3) content using results from a reference measurement procedure.

Objective We developed an assay to measure the concentration of 25 hydroxyvitamin D2 and D3 in protein extracts derived from stored neonatal dried blood spots. During this study, we postulated that these samples had been contaminated with exogenous vitamin D metabolites because of the addition of bovine serum albumin (BSA) as part of an extraction step undertaken 7 years earlier. The aim of the current study was to develop methods in order to adjust for this contamination. Results We identified between-plate variations in 25 hydroxyvitamin D2 and D3 concentrations which suggested the presence of three different BSA batches. Based on repeat extraction (without the addition of BSA) and testing of 395 samples, we developed models to correct for the exogenous 25 hydroxyvitamin D2 and D3. The regression models were Diff25OHD3 = − 8.2 + 1.8* Diff25OHD2 for low contamination, Diff25OHD3 = 23.8 + 1.7* Diff25OHD2 for middle contamination, and Diff25OHD3 = 14.3 + 3.0* Diff25OHD2 for high contamination. After these corrections, the three subsamples had comparable distributions within the expected range for both 25 hydroxyvitamin D2 and D3.

BackgroundNumerous studies in veterinary species have recently linked vitamin D status with non-skeletal health disorders. Previous studies have indicated that dogs cannot produce endogenous vitamin D via cutaneous production and rely solely on dietary intake of vitamin D. The seasonal variation of vitamin D seen in humans due to changes in UV exposure therefore is unlikely to be replicated in these animals.ObjectivesThe objective of this study was to investigate the natural variation in 25-hydroxyvitamin-D concentration in dogs subject to seasonal UV exposure.MethodsThis longitudinal study followed 18 healthy dogs fed a standardized diet over one year, with blood samples obtained monthly. Two key vitamin D metabolites, 25-hydroxyvitamin-D2 and 25-hydroxyvitamin-D3, were assessed by liquid chromatography tandem mass spectrometry in serum samples. Various other biochemical parameters were also measured. Seasonality was assessed using Cosinor statistical analysis.ResultsAlthough the dogs were subject to seasonally varying UV radiation, 25-hydroxyvitamin-D and related biomarkers (including calcium and parathyroid hormone) remained stable over time and did not follow a seasonal pattern. 25-hydroxyvitamin-D was not positively correlated to exposure to UV radiation. Nonetheless, variation in 25-hydroxyvitamin-D concentration between individual dogs was detected.ConclusionsGiven the standardization of diet, we concluded that the seasonal stability of 25-hydroxyvitamin-D concentration (vitamin D status) was likely a direct result of lack of cutaneous vitamin D production in this species and highlights the importance of dietary intake. The variation in 25-hydroxyvitamin-D concentration between animals warrants further investigatio

Background: Vitamin D deficiency is prevalent globally and there is lack of evidence as to how 25(OH)D2 contributes to vitamin D status. The aim of this study was to describe vitamin D status and to assess the role of vitamin D2, a dietary vitamin D source, against the vitamin D status of children aged 3–5 years in China. Methods: Data were extracted from the Chinese National Nutrition and Health Surveillance (CNNHS) in 2013. The concentration of serum 25(OH)D2 and 25(OH)D3 was measured by using LC-MS/MS. Results: A total of 1435 subjects were enrolled and serum 25(OH)D were analyzed. The prevalence of total serum 25(OH)D &lt, 30 nmol/L was 8.9%. Serum 25(OH)D2 was detected in 10.9% of the studied children. After adjusting for confounding factors, total 25(OH)D concentration was 8.48 nmol/L lower and odds ratio of vitamin D deficiency was 4.20 times (OR (95%CI): 4.20 (1.64, 10.77)) in children without 25(OH)D2 than those with 25(OH)D2 detected. Conclusions: Vitamin D deficiency was common among children aged 3–5 years in China. Vitamin D2 may play a role in preventing vitamin D deficiency in Chinese children aged 3–5 years.

To determine predictors of 25-hydroxyvitamin DData on sociodemographic, obstetric, lifestyle and pregnancy characteristics, including serum 25(OH)DIn the third trimester, 25(OH)DSeasonality and vitamin A status were important predictors of 25(OH)D

Vitamin D plays an important role in the absorption of calcium and phosphorus, bone metabolism. Various analytical methods are being used to measure the circulating vitamin D levels in the blood. Among all vitamin D metabolites, 25 hydroxyvitamin (25(OH) D) is the most well-known member of the vitamin D family. It is available in two forms, viz. 25 hydroxyvitamin D

This study investigated whether UVB-exposed wheat germ oil (WGO) is capable to improving the vitamin D status in healthy volunteers.A randomized controlled human-intervention trial in parallel design was conducted in Jena (Germany) between February and April. Ultimately, 46 healthy males and females with low mean 25-hydroxyvitamin D (25(OH)D) levels (34.9 ± 10.6 nmol/L) were randomized into three groups receiving either no WGO oil (control, n = 14), 10 g non-exposed WGO per day (- UVB WGO, n = 16) or 10 g WGO, which was exposed for 10 min to ultraviolet B-light (UVB, intensity 500-630 µW/cmParticipants who received the UVB-exposed WGO were characterized by an increase of circulating 25(OH)DUVB-exposed WGO containing 23.7 µg vitamin D can increase 25(OH)DClinicalTrials.gov: NCT03499327 (registered, April 13, 2018).

The aim of this study was to investigate the relationship between 25-hydroxyvitamin DThis nested case-control study was drawn from the H-type Hypertension and Stroke Prevention and Control Project, a community-based, prospective, observational study. Plasma 25(OH)DWe included 1079 participants with ischemic stroke and 1079 matched controls. Due to a non-linear relationship, the analyses were stratified by 25(OH)DAn inverse dose-response association between 25(OH)D

Background: As life expectancy increases, cognitive performance decline in the elderly has become one of the major global challenges. We aimed to evaluate the association of dietary vitamin D (VD), serum 25-hydroxyvitamin D3 (25(OH)D3), 25-hydroxyvitamin D2 (25(OH)D2), and total 25-hydroxyvitamin (25(OH)D) concentration with cognitive performance in older Americans. Methods: The data from the National Health and Nutrition Examination Survey (NHANES), 2011–2014 was used. The cognitive performance was assessed by the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) Word Learning sub-test, Animal Fluency test, and Digit Symbol Substitution Test (DSST). A binary logistic regression model was applied to evaluate the association between VD and cognitive performance, and restricted cubic spline model was adopted to evaluate the dose–response relationship. Results: While comparing to the lowest dietary VD intake group, the multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of the highest dietary VD intake group were 0.51 (0.36–0.72) for the Animal Fluency test score and 0.45 (0.31–0.66) for DSST score, respectively; and those of serum total 25(OH)D and 25(OH)D3 concentration were 0.68 (0.47–0.97) and 0.62 (0.44–0.86) for DSST score. L-shaped relationships were identified for dietary VD intake, serum total 25(OH)D and 25(OH)D3 concentration with cognition performance. The associations between dietary VD intake, serum total 25(OH)D and cognitive performance were non-significant when stratified by gender. Conclusions: The study indicates that dietary VD intake, serum total 25(OH)D and 25(OH)D3 concentration were positively associated with cognitive performance. Further studies are needed to clarify the possible effects of dietary VD intake and serum 25(OH)D2, 25(OH)D3 on cognitive performance.

Objectives Studies investigating the association between vitamin D and severity of COVID-19 have mixed results perhaps due to immunoassay assessment of total 25-hydroxyvitamin D (tD) (the sum of 25-hydroxyvitamin-D2 [25-OH-D2] and 25-hydroxyvitamin-D3 [25-OH-D3]). Liquid chromatography tandem mass spectrometry (LC-MS/MS) has high analytical specificity and sensitivity for 25-OH-D2 and 25-OH-D3, and thus enables a more accurate assessment of impact on COVID-19 outcomes. Methods We established reference intervals for 25-OH-D3 and tD using LC-MS/MS. 25-OH-D2, 25-OH-D3 and tD were quantitated for 88 COVID-19 positive and 122 COVID-19 negative specimens. Chi-square or Fisher’s exact tests were used to test associations in binary variables. T-Tests or Wilcoxon rank sum tests were used for continuous variables. Cox proportional hazards were used to test associations between 25-OH-D3 or tD levels and length of stay (LOS). For mortality and ventilation, logistic regression models were used. Results COVID-19 patients with deficient ( Conclusions There is an inverse relationship of 25-hydroxyvitamin D levels and hospital LOS for COVID-19 patients. Vitamin D status is a predictor for severity of outcomes. LCMS results are useful for assessing the odds of mortality and the need for ventilation during hospitalization.

Background Vitamin A and E are routinely monitored to assess nutritional status. The most commonly used approach for their measurement involves laborious liquid-liquid extraction followed by high-performance liquid chromatography (HPLC) analysis on dedicated instrumentation. We describe a simple, rapid protocol for measurement of vitamin A and E and their integration into an existing online sample preparation liquid chromatography tandem mass spectrometry (SPLC-MS/MS) workflow. Methods We performed a method comparison between the SPLC-MS/MS and HPLC methods for vitamin A and E by measuring patient specimens across the concentration range 11–81 µg/dL for vitamin A and 1–18 mg/L for vitamin E. The analysis times on each platform were also compared. Results SPLC-MS/MS and HPLC methods were comparable with regards to analytical performance; mean bias across the measured range was 2.54% (95% CL: −11.56–16.64%) for vitamin A and −2.04% (95% CL: −18.20–14.12%) for vitamin E. Total analysis times were 7 min and 15 min for SPLC-MS/MS and HPLC respectively. Conclusions The development of a simplified sample preparation protocol and the use of multiplexing SPLC-MS/MS have reduced sample analysis times for vitamin A and E. This method has also optimized clinical workflow through consolidation of previously independent benches.

Ion mobility was integrated with liquid chromatography/high resolution mass spectrometry (LC/IM-HRMS) to quantify 25-hydroxyvitamin D (25OHD) in human serum. It has previously been shown that 25OHD adopts two gas-phase conformations which are resolved using ion mobility; in contrast, the inactive epimer, 3-epi-25-hydroxyvitamin D (epi25OHD) only adopts one. Interference from epi25OHD was eliminated by filtering the chromatogram to retain the drift time that corresponds to the unique gas-phase conformation of 25OHD. Although ion mobility separates the epimers, some chromatography is required to separate compounds which interfere with ionization or fall at the same nominal m/z. Standards were prepared in 4% albumin solutions and compared against commercial serum quality controls. Standards and quality controls were analyzed and validated using a two-minute LC/IM-MS method. 25-hydroxyvitamin D3 and D2 were quantified over the range between 2 and 500 ng/mL with bias and precision within 15%. When epi25OHD was spiked into quality control samples, no significant bias was introduced, and analysis of 30 patient samples shows good agreement between this LC/IM-MS and traditional LC/MS/MS methods. This work shows that ion mobility can be incorporated with liquid chromatography and mass spectrometry for rapid quantitation of 25OHD in human serum.

Background. Placental soluble fms-like tyrosine kinase-1 (sFlt-1), an antagonist of vascular endothelial growth factor, is considered an etiological factor of endothelial damage in pregnancy pathologies. An increase in the sFlt-1 level is associated with alterations of endothelial integrity. In contrast, vitamin D exerts a protective effect and low concentrations of 25(OH)D may have an adverse effect on common complications of pregnancy, such as gestational hypertension (GH), preeclampsia (PE), and gestational diabetes mellitus (GDM). The aim of this study was to analyze the levels of sFlt-1 in Polish women with physiological pregnancies and pregnancies complicated by GH, PE, and GDM. Moreover, we analyzed relationships between the maternal serum sFlt-1 level and the sFlt-1 to 25(OH)D ratio and the risk of GH and PE. Material and Methods. The study included 171 women with complicated pregnancies; among them are 45 with GH, 23 with PE, and 103 with GDM. The control group was comprised of 36 women with physiological pregnancies. Concentrations of sFl-1 and 25(OH)D were measured before delivery, with commercially available immunoassays. Results. Women with GH differed significantly from the controls in terms of their serum sFlt-1 levels (5797 pg/ml vs. 3531 pg/ml, p=0.0014). Moreover, a significant difference in sFlt-1 concentrations was found between women with PE and those with physiological pregnancies (6074 pg/ml vs. 3531 pg/ml, p<0.0001). GDM did not exert a statistically significant effect on serum sFlt-1 levels. Both logistic regression and ROC analysis demonstrated that elevated concentration of sFlt-1 was associated with greater risk of GH (AUC=0.70, p=0.0001) and PE (AUC=0.82, p<0.0001). Also, the sFlt-1 to 25(OH)D ratio, with the cutoff values of 652 (AUC=0.74, p<0.0001) and 653 (AUC=0.88, p<0.0001), respectively, was identified as a significant predictor of GH and PE. Conclusions. Determination of the sFlt-1/25(OH)D ratio might provide additional important information and, thus, be helpful in the identification of patients with PE and GH, facilitating their qualification for intensive treatment and improving the neonatal outcomes.

The human body's vitamin D levels are determined by measuring the level of 25-hydroxy-vitamin D3 (25-OH-vitamin D3) in human serum. In this research, a fast, simple, efficient and highly sensitive low-density solvent based on dispersive liquid-liquid microextraction (DLLME) was employed for the successful determination of 25-OH-vitamin D3 from complex human serum matrices. Reversed phase high-performance liquid chromatography was used as a powerful technique. The important parameters in the low-density solvent-DLLME method were optimized using response surface methodology based on central composite design. The calibration curves displayed a high level of linearity (R2 > 0.997) for 25-OH-vitamin D3 in the range of 2-500 ng mL-1. The limit of detection and limit of quantitation were 0.6 ng mL-1 and 1.9 ng mL-1, respectively. The relative standard deviation for the seven analyses was 7.1%. The relative recoveries of vitamin D3 in spiked human serum samples were between 85% and 97%. The amount of 25-OH-vitamin D3 in samples was determined using the proposed method and acceptable results were reported.

This study assessed the heritability of 25 hydroxyvitamin D3 (25(OH)D3) in a large twin cohort and the shared effect of sun exposure and skin colour on 25(OH)D3 variance. Study participants included 1604 twin pairs and their siblings (n = 4020). Twin correlations for 25(OH)D3 concentration were rMZ=0.79 (584 pairs) and rDZ = 0.52 (1020 pairs) consistent with an average h2 = 0.50 throughout the year. Significant phenotypic and genetic seasonal fluctuation was observed in 25(OH)D3 concentrations with heritability decreasing during the winter (h2 = 0.37) compared to summer (h2 = 0.62). Skin colour (measured both ordinally and quantitatively) and self-reported sun exposure were found to significantly affect 25(OH)D3 concentration. Twins with olive/dark skin had significantly lower 25(OH)D3 concentrations than those with fair/pale skin and multivariate genetic analysis showed that approximately half of the total additive genetic variation in 25(OH)D3 results from genes whose primary influence is on skin colour and sun exposure. Additionally, 37% of the total variance was attributed to shared environmental effects on vitamin D, skin colour and sun exposure measures. These results support a moderate estimate of vitamin D heritability and suggest significant influence of season, skin colour and sun exposure on the genetic variance.

Introduction. Current studies support the implication of metabolic changes associated with type 2 diabetes in altering bone metabolism, structure and resistance. Objective. We conducted a cross-sectional study on postmenopausal women aimed to analyze the differences in metabolic and bone profile in patients with and without type 2 diabetes Methods. We analyzed the metabolic and bone profile in postmenopausal women with and without type 2 diabetes (T2DM). Clinical, metabolic, hormonal parameters, along with lumbar, hip and femoral bone mineral density (BMD) and trabecular bone score (TBS) were evaluated. Results. 56 women with T2DM(63.57±8.97 years) and 83 non-T2DM (60.21±8.77 years) were included. T2DM patients presented a higher value of body mass index (BMI) and BMD vs. control group (p = 0.001; p = 0.03-lumbar level, p = 0.07-femoral neck and p = 0.001-total hip). Also, BMI correlated positively with lumbar-BMD and glycated hemoglobin (HbA1c) (r = 0.348, p = 0.01; r = 0.269, p = 0.04), correlation maintained even after age and estimated glomerular filtration rate (eGFR) adjustment (r = 0.383, p = 0.005; r = 0.237, p = 0.08). Diabetic patients recorded lower levels of 25(OH)D(p = 0.05), bone markers (p ≤ 0.05) and TBS(p = 0.07). For the entire patient group we found a negative correlation between HbA1c level and bone markers: r = -0.358, p = 0.0005-osteocalcin, r = -0.40, p = 0.0005-P1NP, r = -0.258, p = 0.005-crosslaps. Conclusions. Our results indicate the presence of altered bone microarchitecture in T2DZ patients according to the TBS score, combined with lower levels of bone markers, with a statistically significant negative correlation between HbA1c level and bone markers.

Background Reference measurement procedures (RMP) have rigorous accuracy specifications. For total 25-hydroxyvitamin D, 25(OH)D, bias ≤1.7% and CV ≤5% are recommended. These quality specifications are impractical for minor analytes, such as 25(OH)D2. Furthermore, documentation on RMP quality performance specifications for the individual 25(OH)D metabolites and their daily application are missing. Methods To assess accuracy, we used zeta-scores. Daily, 5–10 specimens (duplicate) and 3 reference materials (singleton or duplicate) were measured for 25(OH)D3 and 25(OH)D2 using JCTLM-accepted LC-MS/MS RMPs. Protocols were repeated on 3–4 occasions to generate campaign results. We used separate zeta-score acceptability criteria for daily (≤|2|) and campaign (≤|1|) evaluations. Allowable imprecision was determined experimentally. Results Across 7 campaigns, unacceptable daily zeta-scores required repeating 2 runs for 25(OH)D3 and 5 runs for 25(OH)D2. Hence, the zeta-scores of acceptable reference material results indicated high accuracy. The allowable imprecision for the RMPs was ≤5% (daily) and ≤ 3% (campaign) for 25(OH)D3 and ≤ 7% (daily) and ≤ 4% (campaign) for 25(OH)D2, respectively. Conclusions Using zeta-scores and experimentally derived imprecision, we developed a straightforward approach to assess the acceptability of individual 25(OH)D reference measurements, providing also much-needed practical accuracy specifications for 25(OH)D2.

An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of liquid chromatography - tandem mass spectrometry (LC-MS/MS) assays used for the determination of serum total 25-hydroxyvitamin D (25(OH)D), which is the sum of 25-hydroxyvitamin D

BACKGROUND: The role of vitamin D supplementation as a treatment for COVID-19 has been a subject of considerable discussion. A thorough understanding of the current evidence regarding the effectiveness and safety of vitamin D supplementation for COVID-19 based on randomised controlled trials is required. OBJECTIVES: To assess whether vitamin D supplementation is effective and safe for the treatment of COVID-19 in comparison to an active comparator, placebo, or standard of care alone, and to maintain the currency of the evidence, using a living systematic review approach. SEARCH METHODS: We searched the Cochrane COVID-19 Study Register, Web of Science and the WHO COVID-19 Global literature on coronavirus disease to identify completed and ongoing studies without language restrictions to 11 March 2021. SELECTION CRITERIA: We followed standard Cochrane methodology. We included randomised controlled trials (RCTs) evaluating vitamin D supplementation for people with COVID-19, irrespective of disease severity, age, gender or ethnicity. We excluded studies investigating preventive effects, or studies including populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)). DATA COLLECTION AND ANALYSIS: We followed standard Cochrane methodology. To assess bias in included studies, we used the Cochrane risk of bias tool (ROB 2) for RCTs. We rated the certainty of evidence using the GRADE approach for the following prioritised outcome categories: individuals with moderate or severe COVID-19: all-cause mortality, clinical status, quality of life, adverse events, serious adverse events, and for individuals with asymptomatic or mild disease: all-cause mortality, development of severe clinical COVID-19 symptoms, quality of life, adverse events, serious adverse events. MAIN RESULTS: We identified three RCTs with 356 participants, of whom 183 received vitamin D. In accordance with the World Health Organization (WHO) clinical progression scale, two studies investigated participants with moderate or severe disease, and one study individuals with mild or asymptomatic disease. The control groups consisted of placebo treatment or standard of care alone. Effectiveness of vitamin D supplementation for people with COVID-19 and moderate to severe disease We included two studies with 313 participants. Due to substantial clinical and methodological diversity of both studies, we were not able to pool data. Vitamin D status was unknown in one study, whereas the other study reported data for vitamin D deficient participants. One study administered multiple doses of oral calcifediol at days 1, 3 and 7, whereas the other study gave a single high dose of oral cholecalciferol at baseline. We assessed one study with low risk of bias for effectiveness outcomes, and the other with some concerns about randomisation and selective reporting. All-cause mortality at hospital discharge (313 participants) We found two studies reporting data for this outcome. One study reported no deaths when treated with vitamin D out of 50 participants, compared to two deaths out of 26 participants in the control group (Risk ratio (RR) 0.11, 95% confidence interval (CI) 0.01 to 2.13). The other study reported nine deaths out of 119 individuals in the vitamin D group, whereas six participants out of 118 died in the placebo group (RR 1.49, 95% CI 0.55 to 4.04]. We are very uncertain whether vitamin D has an effect on all-cause mortality at hospital discharge (very low-certainty evidence). Clinical status assessed by the need for invasive mechanical ventilation (237 participants) We found one study reporting data for this outcome. Nine out of 119 participants needed invasive mechanical ventilation when treated with vitamin D, compared to 17 out of 118 participants in the placebo group (RR 0.52, 95% CI 0.24 to 1.13). Vitamin D supplementation may decrease need for invasive mechanical ventilation, but the evidence is uncertain (low-certainty evidence). Quality of life We did not find data for quality of life. Safety of vitamin D supplementation for people with COVID-19 and moderate to severe disease We did not include data from one study, because assessment of serious adverse events was not described and we are concerned that data might have been inconsistently measured. This study reported vomiting in one out of 119 participants immediately after vitamin D intake (RR 2.98, 95% CI 0.12 to 72.30). We are very uncertain whether vitamin D supplementation is associated with higher risk for adverse events (very low-certainty). Effectiveness and safety of vitamin D supplementation for people with COVID-19 and asymptomatic or mild disease We found one study including 40 individuals, which did not report our prioritised outcomes, but instead data for viral clearance, inflammatory markers, and vitamin D serum levels. The authors reported no events of hypercalcaemia, but recording and assessment of further adverse events remains unclear. Authors administered oral cholecalciferol in daily doses for at least 14 days, and continued with weekly doses if vitamin D blood levels were > 50 ng/mL. AUTHORS' CONCLUSIONS: There is currently insufficient evidence to determine the benefits and harms of vitamin D supplementation as a treatment of COVID-19. The evidence for the effectiveness of vitamin D supplementation for the treatment of COVID-19 is very uncertain. Moreover, we found only limited safety information, and were concerned about consistency in measurement and recording of these outcomes. There was substantial clinical and methodological heterogeneity of included studies, mainly because of different supplementation strategies, formulations, vitamin D status of participants, and reported outcomes. There is an urgent need for well-designed and adequately powered randomised controlled trials (RCTs) with an appropriate randomisation procedure, comparability of study arms and preferably double-blinding. We identified 21 ongoing and three completed studies without published results, which indicates that these needs will be addressed and that our findings are subject to change in the future. Due to the living approach of this work, we will update the review periodically.

ObjectiveVitamin D is critical for calcium and bone metabolism. Vitamin D insufficiency impairs skeletal mineralization and bone growth rate during childhood, thus affecting height and health. Vitamin D status in children with short stature is sparsely reported. The purpose of the current study was to investigate various vitamin D components by high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) to better explore vitamin D storage of short-stature children in vivo.MethodsSerum circulating levels of 25-hydroxyvitamin D2 [25(OH)D2], 25-hydroxyvitamin D3 [25(OH)D3], and 3-epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3, C3-epi] were accurately computed using the LC-MS/MS method. Total 25(OH)D [t-25(OH)D] and ratios of 25(OH)D2/25(OH)D3 and C3-epi/25(OH)D3 were then respectively calculated. Free 25(OH)D [f-25(OH)D] was also measured.Results25(OH)D3 and f-25(OH)D levels in short-stature subgroups 2 (school age: 7~12 years old) and 3 (adolescence: 13~18 years old) were significantly lower compared with those of healthy controls. By contrast, C3-epi levels and C3-epi/25(OH)D3 ratios in all the three short-stature subgroups were markedly higher than the corresponding healthy cases. Based on cutoff values developed by Endocrine Society Recommendation (but not suitable for methods 2 and 3), sufficient storage capacities of vitamin D in short-stature subgroups 1, 2, and 3 were 42.8%, 23.8%, and 9.0% as determined by Method 3 [25(OH)D2/3+25(OH)D3], which were lower than those of 57.1%, 28.6%, and 18.2% as determined by Method 1 [25(OH)D2+25(OH)D3+C3-epi] and 45.7%, 28.5%, and 13.6% as determined by Method 2 [25(OH)D2/3+25(OH)D3+C3-epi]. Levels of 25(OH)D2 were found to be weakly negatively correlated with those of 25(OH)D3, and higher 25(OH)D3 levels were positively correlated with higher levels of C3-epi in both short-stature and healthy control cohorts. Furthermore, f-25(OH)D levels were positively associated with 25(OH)D3 and C3-epi levels in children.ConclusionsThe current LC-MS/MS technique can not only separate 25(OH)D2 from 25(OH)D3 but also distinguish C3-epi from 25(OH)D3. Measurement of t-25(OH)D [25(OH)D2+25(OH)D3] alone may overestimate vitamin D storage in children, and short-stature children had lower vitamin D levels compared with healthy subjects. Ratios of C3-epi/25(OH)D3 and 25(OH)D2/25(OH)D3 might be alternative markers for vitamin D catabolism/storage in short-stature children. Further studies are needed to explore the relationships and physiological roles of various vitamin D metabolites.

Although both vitamin D deficiency and obesity are highly prevalent in the UAE, the role of vitamin D metabolites in mediating obesity-related adverse health effects is not clear. We aimed to assess the role of vitamin D metabolites as potential mediators in the association between obesity, inflammation and metabolic risk factors.277 participants who were part of a randomized controlled trial had their assessment that included clinical, anthropometric and physical activity data at baseline and at 6 months. Blood and urine samples were taken for measurements of serum 25(OH)D, 25(OH)D metabolites including 25(OH)D3), 25(OH)D2), 1,25(OH)2D3, 3-Epi-D3), metabolic and inflammatory markers and related biochemical variables. Multiple regression analysis used to assess the role of 25(OH)D metabolites in mediating the effect of increasing body mass index (BMI) on inflammation and metabolic risk factors.Overall, 277 participants with complete 6 months follow up with a mean (±SD) age of 41 ± 12 and 204 (74%) female were included in the study. Blood pressure, inflammatory, metabolic and lipid profile markers significantly increased in overweight and obese subjects compared to subjects with normal BMI both at baseline and at 6 months (p0.05). 25(OH)D revealed significant association with age, gender, HbA1c and type 2 diabetes (p0.05). No statistically significant changes in any of 25(OH)D metabolites assessed. Multivariate analysis revealed significant and independent associations between BMI and important inflammatory and metabolic risk factors (p0.05). No similar association observed with 25(OH)D metabolites.Although we found significant association between 25(OH)D and prevalence of type 2 diabetes, we found no evidence however to support a role of 25(OH)D metabolites in mediating the effect of BMI on inflammatory or metabolic risk factors.

Objective GC/DBP effects on response to vitamin D supplementation have not been well-studied. Thus we assessed free and total 25-OHD after vitamin D treatment across the six common GC haplotypes. Design This double-blind, randomized study compared two vitamin D3 doses in healthy, urban-dwelling 6-month to 10-year-old children at-risk for vitamin D deficiency. Randomization was stratified by GC haplotype. Methods Children were randomized to receive 2800 or 7000 International Units of vitamin D3 weekly. 25-OHD and 1,25(OH)2D were sampled at baseline and after 1–6 months of supplementation. Results and conclusions One hundred ninety-two of 225 enrolled subjects completed the study. After one month, total 25-OHD increased with both doses and were higher with 7000 IU/week (85.5 ± 22.8 nmol/L) compared to 2800 IU/week (76.8 ± 18.0 nmol/L), despite equivalent baseline levels. No further significant increase occurred at 6 months (89.8 ± 35.5 and 74.3 ± 18.3 nmol/L, respectively). Free 25-OHD similarly changed. 25-OHD differed among GC groups at baseline. Although no significant effects of individual GC haplotypes on incremental changes were evident, a trend toward an effect of combined 'at risk' GC alleles on response was evident (P = 0.06). Total 1,25(OH)2D showed modest increases, moreso with the larger dose. In urban-dwelling children at-risk for vitamin D deficiency, 1 month of vitamin D3 2800 IU/week increased 25-OHD across all GC haplotype groups, and somewhat enhanced with 7000 IU/week with no further significant increases after 6 months of supplementation. Free 25-OHD measures offer no monitoring advantage over total 25-OHD.