Concordance between direct and indirect measurements of free 25-OH vitamin D

Peris, Pilar; Filella, Xavier; Monegal, Ana; Guañabens, Núria; Foj, Laura; Bonet, María Luisa; Boquet, D.; Casado, Enrique; Cerdá, Dacia; Erra, Alba; Gómez-Vaquero, Carmen; González-Martínez, Silvia; Montalà, Núria; Pittarch, Concepción; Kanterewicz, Eduardo; Sala, Miquel; Surís, Xavier

doi:10.1016/j.cca.2017.10.016

Cited by 9 publications

(6 citation statements)

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“…The allele frequencies obtained were comparable to those from genotyping [ 32 ]. Directly measured 25OHD Free levels correlated well with the calculated levels, but the measured 25OHD Free levels were significantly lower than the calculations, as in previous reports [ 21 , 33 ]. These differences may reflect the lack of 25OHD Free measurement standardization.…”

Section: Discussionsupporting

confidence: 85%

Total, bioavailable and free 25-hydroxyvitamin D levels as functional indicators for bone parameters in healthy children

Heo

Lee

et al. 2021

PLoS ONE

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Objectives Vitamin D is essential for bone health. Not only total but also free 25-hydroxyvitamin D (25OHD) may contribute to bone mass. We sought to determine which vitamin D measure best reflected clinical and bone parameters in healthy children. Methods A cross-sectional study including 146 healthy children (71 boys, 9.5 ± 1.9 years) conducted at a tertiary medical center. We used a multiplex liquid chromatography-tandem mass spectrometry-based assay to simultaneously measure vitamin D metabolites. The bioavailable and free 25OHD (25OHDBioA and 25OHDFree) levels were calculated using the genotype-specific or genotype-constant affinity coefficients of vitamin D-binding proteins (yielding spe-25OHDBioA, spe-25OHDFree and con-25OHDBioA, con-25OHDFree respectively). The 25OHDFree level was directly measured (m-25OHDFree). Bone mineral content (BMC) and bone mineral density (BMD) were assessed via dual-energy X-ray absorptiometry. Results The total 25OHD (25OHDTotal), the two forms of 25OHDBioA, the three forms of 25OHDFree, and 24,25-dihydroxyvitamin D3 levels correlated with parathyroid hormone level (all p < 0.01). Serum 25OHDTotal and m-25OHDFree levels were influenced by age, pubertal status, season, body mass index (BMI), daylight hours, and vitamin D intake (all p < 0.05). The con-25OHDBioA and con-25OHDFree levels better reflected pubertal status and daylight hours than did the spe-25OHDBioA and spe-25OHDFree levels (both p < 0.01). The association between the 25OHDTotal level and bone parameters varied according to the BMI (interaction p < 0.05). In 109 normal-weight children, the con-25OHDBioA and con-25OHDFree levels correlated with total body BMC and BMD (both p < 0.05), whereas the 25OHDTotal and 24,25-dihydroxyvitamin D3 levels were associated with total body BMC (both p < 0.05). No such association was found in overweight or obese children. Conclusions In healthy children, total, bioavailable, and free 25OHD levels comparably reflected lifestyle factors. In normal-weight children, the con-25OHDBioA and con-25OHDFree, but not m-25OHDFree levels, reflected bone mass, as did the 25OHDTotal level.

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Section: Discussionsupporting

confidence: 85%

Total, bioavailable and free 25-hydroxyvitamin D levels as functional indicators for bone parameters in healthy children

Heo

Lee

et al. 2021

PLoS ONE

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“…The aforementioned studies had calculated the free vitamin D levels by using the formula rather than direct measurement [22]. It has been shown that there is a concordance between directly measured vs. calculated free vitamin D levels as well as has a dependent bias of concentration suggesting that the direct measure of free vitamin D concentrations could be a better option than the calculated one [23]. In another study, directly measured free vitamin D concentrations were related to parathyroid hormone (PTH) and calcium, but calculated estimates were not.…”

Section: Discussionmentioning

confidence: 99%

Free vitamin D correlate better with bone mineral density and thoracolumbar junction osteoporotic vertebral fractures than serum vitamin D

Chhantyal

et al. 2020

BMC Musculoskelet Disord

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Background: Vitamin D deficiency has long been studied as a risk factor for osteoporosis. However, the association between serum vitamin D status, bone mineral density (BMD) and the incidence of vertebral fractures (OVFs) remain controversial. It is believed that free portion of the circulating vitamin D carries the metabolic activities of vitamin D. Therefore, the aim of the present study is to analyse if free vitamin D correlates with BMD and osteoporotic fragile vertebral fractures in the elderly population.Methods: A total of 90 consecutive patients, including 81 female and 9 male patients, aged > 48 years, were included in this cross sectional study between March and July of 2018. Total vitamin D (total 25(OH)D), free vitamin D (free 25(OH)D), calcium and phosphorus were measured. BMD was measured using dual energy X-ray absorptiometry (DEXA) and osteoporotic vertebral fracture was assessed using plain radiograph. Multiple linear regression was performed to find out the association between total vitamin D, free vitamin D and BMD at various sites. To evaluate the association with osteoporotic vertebral multivariate logistic regression model was used.Results: The mean total vitamin D and free vitamin D were 25.1 ± 10.2 and 6.1 ± 1.7 respectively. Free vitamin D had a linear correlation with total vitamin D (R 2 = 0.69). While free vitamin D had a positive correlation with lumbar BMD roles (p < 0.05), total vitamin D didn't have any association with BMD at any site. Of the total patients, 62 patients (68.9%) had thoracolumbar junction OVFs. Free vitamin D level correlated with the prevalence of OVFs as well as lumbar osteoporosis (p < 0.05). However, there was no statistical correlation between serum vitamin D status and the OVFs. Conclusions: Free vitamin D was significantly related to the occurrence of thoracolumbar junction OVFs and lumbar BMD, which assumed to be a positive predictor for fracture and osteoporosis prevention. However, total serum vitamin D levels did not have any association with BMD at different sites as well as fragile vertebral fracture. Trial registration: The study is registered at clinicaltrials.gov NCT03605173.

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“…However, this method is highly complex and expensive. A recently marketed ELISA from DiaSource showed good agreement with a dialysis-based reference method [213], but low concordance with indirect methods [211,214]. Amongst 173 healthy women, Deming's regression showed a slope of 0.3 ± 0.03, and a correlation coefficient of 0.6 ± 0.06.…”

Section: Analytical Considerationsmentioning

confidence: 97%

“…However, VDBP was measured by a monoclonal immunoassay that suffers from variable detection of different VDBP variants. In 173 healthy women, Peris et al reported free 25(OH)D concentrations between 2 and 15 pg/ml using an indirect method whereas directly measured results ranged between 2 and 8 pg/ml [214]. Zeng et al determined normal free 25(OH)D results on the basis of sufficient total 25(OH)D concentrations and suggested a range between 8.5 and 28.3 pg/ml (equivalent to 30 and 100 ng/ml of total 25(OH)D [74].…”

Section: Expected Valuesmentioning

confidence: 99%

Vitamin D Metabolites: Analytical Challenges and Clinical Relevance

et al. 2022

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Recent research activities have provided new insights in vitamin D metabolism in various conditions. Furthermore, substantial progress has been made in the analysis of vitamin D metabolites and related biomarkers, such as vitamin D binding protein. Liquid chromatography tandem mass spectrometric (LC–MS/MS) methods are capable of accurately measuring multiple vitamin D metabolites in parallel. Nevertheless, only 25(OH)D and the biologically active form 1,25(OH)2D are routinely measured in clinical practice. While 25(OH)D remains the analyte of choice for the diagnosis of vitamin D deficiency, 1,25(OH)2D is only recommended in a few conditions with a dysregulated D metabolism. 24,25(OH)2D, free and bioavailable 25(OH)D, and the vitamin D metabolite ratio (VMR) have shown promising results, but technical pitfalls in their quantification, limited clinical data and the lack of reference values, impede their use in clinical practice. LC–MS/MS is the preferred method for the measurement of all vitamin D related analytes as it offers high sensitivity and specificity. In particular, 25(OH)D and 24,25(OH)2D can accurately be measured with this technology. When interpreted together, they seem to provide a functional measure of vitamin D metabolism beyond the analysis of 25(OH)D alone. The determination of VDBP, free and bioavailable 25(OH)D is compromised by unresolved analytical issues, lacking reference intervals and insufficient clinical data. Therefore, future research activities should focus on analytical standardization and exploration of their clinical value. This review provides an overview on established and new vitamin D related biomarkers including their pathophysiological role, preanalytical and analytical aspects, expected values, indications and influencing conditions.

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Concordance between direct and indirect measurements of free 25-OH vitamin D

Cited by 9 publications

References 9 publications

Total, bioavailable and free 25-hydroxyvitamin D levels as functional indicators for bone parameters in healthy children

Total, bioavailable and free 25-hydroxyvitamin D levels as functional indicators for bone parameters in healthy children

Free vitamin D correlate better with bone mineral density and thoracolumbar junction osteoporotic vertebral fractures than serum vitamin D

Vitamin D Metabolites: Analytical Challenges and Clinical Relevance

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