Establishing an Accuracy Basis for the Vitamin D External Quality Assessment Scheme (DEQAS)

Burdette, Carolyn Q.; Camara, Johanna E.; Nalin, Federica; Pritchett, Jeanita S.; Sander, Lane C.; Carter, Graham D.; Jones, Julia C.; Betz, Joseph M.; Sempos, Christopher T.; Wise, Stephen A.

doi:10.5740/jaoacint.17-0306

Cited by 43 publications

(39 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…US National Institute for Standards and Technology (NIST) [8]] and the introduction of The Vitamin D Standardization Program (VDSP) has it been possible to evaluate assay variation in an unbiased way [9]. This led to converting DEQAS [10] to an accuracy-based survey where standardized target values were assigned to serum samples using NIST reference measurement procedures [10]. Recent data from DEQAS have shown that such unstandardized assays are subject to significant assay variation over time [11,12].…”

Section: Vitamin D Assay Standardization: An Updatementioning

confidence: 99%

Consensus statement from 2nd International Conference on Controversies in Vitamin D

Giustina

Adler

Binkley

et al. 2020

Rev Endocr Metab Disord

224

169

View full text Add to dashboard Cite

The 2 nd International Conference on Controversies in Vitamin D was held in Monteriggioni (Siena), Italy, September 11-14, 2018. The aim of this meeting was to address ongoing controversies and timely topics in vitamin D research, to review available data related to these topics and controversies, to promote discussion to help resolve lingering issues and ultimately to suggest a research agenda to clarify areas of uncertainty. Several issues from the first conference, held in 2017, were revisited, such as assays used to determine serum 25-hydroxyvitamin D [25(OH)D] concentration, which remains a critical and controversial issue for defining vitamin D status. Definitions of vitamin D nutritional status (i.e. sufficiency, insufficiency and deficiency) were also revisited. New areas were reviewed, including vitamin D threshold values and how they should be defined in the context of specific diseases, sources of vitamin D and risk factors associated with vitamin D deficiency. Non-skeletal aspects related to vitamin D were also discussed, including the reproductive system, neurology, chronic kidney disease and falls. The therapeutic role of vitamin D and findings from recent clinical trials were also addressed. The topics were considered by 3 focus groups and divided into three main areas: 1) "Laboratory": assays and threshold values to define vitamin D status; 2) "Clinical": sources of vitamin D and risk factors and role of vitamin D in non-skeletal disease and 3) "Therapeutics": controversial issues on observational studies and recent randomized controlled trials. In this report, we present a summary of our findings.

show abstract

Section: Vitamin D Assay Standardization: An Updatementioning

confidence: 99%

Consensus statement from 2nd International Conference on Controversies in Vitamin D

Giustina

Adler

Binkley

et al. 2020

Rev Endocr Metab Disord

224

169

View full text Add to dashboard Cite

show abstract

“…Similar to 25(OH)D 2 , 24,25(OH) 2 D 3 , has a different mass to 25(OH)D 3 and poses no threat to the reliability of LC-MS/MS methods [ 67 ]. Epi-25(OH)D, the result of epimerisation of 25(OH)D, with levels that are highest in neonates up to one year of age and present in most adults at about 9% of 25(OH)D, does not influence the results of immunoassays, as antibodies do not recognise it [ 61 , 69 , 70 ]. Many LC-MS/MS assays, on the other hand, experience difficulties distinguishing the two epimers due to their equal mass and their similar affinity for most LC columns, resulting in an overestimation, and potential misclassification, of total 25(OH)D [ 61 , 69 , 71 , 72 ].…”

Section: How: Importance Of the Choice Of Methodsmentioning

confidence: 99%

“…Epi-25(OH)D, the result of epimerisation of 25(OH)D, with levels that are highest in neonates up to one year of age and present in most adults at about 9% of 25(OH)D, does not influence the results of immunoassays, as antibodies do not recognise it [ 61 , 69 , 70 ]. Many LC-MS/MS assays, on the other hand, experience difficulties distinguishing the two epimers due to their equal mass and their similar affinity for most LC columns, resulting in an overestimation, and potential misclassification, of total 25(OH)D [ 61 , 69 , 71 , 72 ]. Several LC-MS/MS assays now use non-C18 columns enabling them to chromatographically separate the epimer and measure it independently of 25(OH)D, despite the identical masses [ 45 , 68 , 73 , 74 , 75 , 76 ].…”

Section: How: Importance Of the Choice Of Methodsmentioning

confidence: 99%

The When, What & How of Measuring Vitamin D Metabolism in Clinical Medicine

et al. 2018

View full text Add to dashboard Cite

We now have the ability to measure a number of different vitamin D metabolites with very accurate methods. The most abundant vitamin D metabolite, 25-hydroxyvitamin D, is currently the best marker for overall vitamin D status and is therefore most commonly measured in clinical medicine. The added value of measuring metabolites beyond 25-hydroxyvitamin D, like 1,25-, and 24,25-dihydroxyvitamin D is not broadly appreciated. Yet, in some more complicated cases, these metabolites may provide just the information needed for a legitimate diagnosis. The problem at present, is knowing when to measure, what to measure and how to measure. For 25-hydroxyvitamin D, the most frequently used automated immunoassays do not meet the requirements of today’s standards for certain patient groups and liquid chromatography-tandem mass spectrometry is the desired method of choice in these individuals. The less frequently measured 1,25-dihydroxyvitamin D metabolite enables us to identify a number of conditions, including 1α-hydroxylase deficiency, hereditary vitamin D-resistant rickets and a number of granulomatous diseases or lymphoproliferative diseases accompanied by hypercalcaemia. Furthermore, it discriminates between the FGF23-mediated and non-FGF23-mediated hypophosphatemic syndromes. The 24,25-dihydroxyvitamin D metabolite has proven its value in the diagnosis of idiopathic infantile hypercalcaemia and has the potential of having value in identifying other diseases. For both metabolites, the understanding of the origin of differences between assays is limited and requires further attention. Nonetheless, in every way, appropriate measurement of vitamin D metabolism in the clinical laboratory hinges eminently on the comprehension of the value of the different metabolites, and the importance of the choice of method.

show abstract

“…Quality of the assay was assured by participation in the Vitamin D External Quality Assessment Scheme. 23 The fatty acid composition after hydrolysis of erythrocytes was analyzed with a slightly modified version of a method that was previously reported. 24 Fifty microliters of erythrocytes was first transmethylated to fatty acid methyl esters in 2 mol/L KOH in methanol.…”

Section: Methodsmentioning

confidence: 99%

The influence of disease severity and lifestyle factors on the peak annual 25(OH)D value of COPD patients

Kentson

Leanderson

Jacobson³

et al. 2018

COPD

View full text Add to dashboard Cite

BackgroundThe prevalence of individuals deficient in vitamin D (defined as a serum level of the stable metabolite 25(OH)D <50 nmol/L) is increasing in countries with low annual ultraviolet (UV) radiation and among individuals unable to perform outdoor activities, for example, COPD patients.ObjectiveTo assess the role of vitamin D deficiency, independently of seasonal variation, the peak annual value of 25(OH)D was measured in subjects with advanced COPD ± long-term oxygen therapy (LTOT) and lung healthy control subjects. A method to grade the individual annual UV light exposure was designed and tested.Subjects and methodsSixty-six Caucasians with advanced COPD (28 with LTOT) and 47 control subjects were included, and the levels of 25(OH)D were determined in late summer/early fall when the annual peak was assumed. Questionnaires about COPD symptoms, general health, lifestyle, dietary habits and QoL were used to collect data. Lung function tests and blood sampling were performed.ResultsThe peak annual 25(OH)D of COPD subjects was significantly lower than in the control subjects, but there was no significant difference between COPD patients with and without LTOT. Ongoing vitamin D supplementation was the single most important intervention to maintain 25(OH)D levels ≥50 nmol/L. Among vitamin D-deficient COPD subjects, 25(OH) D correlated positively with forced expiratory volume in 1 second as % predicted, Modified British Medical Research Council score, blood oxygenation, food portion size, Mediterranean Diet Score and Ultraviolet Score.ConclusionVitamin D deficiency was common among healthy individuals and COPD subjects. Peak annual 25(OH)D levels of COPD subjects correlated with clinically important outcomes. The present study emphasizes the need to routinely monitor vitamin D status among patients with advanced COPD and to consider to medicate those with vitamin D deficiency with vitamin D supplementation.

show abstract

Establishing an Accuracy Basis for the Vitamin D External Quality Assessment Scheme (DEQAS)

Cited by 43 publications

References 0 publications

Consensus statement from 2nd International Conference on Controversies in Vitamin D

Consensus statement from 2nd International Conference on Controversies in Vitamin D

The When, What & How of Measuring Vitamin D Metabolism in Clinical Medicine

The influence of disease severity and lifestyle factors on the peak annual 25(OH)D value of COPD patients

Contact Info

Product

Resources

About