Assessment of serum total 25-hydroxyvitamin D assay commutability of Standard Reference Materials and College of American Pathologists Accuracy-Based Vitamin D (ABVD) Scheme and Vitamin D External Quality Assessment Scheme (DEQAS) materials: Vitamin D Standardization Program (VDSP) Commutability Study 2

Abstract Until recently, the Vitamin D External Quality Assessment Scheme (DEQAS) assessed the performance of various assays for the determination of serum total 25-hydroxyvitamin D [25(OH)D] by using a consensus mean based on the all-laboratory trimmed mean (ALTM) of the approximately 1000 participants' results. Since October 2012, the National Institute of Standardsand Technology (NIST), as part of the Vitamin D Standardization Program, has participated in DEQAS by analyzing the quarterly serum sample sets using an isotope dilution LC-tandem MS (ID LC-MS/MS) reference measurement procedure to assign an accuracy-based target value for serum total 25(OH)D. NIST has analyzed90 DEQAS samples (18 exercises × 5 samples/exercise) to assign target values. The NIST-assigned values are compared with the ALTM and the biases assessed for various assays used by the participants, e.g., LC-MS/MS, HPLC, and several ligand-binding assays. The NIST-value assignment process and the resultsof the analyses of the 90 DEQAS samples are summarized. The absolute mean bias between the NIST-assignedvalues and the ALTM was 5.6%, with 10% of the samples having biases >10%. Benefits of the accuracy-based target values are presented, including for sample sets with high concentrations of 25(OH)D2 and 3-epi-25(OH)D3.

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Baseline Assessment of 25-Hydroxyvitamin D Reference Material and Proficiency Testing/External Quality Assurance Material Commutability: A Vitamin D Standardization Program Study

Journal of AOAC International ◽

10.5740/jaoacint.17-0291 ◽

2017 ◽

Vol 100 (5) ◽

pp. 1288-1293 ◽

Cited By ~ 5

Author(s):

Karen W Phinney ◽

Christopher T Sempos ◽

Susan S-C Tai ◽

Johanna E Camara ◽

Stephen A Wise ◽

...

Keyword(s):

Vitamin D ◽

Quality Assurance ◽

Reference Material ◽

Quality Assessment ◽

Human Serum ◽

Proficiency Testing ◽

External Quality Assessment ◽

External Quality ◽

Hydroxyvitamin D ◽

25 Hydroxyvitamin D

Abstract The Vitamin D Standardization Program (VDSP) coordinated a study in 2012 to assess the commutability of reference materials and proficiency testing/external quality assurance materials for total 25-hydroxyvitamin D [25(OH)D] in human serum, the primary indicator of vitamin D status. A set of 50 single-donor serum samples as well as 17 reference and proficiency testing/external quality assessment materials wereanalyzed by participating laboratories that used either immunoassay or LC-MS methods for total 25(OH)D. The commutability test materials included National Institute of Standards and Technology Standard Reference Material 972a Vitamin D Metabolites in Human Serum as well as materials from the College of AmericanPathologists and the Vitamin D External Quality Assessment Scheme. Study protocols and data analysis procedures were in accordance with Clinical and Laboratory Standards Institute guidelines. The majority of the test materials were found to be commutable with the methods used in this commutability study. These results provide guidance for laboratories needing tochoose appropriate reference materials and select proficiency or external quality assessment programs and will serve as a foundation for additional VDSP studies.

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Reference materials and analytical standards to stimulate improved laboratory performance: Experience from the external quality assessment scheme for trace elements in biological samples

Microchimica Acta ◽

10.1007/bf01244398 ◽

1996 ◽

Vol 123 (1-4) ◽

pp. 251-260 ◽

Cited By ~ 3

Author(s):

Andrew Taylor

Keyword(s):

Trace Elements ◽

Quality Assessment ◽

Reference Materials ◽

Biological Samples ◽

External Quality Assessment ◽

External Quality ◽

External Quality Assessment Scheme ◽

Laboratory Performance ◽

Analytical Standards

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Findings of an external quality assessment scheme for determining aluminum in dialysis fluids and water

Clinical Chemistry ◽

10.1093/clinchem/40.8.1517 ◽

1994 ◽

Vol 40 (8) ◽

pp. 1517-1521 ◽

Cited By ~ 7

Author(s):

A Taylor ◽

R J Briggs ◽

C Cevik

Keyword(s):

Quality Assessment ◽

Reference Materials ◽

Significant Influence ◽

Matrix Effects ◽

External Quality Assessment ◽

Analytical Performance ◽

External Quality ◽

External Quality Assessment Scheme ◽

Dialysis Fluids

Abstract The analytical performance of laboratories participating in the dialysis fluids and water aluminum program of the Guildford External Quality Assessment Scheme over the period 1986-1993 has been reviewed. For aluminum concentrations > 3.33 mumol/L in dialysis fluids, the between-laboratory CV has fallen from approximately 36% to 23%, whereas for specimens of water the reduction was from 36% to approximately 18%. Improvements at lower concentrations were less impressive. Performance of individual participants varied; only a few consistently provided accurate results. Many of the participants are able to measure serum aluminum well, so lack of expertise is not responsible for poor results. We suggest that matrix effects associated with different specimen types have a significant influence on performance and that due account is not always taken of these factors. Resolution of these problems would be aided by appropriate reference materials.

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