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

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 were analyzed 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 American Pathologists 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 to choose appropriate reference materials and select proficiency or external quality assessment programs and will serve as a foundation for additional VDSP studies.

Accuracy-Based Vitamin D Survey: Six Years of Quality Improvement Guided by Proficiency Testing

“…2019;143:1531-1538; doi: 10.5858/arpa.2018-0625-CP) V itamin D measurement techniques and proper utilization have been a source of interesting debate in the laboratory medicine community for quite some time. [1][2][3][4][5][6][7][8][9][10] Vitamin D is made up of several fat-soluble secosteroids. 11,12 The 2 major forms of vitamin D are vitamin D 2 or ergocalciferol, which is derived from plants, and vitamin D 3 or cholecalciferol, which is derived from animal sources.…”

Early prenatal use of a multivitamin diminishes the risk for inadequate vitamin D status in pregnant women: results from the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort study

“…Plasma samples collected during the first and third trimester visits and at delivery ( 17 ) were used to measure 25OHD and categorize participants as having concentrations <30, <40, <50, and 50–125 nmol/L; we also categorized plasma 25OHD >125 nmol/L to explore concentrations at which there may be concern for adverse effects ( 1 ). Two methods were used to measure maternal plasma 25OHD, and results were standardized according to standard reference materials ( 12 , 13 ). Initially, plasma 25OHD (first trimester: n = 1188; third trimester: n = 762; and delivery: n = 656) was measured using Total 25-hydroxyvitamin D immunoassay kits and the LIAISON autoanalyzer platform (Diasorin Inc.), as previously described ( 3 ).…”

“…To the best of our knowledge, no pregnancy study in Canada has reported on the recommended population cut point of serum 25OHD ≥40 nmol/L ( 1 ). In addition, the majority of reports predate the launch of the Vitamin D Standardization Certification Program (VDSCP) ( 12 , 13 ). The VDSCP aims to improve the accuracy and comparability of 25OHD measurements across assays and laboratories around the world.…”

Harmonization of Liquid Chromatography–Tandem Mass Spectrometry Protein Assays

“…1–3 represent an aspirational goal for fully harmonized and/or standardized methods, although relatively few methods in clinical chemistry have completed this rigorous process to date, and to our knowledge no routine MS-based methods are among these fully harmonized or standardized methods, although in the small-molecule realm, significant progress toward that goal has been made by laboratories that have voluntarily participated in the Centers for disease Control and Prevention’s (CDC’s) Hormone Standardization (HoSt) Program 3 and Vitamin D Standardization-Certification Program (VDSCP). 4…”

“…Included among the harmonization success stories to date are efforts such as the CDC’s HoSt program, which is focused on serum hormones like thyroid-stimulating hormone, 21 estradiol and, testosterone, 22 and the NIH/Office of Dietary Supplements Vitamin D Standardization Program. 4,23 Other organizations have also led efforts to create international standards for measurands like serum immunoglobulin E 24 (College of American Pathologists (CAP), WHO), free thyroxine, 25 triiodothyronine 26 (IFCC), and for lipid function tests such as cholesterol 27 (NIST), and kidney function measurement of serum creatinine 28 (NIST). In some cases, atypically, harmonization of clinical assays results from only a single manufacturer producing a test specific for a given measurand (N terminal-proBNP, cardiac troponin T) 5,29 (Roche Diagnostics, Risch-Rotkreuz, Switzerland).…”