Michael E Rybak1, Ram B Jain, Christine M Pfeiffer. 1. Inorganic Toxicology and Nutrition Branch, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
Abstract
BACKGROUND: Recent investigations into the role vitamin B(6) plays in reducing risk of stroke and cardiovascular disease have heightened interest in vitamin B(6) intake and its relationship to clinical status indicators. Because a true reference method and certified reference materials are lacking, little is known about the relative analytical performance of clinical vitamin B(6) assays. METHODS: Ten laboratories experienced in clinical vitamin B(6) analysis participated in a 3-day analysis of 69 serum and 3 aqueous specimens for pyridoxal 5'-phosphate (PLP). Laboratories used either HPLC-based or enzymatic assays. Results were analyzed for imprecision, recovery, and bias relative to consensus means. RESULTS: Among laboratories, mean within-day CVs (3 specimens x 3 measurements/day) were 0.6%-37% and between-day CVs (20 specimens x 1 measurement/day x 3 days) were 1.4%-26%. Mean recoveries of added PLP were 53%-144%, and mean sample pool mixing recoveries were 75%-119%. Consensus means calculated for 20 serum specimens gave mean relative biases between measurement of -10.0% to 24.3% among participating laboratories over a range of 15.8-319 nmol/L PLP. Measurement imprecision and biases were evaluated against empirically derived performance criteria based on biological variation. Three of 10 laboratories met optimum imprecision requirements and had 90% or more of measurements satisfy optimum criteria for biases among methods. All 10 laboratories met minimum imprecision requirements, but 25%-53% of the results reported by 4 of the 7 suboptimal laboratories failed to satisfy the minimum criteria for bias. CONCLUSION: Agreement among vitamin B(6) methods is good, but large differences in laboratory proficiency exist, pointing to the need for vitamin B(6) reference materials and external quality assurance programs.
BACKGROUND: Recent investigations into the role vitamin B(6) plays in reducing risk of stroke and cardiovascular disease have heightened interest in vitamin B(6) intake and its relationship to clinical status indicators. Because a true reference method and certified reference materials are lacking, little is known about the relative analytical performance of clinical vitamin B(6) assays. METHODS: Ten laboratories experienced in clinical vitamin B(6) analysis participated in a 3-day analysis of 69 serum and 3 aqueous specimens for pyridoxal 5'-phosphate (PLP). Laboratories used either HPLC-based or enzymatic assays. Results were analyzed for imprecision, recovery, and bias relative to consensus means. RESULTS: Among laboratories, mean within-day CVs (3 specimens x 3 measurements/day) were 0.6%-37% and between-day CVs (20 specimens x 1 measurement/day x 3 days) were 1.4%-26%. Mean recoveries of added PLP were 53%-144%, and mean sample pool mixing recoveries were 75%-119%. Consensus means calculated for 20 serum specimens gave mean relative biases between measurement of -10.0% to 24.3% among participating laboratories over a range of 15.8-319 nmol/L PLP. Measurement imprecision and biases were evaluated against empirically derived performance criteria based on biological variation. Three of 10 laboratories met optimum imprecision requirements and had 90% or more of measurements satisfy optimum criteria for biases among methods. All 10 laboratories met minimum imprecision requirements, but 25%-53% of the results reported by 4 of the 7 suboptimal laboratories failed to satisfy the minimum criteria for bias. CONCLUSION: Agreement among vitamin B(6) methods is good, but large differences in laboratory proficiency exist, pointing to the need for vitamin B(6) reference materials and external quality assurance programs.
Authors: Josiane Steluti; Christina Reginaldo; Jacob Selhub; Ligi Paul; Regina Mara Fisberg; Dirce Maria Marchioni Journal: Eur J Nutr Date: 2018-11-02 Impact factor: 5.614
Authors: Josiane Steluti; Aline M Carvalho; Antonio A F Carioca; Andreia Miranda; Gilka J F Gattás; Regina M Fisberg; Dirce M Marchioni Journal: Nutrients Date: 2017-05-25 Impact factor: 5.717
Authors: Øivind Midttun; Despoina Theofylaktopoulou; Adrian McCann; Anouar Fanidi; David C Muller; Klaus Meyer; Arve Ulvik; Wei Zheng; Xiao-Ou Shu; Yong-Bing Xiang; Ross Prentice; Cynthia A Thomson; Mary Pettinger; Graham G Giles; Allison Hodge; Qiuyin Cai; William J Blot; Jie Wu; Mikael Johansson; Johan Hultdin; Kjell Grankvist; Victoria L Stevens; Marjorie L McCullough; Stephanie J Weinstein; Demetrius Albanes; Arnulf Langhammer; Kristian Hveem; Marit Næss; Howard D Sesso; J Michael Gaziano; Julie E Buring; I-Min Lee; Gianluca Severi; Xuehong Zhang; Jiali Han; Meir J Stampfer; Stephanie A Smith-Warner; Anne Zeleniuch-Jacquotte; Loic le Marchand; Jian-Min Yuan; Lesley M Butler; Woon-Puay Koh; Renwei Wang; Yu-Tang Gao; Ulrika Ericson; Emily Sonestedt; Regina G Ziegler; Neal D Freedman; Kala Visvanathan; Miranda R Jones; Caroline Relton; Paul Brennan; Mattias Johansson; Per M Ueland Journal: Am J Clin Nutr Date: 2017-04-19 Impact factor: 7.045