The vitamin D External Quality Assessment Scheme (DEQAS) for 25-hydroxyvitamin D (25-OHD) has approximately 1100 participants in 53 countries using 26 different methods or variants of methods (October 2014). In April 2015, the scheme was extended to cover 24,25-dihydroxyvitamin D. (24,25 (OH)(2)D). Since 2013, the 25-OHD scheme has been accuracy-based with values assigned by the NIST reference measurement procedure (RMP). DEQAS is uniquely placed to assess the accuracy (bias) and specificity of 25-OHD methods in a routine laboratory setting. Other vitamin D metabolites are known to interfere in 25-OHD assays and DEQAS has distributed samples spiked with 3-epi-25-OHD3 (52.4 nmol/L), 24R,25(OH)(2)D-3 (14.4 nmol/L) and 245,25(OH)(2)D-3 (57.9 nmol/L). The 3-epimer showed a cross reactivity of 56% in a competitive protein binding assay but was not detected in any antibody-based methods. Not all HPLC/UV or LC-MS/MS methods were able to resolve 3-epi-25-OHD3 from 25-OHD3 and thus overestimated total 25-OHD:The cross reactivity of 24R,25(OH)(2)D-3 (245,25(OH)(2)D-3) ranged from <5% (<5%) to 548% (643%) in ligand binding assays. Both 24-hydroxylated metabolites were resolved by HPLC/UV and LC-MS/MS methods and thus caused no complications in the measurement of 25-OHD. Most antibodies to 25-OHD are known to cross-react with dihydroxylated metabolites but interference in some assays was far greater than expected. This may be related to the anomalous behaviour of exogenously added metabolites in these 25-OHD methods. (C) 2015 Elsevier Ltd. All rights reserved.
机构:Univ Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Strathmann, Frederick G.
;
Sadilkova, Katerina
论文数: 0引用数: 0
h-index: 0
机构:
Seattle Childrens Hosp Lab, Dept Lab Med, Seattle, WA 98105 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Sadilkova, Katerina
;
Laha, Thomas J.
论文数: 0引用数: 0
h-index: 0
机构:Univ Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Laha, Thomas J.
;
LeSourd, Susan E.
论文数: 0引用数: 0
h-index: 0
机构:
Univ Arkansas Med Sci, Dept Pathol, Little Rock, AR 72201 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
LeSourd, Susan E.
;
Bornhorst, Joshua A.
论文数: 0引用数: 0
h-index: 0
机构:
Univ Arkansas Med Sci, Dept Pathol, Little Rock, AR 72201 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Bornhorst, Joshua A.
;
Hoofnagle, Andrew N.
论文数: 0引用数: 0
h-index: 0
机构:
Univ Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Univ Washington, Dept Med, Seattle, WA 98195 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Hoofnagle, Andrew N.
;
Jack, Rhona
论文数: 0引用数: 0
h-index: 0
机构:
Seattle Childrens Hosp Lab, Dept Lab Med, Seattle, WA 98105 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
机构:Univ Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Strathmann, Frederick G.
;
Sadilkova, Katerina
论文数: 0引用数: 0
h-index: 0
机构:
Seattle Childrens Hosp Lab, Dept Lab Med, Seattle, WA 98105 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Sadilkova, Katerina
;
Laha, Thomas J.
论文数: 0引用数: 0
h-index: 0
机构:Univ Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Laha, Thomas J.
;
LeSourd, Susan E.
论文数: 0引用数: 0
h-index: 0
机构:
Univ Arkansas Med Sci, Dept Pathol, Little Rock, AR 72201 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
LeSourd, Susan E.
;
Bornhorst, Joshua A.
论文数: 0引用数: 0
h-index: 0
机构:
Univ Arkansas Med Sci, Dept Pathol, Little Rock, AR 72201 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Bornhorst, Joshua A.
;
Hoofnagle, Andrew N.
论文数: 0引用数: 0
h-index: 0
机构:
Univ Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Univ Washington, Dept Med, Seattle, WA 98195 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA
Hoofnagle, Andrew N.
;
Jack, Rhona
论文数: 0引用数: 0
h-index: 0
机构:
Seattle Childrens Hosp Lab, Dept Lab Med, Seattle, WA 98105 USAUniv Washington, Med Ctr, Dept Lab Med, Seattle, WA 98195 USA