{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,8]],"date-time":"2026-11-08T10:33:57Z","timestamp":1794134037404,"version":"4.8.0"},"reference-count":23,"publisher":"Walter de Gruyter GmbH","issue":"11","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,26]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec id=\"j_cclm-2026-0658_abs_001\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Prompt diagnosis and treatment of vitamin B12 deficiency prevents haematological, neurological, psychological and psychiatric disturbances. During November 2024, reference interval data used for the clinical interpretation of total B12 assays was collated from participants of the UK NEQAS for Haematinic Assays Scheme. From these data we characterised the geographical variation in diagnostic thresholds across the United\u00a0Kingdom to identify regions with poor adherence to National Institute for Health and Care Excellence (NICE) guidance (NG239).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_cclm-2026-0658_abs_002\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Applied diagnostic thresholds for total B12 were collated from scheme participants and summarised. Because of the reported negative analytical bias of the Beckman DxI total B12 assay in comparison to total B12 assays from Abbott, Roche and Siemens, assay compatibility with NG239 was assessed by deriving a Beckman DxI-specific reference interval using an indirect Hoffman approach applied to 61,117 routine clinical samples.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_cclm-2026-0658_abs_003\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Diagnostic thresholds for total B12 varied widely across the UK (65\u2013239\u202fng\/L; 48\u2013176\u202fpmol\/L). Only 16.6\u202f% of laboratories used the NG239\u00a0best-practice threshold of 180\u202fng\/L (133\u202fpmol\/L). The Beckman DxI total B12 assay was not compatible with the NG239\u00a0cut-off; a lower threshold, such as a locally derived cut-off or the manufacturer\u2019s recommended 145\u202fng\/L (107\u202fpmol\/L), was indicated for this platform.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_cclm-2026-0658_abs_004\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Substantial national heterogeneity in applied total B12 diagnostic thresholds persist, with limited adoption of NG239 guidance. Platform-related analytical bias undermines the use of universal decision limits. For Beckman DxI, use of a platform-appropriate threshold is required to support clinically consistent diagnosis of vitamin B12 deficiency.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1515\/cclm-2026-0658","type":"journal-article","created":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T09:40:09Z","timestamp":1782207609000},"page":"2389-2397","source":"Crossref","is-referenced-by-count":1,"title":["Unwarranted variation in total B12 test thresholds for the diagnosis of vitamin B12 deficiency across the UK and the validation of a method-specific total B12 reference interval for the Beckman Coulter DxI platform to support implementation of NICE NG239"],"prefix":"10.1515","volume":"64","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9509-8826","authenticated-orcid":false,"given":"Emma","family":"Stevenson","sequence":"first","affiliation":[{"name":"Clinical Biochemistry, Pathology , Gloucestershire Royal Hospital , Gloucester , UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1045-8456","authenticated-orcid":false,"given":"Rachel","family":"Marrington","sequence":"additional","affiliation":[{"name":"Birmingham Quality , University Hospitals Birmingham NHS Foundation Trust , Birmingham , UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Duncan","family":"Stevenson","sequence":"additional","affiliation":[{"name":"Department of Communications and Engagement , Cheltenham General Hospital , Cheltenham , UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thomas","family":"Morris","sequence":"additional","affiliation":[{"name":"The Nutristasis Unit , Synnovis, St Thomas\u2019 Hospital , London , UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6482-4373","authenticated-orcid":false,"given":"Finlay","family":"MacKenzie","sequence":"additional","affiliation":[{"name":"Birmingham Quality , University Hospitals Birmingham NHS Foundation Trust , Birmingham , UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4786-9240","authenticated-orcid":false,"given":"Dominic J.","family":"Harrington","sequence":"additional","affiliation":[{"name":"The Nutristasis Unit , Synnovis, St Thomas\u2019 Hospital , London , UK"},{"name":"School of Biosciences and Medicine , University of Surrey , Guildford , UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"374","published-online":{"date-parts":[[2026,6,24]]},"reference":[{"key":"2026092809015496269_j_cclm-2026-0658_ref_001","doi-asserted-by":"crossref","unstructured":"Green, R. 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