{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T06:35:00Z","timestamp":1778567700688,"version":"3.51.4"},"reference-count":14,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2017,9,4]],"date-time":"2017-09-04T00:00:00Z","timestamp":1504483200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2017,9,4]],"date-time":"2017-09-04T00:00:00Z","timestamp":1504483200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"},{"start":{"date-parts":[[2017,9,4]],"date-time":"2017-09-04T00:00:00Z","timestamp":1504483200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100001316","name":"Abbott Laboratories","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100001316","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100001316","name":"Abbott Laboratories","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100001316","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["wiley.com"],"crossmark-restriction":true},"short-container-title":["Int J Lab Hematology"],"published-print":{"date-parts":[[2018,2]]},"abstract":"Abstract<\/jats:title>Introduction<\/jats:title>Total vitamin B12 levels decrease significantly during pregnancy and recover to normal values within 8\u2010week postpartum. Holotranscobalamin (holoTC<\/jats:styled-content>) reflects the active part of vitamin B12 and has been shown to remain constant during pregnancy and postpartum. A mechanism of redistribution of vitamin B12 is suggested, with a shift toward holoTC<\/jats:styled-content> if there is insufficient total vitamin B12 available. Our objective was to examine vitamin B12 deficiency and the active vitamin B12 fraction in postpartum women.<\/jats:p><\/jats:sec>Methods<\/jats:title>Total vitamin B12 and holoTC<\/jats:styled-content> were measured in 171 women within 48\u00a0hours (T0) and at 5\u00a0weeks (T5) postpartum. Vitamin B12 deficiency was defined as total vitamin B12\u00a0<\u00a0180\u00a0pmol\/L or holoTC<\/jats:styled-content> <32\u00a0pmol\/L. The active vitamin B12 fraction was defined as holoTC<\/jats:styled-content>\/total vitamin B12.<\/jats:p><\/jats:sec>Results<\/jats:title>Without intervention, vitamin B12 deficiency based on both serum total vitamin B12 and holoTC<\/jats:styled-content> changed from 75% and 60%, to respectively 10% and 6% at T5. The fraction of active vitamin B12 was significant higher in vitamin B12 deficient women at both time points and across time (P<\/jats:italic>\u00a0<\u00a0.0001 and P<\/jats:italic>\u00a0=\u00a0.002). A high fraction of active vitamin B12 was only present in women with total vitamin B12 deficiency at T0. At T5, no high vitamin B12 fraction was found.<\/jats:p><\/jats:sec>Conclusion<\/jats:title>The changes in total vitamin B12 levels seem to be based on a physiological changes rather than vitamin B12 deficiency. The results of this study confirm the hypothesis that a shift toward the metabolic active vitamin B12 (holoTC<\/jats:styled-content>) occurs in women with insufficient available total vitamin B12.<\/jats:p><\/jats:sec>","DOI":"10.1111\/ijlh.12730","type":"journal-article","created":{"date-parts":[[2017,9,4]],"date-time":"2017-09-04T08:26:42Z","timestamp":1504513602000},"page":"72-76","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["The distribution of total vitamin B12, holotranscobalamin, and the active vitamin B12 fraction in the first 5\u00a0weeks postpartum"],"prefix":"10.1111","volume":"40","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2126-3411","authenticated-orcid":false,"given":"D. A. A.","family":"van der Woude","sequence":"first","affiliation":[{"name":"CoRPS Department of Medical and Clinical Psychology Tilburg University Tilburg the\u00a0Netherlands"},{"name":"Department of Gynecology and Obstetrics Elisabeth\u2010TweeSteden Hospital Tilburg the\u00a0Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J. M. A.","family":"Pijnenborg","sequence":"additional","affiliation":[{"name":"Department of Gynecology and Obstetrics Radboud University Medical Center Nijmegen the Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J.","family":"de Vries","sequence":"additional","affiliation":[{"name":"CoRPS Department of Medical and Clinical Psychology Tilburg University Tilburg the\u00a0Netherlands"},{"name":"Department of Medical Psychology Elisabeth\u2010TweeSteden Hospital Tilburg the\u00a0Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"E. M.","family":"van Wijk","sequence":"additional","affiliation":[{"name":"Laboratory of Clinical Chemistry and Hematology Elisabeth\u2010TweeSteden Hospital Tilburg the Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2017,9,4]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1079\/BJN2000209"},{"key":"e_1_2_9_3_1","doi-asserted-by":"crossref","first-page":"928","DOI":"10.1093\/clinchem\/48.6.928","article-title":"Longitudinal concentrations of vitamin B(12) and vitamin B(12)\u2010binding proteins during uncomplicated pregnancy","volume":"48","author":"Koebnick C","year":"2002","journal-title":"Clin Chem"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.0902-4441.2006.t01-1-EJH2550.x"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1093\/jn\/137.8.1863"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.3324\/haematol.11636"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1515\/CCLM.2007.343"},{"key":"e_1_2_9_8_1","first-page":"2789","article-title":"Diagnosis of vitamin B12 deficiency revised [article in Dutch]","volume":"149","author":"Wiersinga WJ","year":"2005","journal-title":"Nederlands Tijdschrift van Geneeskunde"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.semcdb.2011.05.005"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/ajh.2830480409"},{"key":"e_1_2_9_11_1","first-page":"297","volume-title":"Nordic Nutrition Recommendations. 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