{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T07:38:13Z","timestamp":1791617893112,"version":"4.3.4"},"reference-count":4,"publisher":"SMC Media","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>Introduction:\u00a0High blood concentrations of vitamin B12 are often caused by over-supplementation. However, there are instances in which augmented vitamin B12 levels are seen in the absence of supplements. Macro-vitamin B12 is an underrated cause of supra-physiological cobalamin plasma levels. Case description:\u00a0A 70-year-old man was referred to an ambulatory internal medicine centre because of high vitamin B12 levels yet he denied taking supplements. An X-ray showed a tumour in the right upper lobe of the lung, which triggered further examinations. An MRI scan of the brain came back normal as well as a CT scan of the abdomen, and colonoscopy. The pulmonologist requested a PET-CT scan, which showed an isolated 18-FDG uptake in the area of the lung mass that was detected earlier. The patient underwent surgery with adjuvant cis-platinum and gemcitabine and is still making good progress. The vitamin B12 levels persisted after successful treatment of lung adenocarcinoma; determination of vitamin B12 after PEG (polyethylene glycol) precipitation showed normal concentrations. Discussion:\u00a0A high vitamin B12 plasma concentration in the absence of vitamin supplementation can be a daunting diagnostic problem for the internist, as there are several possible underlying causes. In this case the diagnosis of lung carcinoma was made, the patient was treated appropriately, yet this pathology had no correlation with the cobalamin levels. Conclusion:\u00a0A high vitamin B12 concentration can be the impetus of thorough medical inquiries. Internists should be careful not to forget macro-vitamin B12 as a possible source of falsely elevated vitamin B12 values.<\/jats:p>","DOI":"10.12890\/2023_004188","type":"journal-article","created":{"date-parts":[[2023,11,30]],"date-time":"2023-11-30T05:16:51Z","timestamp":1701321411000},"source":"Crossref","is-referenced-by-count":1,"title":["Macro-vitamin B12 as cause of falsely elevated cobalamin levels"],"prefix":"10.12890","volume":"11","author":[{"given":"Jamal","family":"Belkhouribchia","sequence":"first","affiliation":[{"name":"Hasselt University, Agoralaan, Hasselt, Belgium; Endocrinology Center, Hasselt, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"10397","published-online":{"date-parts":[[2023,11,29]]},"reference":[{"key":"10.12890\/2023_004188_ref1","doi-asserted-by":"crossref","unstructured":"<li>Andr\u00e8s E, Serraj K, Zhu J, Vermorken AJM. The pathophysiology of elevated vitamin B12 in clinical practice. <em>QJM<\/em> 2013;<strong>106<\/strong>:505\u2013515.<\/li>","DOI":"10.1093\/qjmed\/hct051"},{"key":"10.12890\/2023_004188_ref2","doi-asserted-by":"crossref","unstructured":"<li>Shipton MJ, Thachil J. Vitamin B12 deficiency \u2013 a 21st century perspective. <em>Clin Med (Lond)<\/em> 2015;<strong>15<\/strong>:145\u2013150.<\/li>","DOI":"10.7861\/clinmedicine.15-2-145"},{"key":"10.12890\/2023_004188_ref3","doi-asserted-by":"crossref","unstructured":"<li>Jeffery J, Millar H, Mackenzie P, Fahie-Wilson M, Hamilton M, Ayling RM. An IgG complexed form of vitamin B12 is a common cause of elevated serum concentrations. <em>Clin Biochem<\/em> 2010;<strong>43<\/strong>:82\u201388.<\/li>","DOI":"10.1016\/j.clinbiochem.2009.08.022"},{"key":"10.12890\/2023_004188_ref4","doi-asserted-by":"crossref","unstructured":"<li>Soleimani R, Favresse J, Roy T, Gruson D, Fill\u00e9e C. Macro vitamin B12: an underestimated threat. <em>Clin Chem Lab Med<\/em> 2020;<strong>58<\/strong>:408\u2013415. <\/li>","DOI":"10.1515\/cclm-2019-0999"}],"container-title":["European Journal of Case Reports in Internal Medicine"],"original-title":[],"link":[{"URL":"https:\/\/www.ejcrim.com\/index.php\/EJCRIM\/article\/download\/4188\/3744","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.ejcrim.com\/index.php\/EJCRIM\/article\/download\/4188\/3745","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.ejcrim.com\/index.php\/EJCRIM\/article\/download\/4188\/3745","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,8,19]],"date-time":"2025-08-19T15:20:48Z","timestamp":1755616848000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ejcrim.com\/index.php\/EJCRIM\/article\/view\/4188"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,11,29]]},"references-count":4,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2024]]}},"URL":"https:\/\/doi.org\/10.12890\/2023_004188","relation":{"has-manifestation":[{"id-type":"other","id":"1-108-4188-g3744","asserted-by":"subject"},{"id-type":"other","id":"1-108-4188-g3745","asserted-by":"subject"}],"is-part-of":[{"id-type":"other","id":"1-108","asserted-by":"subject"}]},"ISSN":["2284-2594"],"issn-type":[{"value":"2284-2594","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,11,29]]}}}