{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T18:03:31Z","timestamp":1786730611775,"version":"build-2736575974"},"reference-count":26,"publisher":"Croatian Society for Medical Biochemistry and Laboratory Medicine","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biochem. med. (Online)"],"published-print":{"date-parts":[[2021,2,15]]},"abstract":"<jats:p>We describe a case of severe hypervitaminosis D and mild hypercalcaemia in a 68-year-old woman who presented with fatigue and weight loss. Her 25-hydroxy vitamin D (25OHD) was &gt; 400 nmol\/L (50-150) and corrected serum calcium was 2.83 mmol\/L (2.1-2.6). Her intact parathyroid hormone (PTH) was 4.9 pmol\/L (2.0-9.5). Further investigation revealed an IgM kappa paraprotein, and a bone marrow aspirate confirmed a diagnosis of lymphoplasmacytic lymphoma\/Waldenstrom\u2019s macroglobulinemia (LPL\/WM). As the vitamin D level was discordant with the patient\u2019s other results and presentation, the presence of an assay interferent was suspected. A 1-in-2 dilution of the sample returned a 25OHD result of 84 nmol\/L in keeping with the presence of an interferent. Testing for rheumatoid factor was negative. The sample was treated with an antibody blocking reagent (Scantibodies) and results were not consistent with heterophile antibody interference. The sample was then analysed using liquid chromatography tandem mass spectrometry (LC-MS\/MS), which returned a 25OHD result of 82 nmol\/L. Testing on an alternative immunoassay platform produced a 25OHD result of 75 nmol\/L. Reapeted testing on the original platform following reduction of the monoclonal paraprotein with chemotherapy, returned a result of 64 nmol\/L. The patient\u2019s mild hypercalcaemia persisted following resolution of the monoclonal paraprotein, in keeping with a diagnosis of primary hyperparathyroidism. This case highlights the potential for paraproteins to cause assay interference, and the importance of considering interference when results are incongruous with the clinical presentation.<\/jats:p>","DOI":"10.11613\/bm.2021.011001","type":"journal-article","created":{"date-parts":[[2020,12,18]],"date-time":"2020-12-18T21:09:13Z","timestamp":1608325753000},"page":"149-155","source":"Crossref","is-referenced-by-count":7,"title":["Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia"],"prefix":"10.11613","volume":"31","author":[{"given":"Emma","family":"Whittle","sequence":"first","affiliation":[{"name":"Department of Endocrinology and Diabetes, Mater Hospital, South Brisbane QLD, Australia; Faculty of Medicine, University of Queensland, Brisbane QLD, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elzahn","family":"de Waal","sequence":"additional","affiliation":[{"name":"Department of Chemical Pathology, Mater Pathology, South Brisbane QLD, Australia; Faculty of Medicine, University of Queensland, Brisbane QLD, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tony","family":"Huynh","sequence":"additional","affiliation":[{"name":"Department of Chemical Pathology, Mater Pathology, South Brisbane QLD, Australia; Department of Endocrinology and Diabetes, Queensland Children\u2019s Hospital, South Brisbane QLD, Australia; Faculty of Medicine, University of Queensland, Brisbane QLD, Austral"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oliver","family":"Treacy","sequence":"additional","affiliation":[{"name":"Department of Chemical Pathology, Mater Pathology, South Brisbane QLD, Australia; Faculty of Medicine, University of Queensland, Brisbane QLD, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adam","family":"Morton","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Diabetes, Mater Hospital, South Brisbane QLD, Australia; Faculty of Medicine, University of Queensland, Brisbane QLD, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4885","published-online":{"date-parts":[[2021,2,16]]},"reference":[{"key":"key20201218160854_r1","first-page":"118","article-title":"\u201cExcess gooD can be Dangerous\u201d. 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