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Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia

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 > 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...

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Autores principales: Whittle, Emma, de Waal, Elzahn, Huynh, Tony, Treacy, Oliver, Morton, Adam
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Croatian Society of Medical Biochemistry and Laboratory Medicine 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7745154/
https://www.ncbi.nlm.nih.gov/pubmed/33380896
http://dx.doi.org/10.11613/BM.2021.011001
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author Whittle, Emma
de Waal, Elzahn
Huynh, Tony
Treacy, Oliver
Morton, Adam
author_facet Whittle, Emma
de Waal, Elzahn
Huynh, Tony
Treacy, Oliver
Morton, Adam
author_sort Whittle, Emma
collection PubMed
description 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 > 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’s macroglobulinemia (LPL/WM). As the vitamin D level was discordant with the patient’s 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’s 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.
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spelling pubmed-77451542020-12-29 Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia Whittle, Emma de Waal, Elzahn Huynh, Tony Treacy, Oliver Morton, Adam Biochem Med (Zagreb) Preanalytical Mysteries 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 > 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’s macroglobulinemia (LPL/WM). As the vitamin D level was discordant with the patient’s 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’s 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. Croatian Society of Medical Biochemistry and Laboratory Medicine 2020-12-15 2021-02-15 /pmc/articles/PMC7745154/ /pubmed/33380896 http://dx.doi.org/10.11613/BM.2021.011001 Text en Croatian Society of Medical Biochemistry and Laboratory Medicine. https://creativecommons.org/licenses/by/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) ) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Preanalytical Mysteries
Whittle, Emma
de Waal, Elzahn
Huynh, Tony
Treacy, Oliver
Morton, Adam
Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia
title Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia
title_full Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia
title_fullStr Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia
title_full_unstemmed Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia
title_short Pre-analytical mysteries: A case of severe hypervitaminosis D and mild hypercalcaemia
title_sort pre-analytical mysteries: a case of severe hypervitaminosis d and mild hypercalcaemia
topic Preanalytical Mysteries
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7745154/
https://www.ncbi.nlm.nih.gov/pubmed/33380896
http://dx.doi.org/10.11613/BM.2021.011001
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