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Title
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Misdiagnosis of Graves' hyperthyroidism due to therapeutic biotin intervention
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Author
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Abstract
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| Background: Lately, high dose of biotin is often given orally to patients with a primary progressive multiple sclerosis (PPMS). However, the molecule biotin is also a principle compound in various analytic immunoassays. Clinical case: An asymptomatic 60-year-old woman with PPMS on high dose of biotin therapy (3 x 100mg/d) displayed abnormal thyroid function tests (TSH 0.02mU/l, fT4>103pmol/l, and fT3>46pmol/l). TSH was determined by a homogeneous sandwich chemiluminescent immunoassay and fT4 and fT3 were both determined by a homogeneous, sequential, chemiluminescent immunoassay. TSH receptor antibodies were found to be markedly elevated (>40IU/l) using a electrochemiluminescence immunoassay, suggestive for Graves' hyperthyroidism. Due to inconsistency between clinical presentation and laboratory results, thyroid function tests have been repeated with two other immunoassays. A direct, labeled antibody, competitive immunoassay to determine TSH and a luminescent immunometric immunoassay to determine fT4 and fT3 showed a subclinical hyperthyroidism (TSH<0.02mU/l, fT4 15.9pmol/l, and fT3 4.7pmol/l). Normal thyroid function tests (TSH 1.66mU/l, fT4 15.3pmol/l, and fT3 4.7pmol/l) were obtained by a chemiluminescent microparticle immunoassay. All abnormal levels of TSH, fT4, fT3, and TSH-R-Ab were observed in immunoassays using biotin as a reagent. Conclusion: Abnormal thyroid function tests in this euthyroid patient were found to be false due to significant interference of supraphysiological levels of plasma biotin. Laboratory tests applying immunoassays using a biotin-containing reagent should be interpreted with caution in patients on biotin substitution. |
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Language
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English
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Source (journal)
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Acta clinica Belgica / Belgian Society of Internal Medicine [Ghent]; Royal Belgian Society of Laboratory Medicine. - Gent, 1997, currens
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Publication
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Gent
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2018
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ISSN
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1784-3286
[print]
2295-3337
[online]
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Volume/pages
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73
:5
(2018)
, p. 372-376
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ISI
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000443836600010
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Pubmed ID
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29098964
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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