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Factitious thyrotoxicosis: how to find it

Pakaworn Vorasart / Chutintorn Sriphrapradang
  • Corresponding author
  • Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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Published Online: 2019-03-30 | DOI: https://doi.org/10.1515/dx-2019-0015



Although the most common cause of thyrotoxicosis is Graves’ disease, the determination of the cause of thyrotoxicosis is important for establishing appropriate management. Diagnosis of surreptitious ingestion of thyroid hormones or factitious thyrotoxicosis often presents a difficult challenge especially in a patient with previously diagnosed Graves’ disease. The objective of this report was to demonstrate various approaches to support the diagnosis of factitious thyrotoxicosis.

Case presentation

We describe a patient with underlying Graves’ disease who underwent definitive therapy and needed long-term levothyroxine (LT4) replacement therapy. Later she developed thyrotoxicosis. Although factitious thyrotoxicosis was suspected because of very low thyroid uptake and low thyroglobulin (Tg) levels with the absence of thyroglobulin antibodies (TgAbs), she still refused any medication or substance use. After the administration of bile acid sequestrant, the thyroid hormone levels rapidly returned to normal within 1 month.


The diagnosis of factitious thyrotoxicosis is based upon the absence of goiter, suppressed serum Tg level, decreased radioactive iodine (RAI) uptake, and excellent response after cholestyramine treatment.

Keywords: factitious disorders; Graves’ disease; thyroxine


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About the article

Corresponding author: Chutintorn Sriphrapradang, MD, Assistant Professor of Medicine, Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, 270 Rama 6 Road, Bangkok 10400, Thailand, Phone/Fax: +66 2 201 1647

Received: 2019-02-24

Accepted: 2019-03-15

Published Online: 2019-03-30

Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved the submission.

Research funding: None declared.

Employment or leadership: None declared.

Honorarium: None declared.

Competing interests: None declared.

Citation Information: Diagnosis, 20190015, ISSN (Online) 2194-802X, ISSN (Print) 2194-8011, DOI: https://doi.org/10.1515/dx-2019-0015.

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