Patients present with hyperthyroidism and may be mistaken for Graves’ disease, if TSH receptor positive, or thyroiditis because of absent uptake on a thyroid radionuclide uptake scan due to suppression of thyroid function by exogenous thyroid hormones.[8] Ingestion of thyroid hormone also suppresses thyroglobulin levels helping to differentiate thyrotoxicosis factitia from other causes of hyperthyroidism, in which serum thyroglobulin is elevated. Caution, however, should be exercised in interpreting thyroglobulin results without thyroglobulin antibodies, since thyroglobulin antibodies commonly interfere in thyroglobulin immunoassays causing false positive and negative results which may lead to clinical misdirection. In such cases, increased fecal thyroxine levels in thyrotoxicosis factitia may help differentiate it from other causes of hyperthyroidism.[citation needed]
^Mathioudakis N., Cooper D.S. (2015) Exogenous Thyrotoxicosis. In: Davies T. (eds) A Case-Based Guide to Clinical Endocrinology. Springer, New York, NY
^Lucie Wartique, Lucie Pothen, Nathalie Pirson, Michel P. Hermans, Michel Lambert & Halil Yildiz (2017) An unusual cause of epidemic thyrotoxicosis. In: Acta Clinica Belgica, 72:6, 451–453, DOI: 10.1080/17843286.2017.1309336