Background: Exogenous hyperthyroidism is a rare cause of thyrotoxicosis. It is caused by ingestion of excessive amounts of thyroid hormone, which could be intentional or surreptitious (known as factitious thyrotoxicosis). One of the most exceptional cause is the intake of meat or sausage containing thyroid tissue, inadvertently mixed with traces of muscles and other tissues of the animals neck (hamburger thyrotoxicosis). The clinical symptoms are indistinguishable from other common causes of hyperthyroidism as Graves disease.
Case report: A 82 years-old woman with recurrent self-limiting hyperthyroidism for three years who was admitted in our Endocrinology department. She had weight loss up to 3 kg and abnormal heart beats sensation. The physical examination was irrelevant. The biochemical test showed not detectable stimulating thyroid, thyroglobulin and peroxidases antibodies. The thyroid scintigraphy with Tc99m pertechnetate displayed a heterogeneous uptake pattern and a small normal thyroid. The thyroglobulin levels were low. A further interview with the patient reported a daily consumption of pork sausage. When she stopped consumption of these sausages, she became asymptomatic and thyroid function was normalized. The pathology analysis of a sausage sample detected tissues from the porks neck, such as thymus, cartilage and salivary glands, but not traces of thyroid glandule.
Conclusions: Thyrotoxicosis induced by food should be suspected in cases of self-limiting and recurrent episodes of hyperthyroidism with suppressed thyroid stimulating hormone (TSH), high levels of triiodothyronine (FT), low levels of thyroglobulin and not detectable thyroid antibodies. The scintigraphy shows usually a low uptake pattern. The levels of FT3 and thyroxine (FT4) could be useful to differentiate the kind of hormone intake. This case illustrates the importance of a thorough and detailed anamnesis to get a accurate differential diagnosis of a repeat silent thyroiditis.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.
05 - 09 May 2012
European Society of Endocrinology