The intentional and surreptitious ingestion of thyroid hormone to feign the diagnosis of hyperthyroidism is factitious thyrotoxicosis. A form of Munchausen’s syndrome, this psychiatric disorder is motivated by the patient’s desire to assume the sick role for emotional gain [2]. This is most commonly observed in young or middle-aged women with a history of childhood emotional deprivation and/or current sexual or relationship problems; in some cases, the patient may carry a diagnosis of borderline personality disorder or post-traumatic stress disorder [3]. Other suggestive historical features may include a connection to the healthcare profession, lack of appropriate concern for health problems, or a past history of feigning illness [2]. On the other hand, thyroid hormone abuse may also be observed in individuals without an underlying psychiatric disorder, usually for the purpose of weight loss [4]. In these cases, the patient’s motivation is not to feign a medical condition, but rather to derive perceived benefits of hyperthyroidism (weight loss, increased energy, etc.) [4].

As challenging as it may be to diagnose factitious thyrotoxicosis, it can be even more difficult to identify cases of inadvertent thyrotoxicosis. In some cases, the problem may be as simple as a pharmacy or patient medication error. For patients already prescribed thyroid hormone, it may be helpful to verify that they are taking the prescribed dose by having them bring in their medications for review and/or contacting their pharmacy. One unusual cause of medication error is inadvertent ingestion of a pet’s thyroxine dose in place of prescribed thyroxine [5]. Accidental thyroxine poisoning has occurred in young children with access to the medication [6, 7]. Rarely, outbreaks of thyrotoxicosis have occurred following consumption of ground beef contaminated with bovine thyroid gland (so-called hamburger thyrotoxicosis) [8].

In recent years, there have been increasing reports of accidental overdose of thyroid hormone caused by weight-reducing herbal medications containing thyroid hormone as a hidden ingredient [9, 10]. The use of herbal or natural supplements is widespread in the USA and these products are not regulated by the FDA. Surprisingly, as many as 7 % of such supplements contain undisclosed substances [9]. It has been estimated that half of patients do not disclose their use of supplements to physicians [9]. Some easily accessible nonprescription supplements taken for the purposes weight loss, energy, or “thyroid support” have been found to contain clinically significant amounts of T3 and T4 [9–11]. Therefore, the use such supplements poses a serious risk of hyperthyroidism-related cardiovascular complications. In some instances, supplements adulterated with thyroid hormone may have a beta-blocker added to mask hyperadrenergic symptoms, which could make recognition of the thyrotoxic patient even more difficult [9]. In patients with underlying thyroid disease, exogenous thyrotoxicosis can complicate the clinical picture and lead to a delay in diagnosis [10].