Definition of Factitious hyperthyroidism:

Factitious hyperthyroidism is the presence of excessive thyroid hormone levels, caused by taking too much thyroid hormone medication.

Causes, incidence, and risk factors:

The thyroid gland produces the hormones thyroxine (T4) and triiodothyronine (T3). In most cases of hyperthyroidism, the thyroid gland itself produces too much of these hormones.

However, hyperthyroidism can also be caused by taking too much thyroid hormone medication for hypothyroidism. This is called factitious hyperthyroidism. When this occurs because the prescribed dose of hormone medication is too high, it is called iatrogenic, or "doctor-induced," hyperthyroidism.

Factitious hyperthyroidism can also occur when a patient intentionally takes too much thyroid hormone. People with psychiatric disorders such as Munchausen syndrome, people attempting to lose weight and those seeking fraudulent insurance compensation sometimes misuse thyroid hormone. Children occasionally ingest thyroid hormone pills accidentally.

In rare cases, factitious hyperthyroidism has been found to be caused by eating meat contaminated with thyroid gland tissue.