[Factitious hyperthyroidism due to intake of herbal supplements for weight reduction]

Factitious thyrotoxicosis is characterized by the intentional or accidental intake of excess thyroid hormones or their derivatives. We describe 6 cases of patients who developed thyrotoxicosis and adverse effects by weight-reducing herbal medicines. Currently there is a lot of publicity about supplements that "help to lose weight", which are over-the-counter and widely distributed in health food stores or online, which is why it is common to have patients who consume them, without many noticing their possible risks. If factitious hyperthyroidism is suspected, we should request thyroglobulin and anti-thyroglobulin tests, as well as a thyroid scan or uptake curve. To make the differential diagnosis between intake of thyroxine (T4) or triiodothyronine (T3) or its derivatives, we must request the measurement of T4 and T3. In case of ingestion of T4, T4 and T3 will be elevated, but in case of ingestion of triodothyronine or its derivatives, T4 will be decreased with elevated T3.