Factitious hyperthyroidism is higher-than-normal thyroid hormone levels in the blood that occur from taking too much thyroid hormone medicine.
Factitious thyrotoxicosis; Thyrotoxicosis factitia; Thyrotoxicosis medicamentosa
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.
Hyperthyroidism can also be caused by taking too much thyroid hormone medicine for hypothyroidism. This is called factitious hyperthyroidism. When this occurs because the prescribed dosage of hormone medicine is too high, it is called iatrogenic, or doctor-induced, hyperthyroidism.
Factitious hyperthyroidism can also occur when someone takes too much thyroid hormone on purpose. These may be people:
- Who have mental disorders such as Munchausen syndrome
- Who are trying to lose weight
- Who want to get money from the insurance company
Children may take thyroid hormone pills accidentally.
In rare cases, factitious hyperthyroidism is caused by eating meat that has thyroid gland tissue in it.
The symptoms of factitious hyperthyroidism are the same as those of hyperthyroidism caused by a thyroid gland disorder, except that:
- There is no goiter. The thyroid gland is often small.
- The eyes do not bulge, as they do in Graves disease (the most common type of hyperthyroidism).
- The skin over the shins does not thicken, as it sometimes does in people who have Graves disease.
Exams and Tests
Blood tests used to diagnose factitious hyperthyroidism include:
Your health care provider will tell you to stop taking thyroid hormone. If you need to take it, your provider will reduce the dosage.
You should be re-checked in 2 to 4 weeks to be sure that the signs and symptoms are gone. This also helps to confirm the diagnosis.
People with Munchausen syndrome will need mental health treatment and follow-up.
Factitious hyperthyroidism will clear up on its own when you stop taking or lower the dosage of thyroid hormone.
When factitious hyperthyroidism lasts a long time, the same complications as untreated or improperly treated hyperthyroidism may develop:
- Abnormal heartbeat (atrial fibrillation)
- Chest pain (angina)
- Heart attack
- Loss of bone mass (if severe, osteoporosis)
- Weight loss
When to Contact a Medical Professional
Contact your provider if you have symptoms of hyperthyroidism.
Thyroid hormone should be taken only by prescription and under the supervision of a provider.
Davies TF, Laurberg P, Bahn RS. Hyperthyroid disorders. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 12.
Kopp P. Autonomously functioning thyroid nodules and other causes of thyrotoxicosis. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 85.