The thyroid regulates certain body functions, such as temperature control and metabolism. The thyroid produces two hormones, T3 and T4, which are produced in response to release of thyroid stimulating hormone, or TSH, from the pituitary. People with an underactive thyroid, called hypothyroid, often take thyroid medication to return levels to normal. Taking too much thyroid medication causes factitious hyperthyroidism, also called thyrotoxicosis factitia, an increase in thyroid levels that can have serious side effects.
Causes
Factitious hyperthyroidism can occur when medical personnel prescribe too high a dose of thyroid medication. Sometimes people take too much thyroid medication by accident; this occurs more often in the elderly or people with mental disabilities. Children can also take an accidental overdose of thyroid medication prescribed for another family member. Some people, however, take an overdose of thyroid medication deliberately. These people may have Munchhausen's syndrome, a mental disorder where people inflict harm upon themselves to gain attention.
Types
Factitious hyperthyroidism speeds up the metabolism, causing symptoms similar to hyperthyroidism. Common side effects include nervousness, irritability, increased appetite, weight loss, palpitations, increased sweating and insomnia. Frequent bowel movements, hyperactivity, weakness and increased sensitivity to heat also occur commonly.
Diagnosis
Blood work helps determine whether side effects are caused by factitious hyperthyroidism or other types of hyperthyroidism. Blood work in people with factitious hyperthyroidism will show high levels of T3 and T4 and low levels of TSH and thyroglobulin. Thyroglobulin levels are elevated in all other types of hyperthyroidism, the Merck Manuals Online Medical Library reports. A radioactive iodine uptake test will also be low, as opposed to the high level normally seen in people with overactive thyroid, Merck adds. People with factitious hyperthyroidism do not have the eye effects common to Graves's disease, the most common type of hyperthyroidism, MedlinePlus states. The thyroid gland is small, and no goiter is felt.
Complications
Side effects of factitious hyperthyroidism can cause serious complications. Heart problems such as atrial fibrillation, a rapid quivering of the atria, the top chambers of the heart and congestive heart failure can occur. Osteoporosis, a decrease in bone density that increases the risk of fractures, can also occur. Thyrotoxic crisis, a sudden worsening of symptoms including rapid pulse, fever, marked weakness and delirium, can lead to death without prompt medical treatment, Merck warns.
Treatment
Stopping the excess medication treats the side effects and cures factitious hyperthyroidism. If thyroid medication is medically necessary, the dose is reduced. If the overdose occurred deliberately, psychiatric follow-up to treat the underlying disease is necessary to prevent the person from doing harm to themselves again.
