Before you begin reading about hyperthyroidism, please read a description of the thyroid gland for a basic understanding of its structure and function.
Hyperthyroidism (overactive thyroid) is a condition in which the thyroid gland makes too much thyroid hormone. The over-secretion of thyroid hormone leads to over-activity of the body's metabolism, causing sudden weight loss, a rapid or irregular heartbeat, sweating and nervousness or irritability.
Hyperthyroidism is a relatively rare condition in children. The vast majority of hyperthyroidism cases are caused by Graves’ disease (autoimmune hyperthyroidism). Hyperthyroidism can also be caused by an autonomous nodule (a nodule functioning on its own) or by a non-immune inflammation, such as a viral bacterial infection.
Graves’ disease occurs when the child’s immune system develops antibodies that attach to the thyroid cells, causing them to produce more thyroid hormone. The antibodies (TSH receptor antibodies; TRAb) bind to the thyroid-stimulating hormone (TSH) receptor and may cause stimulation or, less commonly, blocking of thyroid hormone production.
Graves’ disease is much less common than autoimmune hypothyroidism (Hashimoto’s thyroiditis). It is more common in girls than in boys, and more common in adolescents. Graves' disease was named after an Irish doctor, Sir Robert Graves, who first described the condition in the early 19th century. Autoimmune diseases occur more frequently within a family of an affected person, but it is difficult to predict if an individual family member will develop an autoimmune disease and what specific disease he/she may develop.
There is a very rare, but severe and life-threatening, form of hyperthyroidism called thyroid storm. This is a condition in which there are extremely high levels of thyroid hormone that can cause high fever, dehydration, diarrhea, rapid and irregular heart rate, shock and death, if not treated. Patients with thyroid storm are cared for in the intensive care unit with intravenous fluids, steroids, cold-iodine, beta-blockers and/or anti-thyroid medications.
The signs and symptoms of hyperthyroidism may be mild or severe, at times without relationship to the level of thyroid hormone. Some patients may have significant complaints with slightly elevated thyroid hormone levels, and some patients with significantly elevated thyroid hormone levels may have fewer symptoms than would be expected.
The following are the most common signs of hyperthyroidism. Each individual may experience a different number and severity of signs.
Symptoms of hyperthyroidism may include:
In addition to the signs and symptoms of Graves' disease, the diagnosis of hyperthyroidism is confirmed by blood tests and, on occasion, by thyroid ultrasound or nuclear medicine uptake and scan. A thyroid uptake and scan helps determine how well the thyroid tissues absorb iodine.
Hyperthyroidism is diagnosed when the thyroid stimulating hormone (TSH) level is below normal and the triiodothyronine (T3) and thyroxine (T4) (total T4 or free-T4) levels are above normal. In "early" Graves’ disease the T3 may be elevated before the T4. The presence of thyroid receptor antibodies (TRAb, TSI and/or TBII) help to confirm the diagnosis.
Imaging studies may be used to more completely define the hyperthyroidism.
In general, patients with hyperthyroidism will be evaluated and cared for in the Division of Endocrinology and Diabetes and referred to the Pediatric Thyroid Center if needed.
Depending on the cause of hyperthyroidism, treatment may include:
Most children and adolescents will be started on anti-thyroid medication at the time of diagnosis. For patients with severe symptoms, including elevated heart rate, palpitations and anxiousness, a medicine called a "beta-blocker" will be added to help decrease symptoms while the anti-thyroid medications take effect.
Up to 50 percent of patients treated with medications may eventually achieve remission, defined as resolution of Graves' disease for at least 18 months after stopping medication. Unfortunately, in those who appear to have their Graves’ disease resolve, 30 to 40 percent may experience a relapse. The younger the patient, the higher the thyroid hormone levels are at the time of diagnosis and the more difficult it is to control the hyperthyroidism, the less likely it is for the patient to achieve remission.
Patients who do not tolerate the anti-thyroid medication, whose disease is difficult to control with usual medical therapy, or those who have not achieved remission despite prolonged medical therapy, are referred to the Pediatric Thyroid Center at CHOP for evaluation.
Two options are available to permanently treat hyperthyroidism: radioactive iodine (RAI) ablation (medically destroying the thyroid gland) or thyroidectomy (surgically removing the thyroid). These options are referred to as “definitive therapy.” Prior to definitive therapy, we may order a thyroid ultrasound. If a thyroid nodule is found, further evaluation with fine-needle aspiration biopsy (FNA) will be recommended. In addition, for patients with Graves’ disease and thyroid nodules, surgery to remove the thyroid instead of RAI ablation may be recommended.
The Pediatric Thyroid Center at CHOP will work with you and your child to come up with the best treatment plan for your child's specific illness.
With definitive therapy, patients will need to take thyroid hormone replacement for the rest of their lives. Thyroid hormone replacement is a once-a-day medication that requires less frequent dose adjustments and subsequently less frequent laboratory tests and doctor visits when compared to the treatment of Graves’ disease.