Hyperthyroidism is a condition where the body is making more thyroid hormone than the body needs. Thyroid hormone is important for growth and development, and instructs the body’s metabolism to speed up. If there is too much thyroid hormone circulating, metabolic rate continues to speed up, causing the person to feel unwell with the symptoms of hyperthyroidism.
The most common symptoms of hyperthyroidism are:
- Rapid heart rate
- Feeling hot and sweaty
- Increased appetite
- Weight loss, despite eating more
- Diarrhoea or frequent bowel movements
- Feeling anxious
- Difficulty sleeping
- Difficulty sitting still
- Difficulty concentrating
- A fine tremor or shake of the hands
- A lump or swelling in the middle of the neck, which moves with swallowing (called a goitre). This may be tender.
- Eyes appearing wide open or bulging
The most common cause of hyperthyroidism in children is an autoimmune condition known as Graves Disease. In Graves Disease, the person’s immune system has mistakenly made antibodies affecting thyroid gland. These antibodies bind to the Thyroid Stimulating Hormone (TSH) Receptors on the thyroid, and stimulate it to increase in size and produce more thyroid hormone. The gland can’t tell the difference between TSH from the pituitary, and antibodies produced by the immune system, as both turn the receptor ‘on’. The high circulating levels of the thyroid hormones T4 (thyroxine) and T3 (triiodothyronine) act throughout the body, increasing metabolic rate and leading to the symptoms of hyperthyroidism. The pituitary gland sees that there is too much thyroid hormone and stops making TSH, but while there are antibodies present they continue to bind to the receptor, telling the gland to make more hormone.
There are some other causes of hyperthyroidism that are more common in adults; these very rarely occur in children.
Hyperthyroidism can be diagnosed with a combination of physical examination and blood tests looking at the TSH, thyroid hormones, and antibodies. Your doctor will also check an ECG.
Children with hyperthyroidism should be referred to a paediatric endocrinologist for further investigation and management.
Treatment for hyperthyroidism involves giving medicine (tablets) to block or reduce production of excess thyroid hormone. Often it also involves medicines to lower heart rate, though these can usually be stopped once the thyroid hormone is under control. Blood tests to monitor the response to medication and assist with dose adjustments will be required.
Other treatment options for hyperthyroidism include surgery to remove the thyroid gland, or nuclear medicine treatment with radioiodine to ablate the thyroid gland. It is common to require life-long thyroid hormone replacement treatment with thyroxine after these procedures.