Hyperthyroidism occurs when the thyroid gland overproduces thyroid hormone. The thyroid is an organ that regulates the metabolism — the way the body uses energy — and many other essential body functions. Two hormones produced by the thyroid are thyroxine (T4) and triiodothyronine (T3). These hormones control metabolism, breathing, heart rate, nervous system, weight, body temperature, and more. A healthy thyroid releases the right amount of hormones to maintain the normal functioning of vital body processes. Left untreated, a diseased thyroid (hyperactive or underactive) can cause serious health problems.
Risk Factors for Hyperthyroidism
- Being female. Hyperthyroidism is more common in women
- Heredity. Hyperthyroidism tends to run in families.
- Having a previous thyroid condition
An overactive thyroid speeds up the body's processes, which may cause nervousness, anxiety, rapid heartbeat, hand tremors, excessive sweating, weight loss, and insomnia.
Causes of Hyperthyroidism
Graves’ disease
The most common cause of hyperthyroidism is an autoimmune disorder called Graves' disease. Graves' Disease occurs when the thyroid gland makes too much of thyroid-stimulating immunoglobin (TSI). In this case the entire thyroid is overactive. Graves' disease is genetic and is more common in women.
Thyroid Nodules
Noncancerous lumps or nodules can also cause hyperthyroid disease. These lumps, called adenomas, can cause the thyroid to produce too much of the T4 thyroid hormone. In this case it is usually one single nodule that is overactive. On rare occasions there may be more than one overactive nodule.
Pregnancy
Women may develop hyperthyroidism during pregnancy or within the first year after giving birth. Around 20% of postpartum hyperthyroidism is permanent.
Inflammation
The thyroid can become inflamed for known and unknown reasons. An inflamed thyroid can produce too much thyroid hormone.
Signs and Symptoms of Hyperthyroidism
Patients suspected of hyperthyroidism may present with:
- Sudden or unexplained weight loss
- Nervousness and anxiety
- Hand tremors
- Rapid heartbeat
- Fever
- Skin irritation, such as dryness, redness or swelling
- Diarrhea or increased frequency of bowel movements
- Insomnia
- Mood swings
- Menstrual changes
Diagnosis of Hyperthyroidism
Patients suspected of having hyperthyroidism will first undergo a complete physical examination and medical history.
The following diagnostic tests may be ordered:
Blood tests
Measure thyroid stimulating hormone (TSH) and T3 and 4 hormone levels.
Imaging tests
- Ultrasound of the neck if nodules or inflammation is present
- A thyroid scan, using small amounts of radioactive material
Thyroid uptake
Uses radioactive iodine contrast to measure thyroid function. This can help distinguish between the different causes of hyperthyroidism.
