Hyperthyroidism (overactive thyroid)


The butterfly-shaped thyroid gland is at the front of the neck, just below the Adam’s apple. It secretes thyroxine, the key hormone of metabolism. It controls how quickly calories are burned, as well as affecting heart rate and other functions of the body. In hyperthyroidism, the gland secretes too much thyroxine, causing rapid weight loss. The excess thyroxine accelerates the heart rate and may cause an irregular beat, sweating, nervousness, hand tremors and trouble sleeping. There are several treatments available, including medications and/or radioactive iodine to slow down the production of thyroxine. Sometimes all or part of the gland must be surgically removed. Most people respond well to treatment.

Symptoms and Diagnosis

Hyperthyroidism starts slowly, with symptoms much like many other health problems. It may be mistaken for stress. As it progresses, weight loss becomes rapid, even with increased appetite and food consumption and the usual activity level. The heart rate may be greater than 100 beats per minute (normal 60-100) and the rhythm irregular and/or pounding. Nervousness, anxiety, feeling overheated with unusually heavy sweating, sleeplessness, fatigue, weakness, and hand tremors may be present. More frequent bowel movements and changes in the menstrual cycle may occur. The gland may be easily felt or a bulge (goiter) seen. Hair may become fine and brittle. Symptoms in older adults are more subtle, and fewer; an increased heart rate and feeling tired may be the only symptoms. Beta-blockers, a class of medication used to treat high blood pressure may mask the symptoms of hyperthyroidism. One type of hyperthyroidism is associated with Grave’s ophthalmopathy, in which the eyeballs bulge out of the usual position, become red, irritated, and tear excessively, with increased light sensitivity and blurry vision.

To make the diagnosis, the doctor will check for an enlarged thyroid gland, rapid pulse, a tremor, moist skin, eye changes and overactive reflexes. Blood tests are performed for several hormones associated with thyroid function. If hyperthyroidism is present your doctor may order a radioactive iodine test, which shows if the entire gland is enlarged or if one or more nodules are the source of excess thyroxine.


The thyroid gland weighs only an ounce, but has an enormous effect on every function of the human body. It regulates all aspects of metabolism, including a key role in calcium regulation. The most common type of hyperthyroidism is Grave’s disease, an autoimmune disorder, in which the immune system makes cells that attack the thyroid tissue. Another type of thyroid disease is called toxic adenoma, toxic multinodular goiter, or Plummer’s disease, in which excess thyroxine is secreted by one or more nodules. They are not cancerous; it’s unknown why the nodules overproduce thyroid hormones. Thyroiditis is a generalized swelling of the gland, usually caused by the immune system or a viral infection. Hyperthyroidism, especially Grave’s disease, runs in families, and is more common in women than in men. Continue reading for Prevention and Treatment Information . . .

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