An overactive thyroid can mimic an endless shot of adrenaline
When the thyroid gland pumps out too much hormone, the whole body speeds up: a racing heart, trembling hands, sweating, sleeplessness and weight loss even with a hearty appetite. The effect resembles an overdose of adrenaline. Worldwide, about 2.5 percent of adults have hyperthyroidism, and women are affected far more often.
Thyroid hormone is essential to how cells work. In excess it overdrives metabolism and unsettles the sympathetic nervous system, the body's accelerator. That explains the familiar picture: palpitations, tremor, anxiety, a hurried gut causing frequent bowel movements or diarrhoea, heat intolerance, thinning skin, brittle hair and weakness that is often worst in the upper arms and thighs. Blood tests may even show unusually low cholesterol. Not everyone fits the pattern, though. Some people have no symptoms, older people and pregnant women tend to have milder ones, and around 10 percent of those affected gain weight rather than lose it.
Doctors distinguish two terms. Thyrotoxicosis means raised thyroid hormone from any cause, so it includes hyperthyroidism, where the gland itself overproduces; some people use the words as if they were identical. In the United States, Graves' disease accounts for roughly 50 to 80 percent of cases. Other causes include lumpy multinodular goitres, single overactive nodules, thyroid inflammation, too much iodine or too much synthetic hormone, and more rarely a pituitary tumour. Blood tests typically show low thyroid-stimulating hormone alongside high T3 or T4, and scans or antibody tests help pin down the cause.
Treatment has three main routes, chosen according to cause and severity. Radioiodine therapy uses iodine-131 swallowed by mouth, which gathers in the thyroid and destroys it over weeks to months; the underactive thyroid that results is then managed with replacement hormone. Drugs such as methimazole can suppress hormone production for a time, and beta blockers ease symptoms. Surgery is another option, especially for very large glands or when cancer is suspected. A rare, dangerous complication called thyroid storm can follow a trigger such as infection, bringing confusion and high fever, and it is often fatal.
About 1.2 percent of Americans are affected. The condition usually begins between 20 and 50, is two to ten times more common in women, and overall is most frequent after 60.
Source: Hyperthyroidism
