Definition
Hyperthyroidism is a condition in which the thyroid gland is overactive, and makes too much thyroid hormone (called thyroxine [T4 ] and triiodothyronine [T3 ]). Hormones are substances that affect and control many important functions in the body.
Alternative Names
Thyrotoxicosis; Overactive thyroid
Causes, incidence, and risk factors
The thyroid gland is located in the neck. It produces several hormones that control the way every cell in the body uses energy (metabolism). The thyroid is part of the endocrine system.
Hyperthyroidism occurs when the thyroid releases too much of its hormones over a short (acute) or long (chronic) period of time. Many diseases and conditions can cause this problem, including:
- Getting too much iodine
- Graves disease
- Inflammation (irritation and swelling) of the thyroid due to viral infections or other causes
- Non-cancerous growths of the thyroid gland or pituitary gland
- Taking large amounts of thyroid hormone
- Tumors of the testes or ovaries
Graves disease accounts for 85% of all cases of hyperthyroidism.
Related topics:
Symptoms
- Difficulty concentrating
- Fatigue
- Frequent bowel movements
- Goiter (visibly enlarged thyroid gland) or thyroid nodules
- Heat intolerance
- Increased appetite
- Increased sweating
- Irregular menstrual periods in women
- Nervousness
- Restlessness
- Weight loss (rarely, weight gain)
Other symptoms that can occur with this disease:
- Bounding pulse
- Breast development in men
- Clammy skin
- Diarrhea
- Hair loss
- Hand tremor
- Weakness
- High blood pressure
- Itching - overall
- Lack of menstrual periods in women
- Nausea and vomiting
- Protruding eyes (exophthalmos)
- Rapid, forceful, or irregular heartbeat (palpitations)
- Skin blushing or flushing
- Sleeping difficulty
Signs and tests
Physical examination may reveal thyroid enlargement, goiter, or an increased heart rate. Systolic blood pressure (the first number in a blood pressure reading) may be high.
Laboratory tests that evaluate thyroid function:
- Serum TSH (thyroid stimulating hormone) is usually low
- T3 and free T4 are usually high
This disease may also affect the results of the following tests:
Treatment
How the condition is treated depends on the cause an
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