Definition
Hyperthyroidism is a condition caused by an overactive thyroid gland. The gland makes too much T4 and T3 hormones. 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 which control the way that every cell in the body uses energy (metabolism). The thyroid is part of the endocrine system.
Hyperthyroidism or thyrotoxicosis occurs when the thyroid releases too many of its hormones over a short (acute) or long (chronic) period of time. Many diseases and conditions can cause this problem, including:
- Graves disease
- Non-cancerous growths of the thyroid gland or pituitary gland
- Tumors of the testes or ovaries
- Inflammation (irritation and swelling) of the thyroid due to viral infections or other causes
- Ingestion (taking in through the mouth, such as in eating) of large amounts of thyroid hormone
- Ingestion of excessive iodine
Graves disease accounts for 85% of all cases of hyperthyroidism.
Related topics:
- Painless (silent) thyroiditis
- Factitious hyperthyroidism
- Hypothyroidism
- Graves disease
Symptoms
Additional symptoms that may be associated with this disease:
Signs and tests
Physical examination may reveal thyroid enlargement or goiter. Vital signs (temperature, pulse, rate of breathing, blood pressure) show 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 is usually low
- T3 and free T4 are usually high
This disease may also alter the results of the following tests:
- Vitamin B-12
- TSI
- Triglycerides
- RT3U
- Radioactive iodine uptake
- Glucose test
- Cholesterol test
- Antithyroglobulin antibody
Treatment
Treatment varie
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