Hyperthyroidism, or overactive thyroid, is a condition where the thyroid makes too much thyroxine, or T4. There are several possible causes for this. One is Graves' disease. Another is a lump or nodule on the thyroid that is hyperactive. Thyroiditis, or inflammation of the thyroid, is a condition where the thyroid leaks T4, and may come about naturally or from taking too high a dose of synthetic thyroid hormones or an iodine supplement. Tumors on the testes or ovaries can also cause hyperthyroidism.
Rapid Heartbeat and Tremors
Hyperthyroidism can cause symptoms such as a rapid heartbeat, tremors and nervousness. A rapid heartbeat is called tachycardia, and the heart may beat more than 100 beats per minute. A person suffering from hyperthyroidism symptoms may also notice palpitations and irregular beats. Tremors are often noticed when the hands begin to tremble slightly. Nervousness, restlessness and anxiety are common. A person with an overactive thyroid may have difficulty concentrating and staying on task, and may also find it hard to sleep, which can contribute to the common symptom of fatigue. Sweating more than usual is also common.
Digestive and Muscular Symptoms
An overactive thyroid can cause excessive hunger. Even though a patient may be eating more, he may lose weight. Rarely, a hyperthyroidism patient will gain weight. Some people have nausea and vomiting, and many experience bowel movements that are more frequent than usual. Hyperthyroidism can cause muscular weakness. This is often noticed in the upper arms and thighs.
Goiter and Protruding Eyeballs
A goiter, or enlarged thyroid gland, is a lump in the base of the neck. Sometimes people with hyperthyroidism caused by Graves' disease experience Graves' ophthalmopathy, which is the protrusion of one or both eyeballs. With this condition, eye dryness, redness, swelling and discomfort is common.
Other Symptoms
In women, an overactive thyroid can cause menstrual irregularity or even the ceasing of menstrual periods. Hair loss can occur in both men and women. High blood pressure is a symptom of hyperthyroidism. Some patients experience itching all over the body. A physician may detect hyperactive reflexes during a medical exam in hyperthyroidism patients.
