Hyperthyroidism
Hyperthyroidism is a medical condition characterized by an excess of the hormone thyroxine in the body, primarily caused by an overactive thyroid gland. This condition can lead to various symptoms, including rapid heart rate, weight loss despite increased appetite, heat sensitivity, anxiety, and muscle weakness. It may also manifest through physical signs such as a goiter or swelling at the base of the neck. Common causes include Graves' disease, toxic nodules, and, in some cases, excessive intake of synthetic thyroxine. Diagnosis typically involves blood tests measuring thyroid hormone levels and TSH, along with imaging procedures like a thyroid scan. Treatment options include antithyroid medications, radioactive iodine therapy, or surgical intervention to manage the thyroid's function. While hyperthyroidism predominantly affects younger women, its symptoms may be less pronounced in older adults. Awareness of this condition is vital for timely diagnosis and management, as untreated hyperthyroidism can lead to significant health complications.
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Hyperthyroidism
Hyperthyroidism is a medical condition in which the human body contains too much of a hormone called thyroxine. The most common cause for this condition is a problem with the thyroid gland that causes the body to produce too much thyroxine, but it can also result from an infection or from ingesting too much synthetic thyroxine. A person with hyperthyroidism will experience a number of symptoms, including cardiovascular issues and problems with food metabolism. Hyperthyroidism can be treated with medication or, in some cases, with surgery.
Overview
The major functions of the human body are controlled by the endocrine system, which is a system of glands that make, store, and release hormones. Hormones are substances that help regulate the body's other systems. The thyroid is a butterfly-shaped gland weighing less than an ounce that is located at the base of the throat. It produces two hormones, thyroxine, also known as T-4, and triiodothyronine, also known as T-3. These hormones play a key role in heart rate and function and in controlling the body's temperature. Together, they regulate how food is metabolized to provide energy. They do this by controlling how the body uses carbohydrates and fats, how much protein the body produces, and how much calcium is released into the bloodstream. As a result, these two hormones have an effect on every part of the body.
The main glands of the endocrine system, the hypothalamus and the pituitary gland, control the amount of T-3 and T-4 made and released by the thyroid. When the body is in need of these hormones, the hypothalamus signals the pituitary gland to release thyroid stimulating hormone, or TSH. TSH then tells the thyroid to release the appropriate hormones. Sometimes the process goes wrong, and the thyroid produces and releases the incorrect amounts of hormones. Infection, injury, or the ingestion of too much synthetic thyroid hormone can also interfere with the process. When a person has too much thyroxine in his or her system for any of these reasons, it results in a condition known as hyperthyroidism.
Symptoms, Causes, and Treatments
Thyroxine helps to regulate several of the body's systems, so hyperthyroidism is often revealed by disruptions to these systems. A person might experience tachycardia, or a heart rate of more than one hundred beats per minute. The heart rate may also be irregular, a condition known as arrhythmia, or it may feel like the heart is pounding, which doctors refer to as palpitations.
Too much thyroxine can cause sudden weight loss. This can happen despite the fact that increased appetite is also a sign of hyperthyroidism. In addition, the hormone's effect on temperature regulation might cause a person with hyperthyroidism to be more sensitive to heat and to sweat more. Other symptoms of hyperthyroidism include anxiety and nervousness, difficulty sleeping, fatigue, muscle weakness, a change in bowel habits, trembling hands, brittle hair, thinning skin, and the development of a goiter, or swelling, at the base of the neck. However, some older adults may not experience many of these symptoms or may experience them to a lesser degree. Some medications, most notably beta-blockers used for blood pressure control, may mask the symptoms and make them less obvious.
Some patients with hyperthyroidism experience a condition called Graves' ophthalmopathy. In these cases, the muscles behind the eye swell to the extent that the eyeball is pushed outside of the normal eye socket. This can cause the eye to become very dry and lead to redness, swelling, tearing, and irritation of the eye. This condition is more common in smokers.
About 70 percent of hyperthyroidism cases are the result of a condition known as Graves' disease. In this condition, antibodies in the blood attack the entire thyroid, causing it to grow larger than normal and release too much thyroxine. While the cause of Graves' disease is not known, it does tend to run in families and is more likely to affect younger women.
Sometimes nodules, or small lumps of tissue, grow in and around the thyroid. These nodules can cause the thyroid to release more thyroxine than normal. This condition is known as a toxic nodule or multinodular goiter.
In some cases, people can develop temporary hyperthyroidism due to an infection that interferes with the thyroid's function for a short period. This is called thyroiditis. Additionally, sometimes people who have been prescribed a synthetic or artificial form of thyroxine as treatment for low thyroid function (hypothyroidism) might inadvertently take too high a dose. This also results in a temporary form of hyperthyroidism. High thyroxine levels from unintentional ingestion of too much thyroxine is also known as thyrotoxicosis. This differentiates this type of hyperthyroidism from the type caused by a malfunction of the thyroid gland.
If hyperthyroidism is suspected, a medical professional will check the patient's heart rate and look for telltale signs of the condition, such as an enlargement of the thyroid gland, moist and smooth skin, eye abnormalities, and tremors. Simple blood tests can assess the levels of thyroid hormone and TSH in the patient's system. When tests reveal low levels of TSH but high levels of thyroxine, or T-4, hyperthyroidism is likely present. This can be confirmed with an imaging procedure known as a thyroid scan. A thyroid uptake test, which checks how the thyroid processes iodine, may also be ordered to check the gland's functions.
Once hyperthyroidism is diagnosed, there are several ways to treat it. Some patients will be given antithyroid agents such as methimazole or propylthiouracil (PTU). These drugs stop the thyroid from making more thyroxine. In other cases, the patient will be given a single dose of radioactive iodine in capsule form. This will be absorbed by the overactive cells in the thyroid and will destroy them over the course of several weeks or months. The goal is to allow the thyroid to return to normal size and function. Antithyroid drugs and beta-blockers may be used during this time and even after to control any resulting symptoms of hyperthyroidism.
However, in some cases it is necessary to prevent any future recurrences of the condition. In these cases, a second dose of radioactive iodine may be given to destroy the thyroid or the thyroid may be removed or reduced in size surgically. This will result in too little thyroxine being released, a condition known as hypothyroidism, but this is easily treated with daily administration of synthetic thyroxine.
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