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Monday, December 9, 2013
A goiter is simply a thyroid gland that has grown to an abnormally large size. Some patients with goiter have a thyroid gland that is making too little thyroid hormone. An example of this would be Hashimoto's thyroiditis. Other patients with an abnormally large thyroid may have a gland that is overactive. For instance, patients with Graves' disease usually have an enlarged thyroid. However, many people have a goiter and yet have perfectly normal thyroid hormone levels in their blood. The thyroid is enlarged but it is making a normal amount of thyroid hormone.
There could be many different causes of goiters in people who do not have thyroid problems.
Often, when a patient has a goiter with normal thyroid hormone levels, the doctor is never really able to find out the exact cause of the goiter.
The most important part of the evaluation of a goiter is the doctor's examination. Commonly the doctor will evaluate a goiter using some or all of the following techniques:
By feeling the thyroid, the doctor can estimate the size of the gland, tell whether it is growing or not, and tell if it has any lumps in it that might be suspicious for cancer.
Measurement of the levels of thyroid stimulating hormone (TSH) and T4 in the blood stream are important because they help the doctor determine whether or not the goiter is making a normal amount of thyroid hormone.
If the gland has a lump in it, the doctor may order a thyroid scan or an ultrasound to see if there are any masses in the thyroid that might be suspicious for a thyroid cancer.
A thyroid scan is performed by having the patient take oral capsules that contain a harmless radioactive tracer (which is a tiny quantity of radioactive iodine). After four, six, or twenty-four hours (depending on the institution) a detector is placed over the thyroid gland. The amount of radioactive iodine that wound up in the thyroid gland is measured and a picture is taken of the distribution of radioactive iodine in the thyroid.
In a normal thyroid gland, radioactive iodine is taken up to the same degree throughout the entire gland. If there is an area of the thyroid that does not take up radioactive iodine well, then it must be further investigated. The majority of these "cold" areas on a thyroid scan are benign, but about 5-10% of them are thyroid cancers. Under such circumstances an ultrasound might be ordered.
Ultrasound is a way of taking a picture of the inside of the thyroid. Ultrasound bounces sound waves off the thyroid and makes a picture out of the returning echoes. If the ultrasound shows a large mass that is suspicious for cancer, then the ultrasonographer can use the ultrasound to guide a needle into the mass to perform a fine needle aspiration biopsy. If there are no large lumps in the thyroid gland that are suspicious for cancer, then no biopsy needs to be done.
A goiter may not need treatment if it is small and not growing. Treatment would be necessary for the following reasons:
If the thyroid were large enough to press on the swallowing tube, breathing tube, or nerve to the voice box, this pressure might cause difficulty swallowing, shortness of breath, or hoarseness in the voice. It might be important to treat a goiter that was growing in order to keep it from eventually pressing on these important structures and causing symptoms. Finally, if the goiter is large enough to be unsightly, the patient might want it treated for cosmetic reasons.
The best treatment for a goiter is a subtotal thyroidectomy. This is an operation in which most of the thyroid gland is removed. There are some research studies suggesting that putting a patient on a thyroid hormone pill everyday may help to shrink goiters or keep them from growing. However, there are other studies suggesting that this may not work. There are also studies suggesting that even a mild overdose of thyroid hormone, if taken for many years, can result in osteoporosis and may put older individuals at risk for abnormal heart rhythms.
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Last Reviewed: Mar 25, 2013
Thomas A Murphy, MD, FACP, FACE
Associate Professor of Medicine
School of Medicine
Case Western Reserve University