Thyroid Nodules
Simply put, a nodule is a lump. The vast majority of thyroid nodules are small, benign, and harmless. They may occur as a single nodule or as a clump. By some estimates, nodules occur in as much as half the population, often without symptoms or problems. Nodules are more common in women than men, and become more common with age.
Essential
Nodules are very common, especially among older adults. Among all adults aged fifty, half will have at least one thyroid nodule, according to EndocrineWeb.com. Among adults aged sixty, 60 percent will have at least one thyroid nodule. And in adults aged seventy, 70 percent will have at least one thyroid nodule.
Many people won't even notice they have a nodule until their doctor feels one in their throat during a routine physical. But if the nodule gets bigger, you may actually be able to see it on your throat as a lump in the lower front of your neck. Women may notice it when they're applying makeup or face cream. Men may feel it while they're shaving or notice that their shirt collars are becoming uncomfortably snug. Large nodules may actually press against your windpipe or your esophagus, making it difficult for you to breathe or swallow. Sometimes, these larger nodules can affect your voice and cause hoarseness.
Types of Nodules
At first glance, all nodules appear the same. But in reality, there are several different types of nodules. Some cause no problems, while others may cause minor problems. Still others can get rather large and churn out their own thyroid hormone, causing hyperthyroidism. The three main types of nodules are:
Toxic Adenomas: Also known as autonomous toxic nodules, toxic adenomas develop as a result of a genetic mutation in the thyroid follicular cell. Toxic adenomas produce their own thyroid hormone and can cause hyperthyroidism. We'll discuss these in more detail later.
Cysts: Cysts account for 15 to 25 percent of all nodules. Most cysts are filled only with fluid. Those that contain solid material as well as fluid are known as complex cysts. Large ones may need ongoing monitoring and evaluation.
Colloid Nodules: Colloid is the substance at the center of a thyroid cell. A colloid nodule is made up mostly of colloid. It is always benign and usually does not produce much, if any, thyroid hormone.
Nodules can produce annoying symptoms, but the vast majority of nodules are benign, with only a small percentage turning out to be malignant. For example, a single nodule in an otherwise healthy gland is more likely to be cancerous than a multinodular goiter. A nodule that is hard to the touch is another sign that your nodule may be cancerous. Nodules accompanied by enlargement of the lymph nodes in the neck may also indicate cancer. The bottom line is this:All nodules warrant medical attention and evaluation to pin down the exact cause and type of nodule.
A Look at Toxic Adenomas
Of all the different types of nodules, the ones that cause the most severe hyperthyroidism are the toxic adenomas, which develop as a result of an abnormality in the follicular cell of the thyroid. Normally, TSH receptors in the follicular cell require TSH to turn on the cell and trigger the production of thyroid hormone.
With toxic adenomas, a mutation causes the TSH receptor to be permanently turned on, even without TSH. As a result, thyroid hormone is produced in excess, and the cell multiplies and divides, eventually causing a nodule to form.
