Disease: Thyroid nodules

Overview

Thyroid nodules are solid or fluid-filled lumps that form within your thyroid, a small gland located at the base of your neck, just above your breastbone.

The great majority of thyroid nodules aren't serious and don't cause symptoms. Thyroid cancer accounts for only a small percentage of thyroid nodules.

You often won't know you have a thyroid nodule until your doctor discovers it during a routine medical exam. Some thyroid nodules, however, may become large enough to be visible or make it difficult to swallow or breathe.

Treatment options depend on the type of thyroid nodule you have.

Source: http://www.mayoclinic.com

Symptoms

Most thyroid nodules don't cause signs or symptoms. Occasionally, however, some nodules become so large that they can:

  • Be felt
  • Be seen, often as a swelling at the base of your neck
  • Press on your windpipe or esophagus, causing shortness of breath or difficulty swallowing

In some cases, thyroid nodules produce additional thyroxine, a hormone secreted by your thyroid gland. The extra thyroxine can cause symptoms of hyperthyroidism such as:

  • Unexplained weight loss
  • Increased perspiration
  • Tremor
  • Nervousness
  • Rapid or irregular heartbeat

A few thyroid nodules are cancerous (malignant), but determining which nodules are malignant can't be done by symptoms alone. Most cancerous thyroid nodules are slow growing and may be small when they're discovered. Aggressive thyroid cancers are rare, but these nodules may be large, firm, fixed and rapid growing.

When to see a doctor

Although most thyroid nodules are noncancerous (benign) and don't cause problems, ask your doctor to evaluate any unusual swelling in your neck, especially if you have trouble breathing or swallowing. It's important to evaluate the possibility of cancer.

Also seek medical care if you develop signs and symptoms of hyperthyroidism, such as:

  • Sudden weight loss even though your appetite is normal or has increased
  • A pounding heart
  • Trouble sleeping
  • Muscle weakness
  • Nervousness or irritability

Source: http://www.mayoclinic.com

Causes

Several conditions can cause nodules to develop in your thyroid gland:

  • Iodine deficiency. Lack of iodine in your diet can sometimes cause your thyroid gland to develop thyroid nodules. But iodine deficiency is uncommon in the United States, where iodine is routinely added to table salt and other foods.
  • Overgrowth of normal thyroid tissue. Why this occurs isn't clear, but such a growth — which is sometimes referred to as a thyroid adenoma — is noncancerous and isn't considered serious unless it causes bothersome symptoms from its size.

    Some thyroid adenomas (autonomous or hyperfunctioning thyroid nodules) produce thyroid hormones outside of your pituitary gland's normal regulatory influence, leading to an overproduction of thyroid hormones (hyperthyroidism).

  • Thyroid cyst. Fluid-filled cavities (cysts) in the thyroid most commonly result from degenerating thyroid adenomas. Often, solid components are mixed with fluid in thyroid cysts. Cysts are usually benign, but they occasionally contain malignant solid components.
  • Chronic inflammation of the thyroid (thyroiditis). Hashimoto's disease, a thyroid disorder, can cause thyroid inflammation resulting in nodular enlargement. This often is associated with reduced thyroid gland activity (hypothyroidism).
  • Multinodular goiter. "Goiter" is a term used to describe any enlargement of the thyroid gland, which can be caused by iodine deficiency or a thyroid disorder. A multinodular goiter contains multiple distinct nodules within the goiter, but its cause is less clear.
  • Thyroid cancer. Although the chances that a nodule is malignant are small, certain factors increase your risk of thyroid cancer, such as a family history of thyroid or other endocrine cancers. Other risk factors include being younger than 30 or older than 60, being a male, or having a history of radiation exposure, particularly to the head and neck. A nodule that is large and hard or causes pain or discomfort is more worrisome in terms of malignancy.

Source: http://www.mayoclinic.com

Diagnosis

In assessing a lump or nodule in your neck, one of your doctor's main goals is to rule out the possibility of cancer. But your doctor will also want to know if your thyroid is functioning properly. Tests include:

  • Physical exam. You'll likely be asked to swallow while your doctor examines your thyroid because a nodule in your thyroid gland will usually move up and down during swallowing.

    Your doctor will also look for signs and symptoms of hyperthyroidism, such as tremor, overly active reflexes, and a rapid or irregular heartbeat; and signs and symptoms of hypothyroidism, such as a slow heartbeat, dry skin and facial swelling.

  • Thyroid function tests. Tests that measure blood levels of thyroxine and triiodothyronine, hormones produced by your thyroid gland, and thyroid-stimulating hormone (TSH), which is released by your pituitary gland, can indicate whether your thyroid is producing too much thyroxine (hyperthyroidism) or too little (hypothyroidism).
  • Ultrasonography. This imaging technique uses high-frequency sound waves rather than radiation to produce images. It provides the best information about the shape and structure of nodules. It may be used to distinguish cysts from solid nodules or to determine if multiple nodules are present. It may also be used as a guide in performing a fine-needle aspiration biopsy.
  • Fine-needle aspiration (FNA) biopsy. Nodules are often biopsied to make sure no cancer is present. FNA biopsy helps to distinguish between benign and malignant thyroid nodules. During the procedure, your doctor inserts a very thin needle in the nodule and removes a sample of cells.

    The procedure, which is carried out in your doctor's office, takes about 20 minutes and has few risks. Often, your doctor will use ultrasound to help guide the placement of the needle. The samples are then sent to a laboratory and analyzed under a microscope.

  • Thyroid scan. In some cases, your doctor may recommend a thyroid scan to help evaluate thyroid nodules. During this test, an isotope of radioactive iodine is injected into a vein in your arm. You then lie on a table while a special camera produces an image of your thyroid on a computer screen.

    Nodules that produce excess thyroid hormone — called hot nodules — show up on the scan because they take up more of the isotope than normal thyroid tissue does.

    Cold nodules are nonfunctioning and appear as defects or holes in the scan. Hot nodules are almost always noncancerous, but a few cold nodules are cancerous. The disadvantage of a thyroid scan is that it can't distinguish between benign and malignant cold nodules.

    The length of a thyroid scan varies, depending on how long it takes the isotope to reach your thyroid gland. You may have some neck discomfort because your neck is stretched back during the scan, and you'll be exposed to a small amount of radiation.

Source: http://www.mayoclinic.com

Complications

Complications associated with thyroid nodules include:

  • Problems swallowing or breathing. Large nodules or a multinodular goiter — an enlargement of the thyroid gland containing several distinct nodules — can interfere with swallowing or breathing.
  • Hyperthyroidism. Problems can occur when a nodule or goiter produces thyroid hormone, leading to hyperthyroidism. Hyperthyroidism can result in weight loss, muscle weakness, heat intolerance, and anxiousness or irritability.

    Potential complications of hyperthyroidism include an irregular heartbeat (atrial fibrillation); weak bones (osteoporosis); and thyrotoxic crisis, a sudden and potentially life-threatening intensification of signs and symptoms that requires immediate medical care.

  • Problems associated with thyroid cancer. If a thyroid nodule is cancerous, surgery is usually required. Generally, most or all of your thyroid gland is removed, after which you'll need to take thyroid hormone replacement therapy for the rest of your life.

Source: http://www.mayoclinic.com

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