Goiter

Most people with goiters have no signs or symptoms other than a swelling at the base of the neck. In many cases, the goiter is small enough that it’s only discovered during a routine medical exam or an imaging test for another condition.

Other signs or symptoms depend on whether thyroid function changes, how quickly the goiter grows and whether it obstructs breathing.

Underactive thyroid (hypothyroidism)

Signs and symptoms of hypothyroidism include:

• Fatigue.
• Increased sensitivity to cold.
• Increased sleepiness.
• Dry skin.
• Constipation.
• Muscle weakness.
• Problems with memory or concentration.

Overactive thyroid (hyperthyroidism)

Signs and symptoms of hyperthyroidism include:

• Weight loss.
• Rapid heartbeat (tachycardia).
• Increased sensitivity to heat.
• Excess sweating.
• Tremors.
• Irritability and nervousness.
• Muscle weakness.
• Frequent bowel movements.
• Changes in menstrual patterns.
• Sleep difficulty.
• High blood pressure.
• Increased appetite.

Children with hyperthyroidism might also have the following:

• Rapid growth in height.
• Changes in behavior.
• Bone growth that outpaces expected growth for the child’s age.

Obstructive goiter

The size or position of a goiter may obstruct the airway and voice box. Signs and symptoms may include:

• Difficulty swallowing.
• Difficulty breathing with exertion.
• Cough.
• Hoarseness.
• Snoring.

How the thyroid is regulated

The pituitary gland and hypothalamus control the rate at which T-4 and T-3 are produced and released.

The hypothalamus is a specialized region at the base of the brain. It acts as a thermostat for maintaining balance in multiple body systems. The hypothalamus signals the pituitary gland to make a hormone known as thyroid-stimulating hormone (TSH).

The pituitary gland — located below the hypothalamus — releases a certain amount of TSH, depending on how much T-4 and T-3 are in the blood. The thyroid gland, in turn, regulates its production of hormones based on the amount of TSH it receives from the pituitary gland.

Causes of goiter

A number of factors that influence thyroid function or growth can result in a goiter.

• Iodine deficiency. Iodine is essential for the production of thyroid hormones. If a person does not get enough dietary iodine, hormone production drops and the pituitary gland signals the thyroid to make more. This increased signal results in thyroid growth. In the United States, this cause is uncommon because of iodine added to table salt.
• Hashimoto’s disease. Hashimoto’s disease is an autoimmune disorder, an illness caused by the immune system attacking healthy tissues. The damaged and inflamed tissues of the thyroid don’t produce enough hormones (hypothyroidism). When the pituitary gland detects the decline and prompts the thyroid to create more hormones, the thyroid can become enlarged.
• Graves’ disease. Another autoimmune disorder called Graves’ disease occurs when the immune system produces a protein that mimics TSH. This rogue protein prompts the thyroid to overproduce hormones (hyperthyroidism) and can result in thyroid growth.
• Thyroid nodules. A nodule is the irregular growth of thyroid cells that form a lump. A person may have one nodule or several nodules (multinodular goiter). The cause of nodules is not clear, but there may be multiple factors — genetics, diet, lifestyle and environment. Most thyroid nodules are noncancerous (benign).
• Thyroid cancer. Thyroid cancer is less common than other cancers and generally treatable. About 5% of people with thyroid nodules are found to have cancer.
• Pregnancy. A hormone produced during pregnancy, human chorionic gonadotropin (HCG), may cause the thyroid gland to be overactive and enlarge slightly.
• Inflammation. Thyroiditis is inflammation of the thyroid caused by an autoimmune disorder, bacterial or viral infection, or medication. The inflammation may cause hyperthyroidism or hypothyroidism.