Thyroid problems: Causes, diagnosis and treatment
What are thyroid problems?
Problems with the thyroid include overactive thyroid, or hyperthyroidism, and underactive thyroid or hypothyroidism.
The thyroid gland in the neck makes hormones to help regulate the body's metabolism and a person's growth.
An overactive thyroid can make a person feel nervousness or anxious, be hyperactive and experience unexpected weight loss.
An underactive thyroid can make a person feel tired, put on weight and feel depressed.
Other thyroid disorders may cause a harmless swelling, or goitre, and thyroid cancer.
Picture of the thyroid
The thyroid is a butterfly-shaped gland that sits low on the front of the neck. Your thyroid lies below your Adam’s apple, along the front of the windpipe. The thyroid has two side lobes, connected by a bridge (isthmus) in the middle. When the thyroid is its normal size, you’re unlikely to be able to feel it.
What causes thyroid problems?
All types of hyperthyroidism are due to overproduction of thyroid hormones, but the condition can develop in several ways:
Graves' disease. This is an auto-immune condition and is the commonest cause of an overactive thyroid gland.
Toxic adenomas. Nodules develop in the thyroid gland and begin to secrete thyroid hormones, upsetting the body's chemical balance. Some goitres may contain several of these nodules.
Subacute thyroiditis. This is where inflammation of the thyroid causes the gland to ‘leak’ excess hormones, resulting in temporary hyperthyroidism. The condition generally lasts a few weeks, but it may persist for months.
Pituitary gland malfunctions or cancerous growths in the thyroid gland. In rare cases, hyperthyroidism can also be due to these causes.
Hypothyroidism, by contrast, stems from an underproduction of thyroid hormones. Since your body's energy systems require certain amounts of thyroid hormones, a drop in hormone production leads to lower energy levels. Causes of hypothyroidism include:
Hashimoto's disease. In this autoimmune disorder, the body’s own immune system attacks thyroid tissue, leading to reduced thyroid hormone.
Removal of the thyroid gland. The thyroid may be surgically removed or chemically destroyed as a treatment for hyperthyroidism.
Exposure to excessive amounts of iodide. Cold and sinus medicines, the heart medicine amiodarone or certain contrast dyes given before X-rays may expose you to too much iodine. You may then be at greater risk of developing hypothyroidism, especially if you have had thyroid problems in the past.
Lithium. This drug has also been linked to hypothyroidism.
Left untreated for long periods, hypothyroidism can bring on a myxoedema coma, a rare but potentially fatal condition that requires immediate hormone injections.
Hypothyroidism poses a special danger to newborns and infants. A lack of thyroid hormones in the system at an early age can result in cretinism (mental retardation) and dwarfism (stunted growth). Most infants now have their thyroid levels checked routinely soon after birth. If they are found to be hypothyroid, treatment begins immediately. In infants, as in adults, hypothyroidism can be due to these causes:
- A pituitary disorder
- A defective thyroid
- Complete lack of the gland
A hypothyroid infant is unusually inactive and quiet, has a poor appetite and sleeps for excessively long periods of time.
Cancer of the thyroid gland is quite rare and occurs in fewer than 10% of thyroid nodules. You may have one or more thyroid nodules for several years before they are determined to be cancerous. People who have received radiation treatment to the head and neck earlier in life tend to have a higher than normal propensity for developing thyroid cancer.