Hypothyroidism is a disease caused by a reduction in the production of the two hormones produced by the thyroid. These hormones regulate almost all bodily functions and the lack of these in the body leads to a number of symptoms related to metabolism. Sufferers may suffer a few or all of the symptoms. If untreated, the symptoms get worse and, if they become very serious, can lead to extremely low blood pressure and death. People who have a family history of the disease are more likely to get it. It does not commonly affect males or women under the age of 50.
The only distinct sign of the disease is goiter - an enlargement of the thyroid gland that causes noticeable swelling in the neck. Goiters can become quite large if the disease is untreated.
Hypothyroidism can be the result of three major underlying causes:
- A lack of iodine in the diet. Iodine is required to make the thyroid hormones. In most countries, iodine is added to table salt and this cause is now rare, although it is common in less developed nations.
- A malfunctioning pituitary gland. The pituitary signals the thyroid to release its hormones and if it is malfunctioning, the thyroid gland will not function either.
- Damage to the thyroid gland, which can often be caused by radiation treatment with iodine for certain types of cancers, as well as treatments for the opposite condition - hyperthyroidism.
A less common cause is Hashimoto's thyroiditis - an autoimmune condition.
In all cases, the treatment is the same - giving the patient synthetic hormones.