About Hypothyroidism
Hypothyroidism is a condition where the thyroid gland does not produce enough of one or both key hormones: T3 and T4. The thyroid regulates metabolism, and too little hormone can lead to several problems, including weight gain, fatigue and sensitivity to cold. There are several factors that can cause hypothyroidism, including disease, medical treatments and other conditions.
Diseases and Disorders
According to the Mayo Clinic, Hashimoto's thyroiditis, an autoimmune disease, is the most common cause of hypothyroidism. With autoimmune disorders, the body sees its own cells as foreign bodies, and the immune system attacks those cells. With Hashimoto's thyroiditis, the body attacks the thyroid, causing inflammation and damage, and the thyroid is no longer able to produce hormones.
Congenital disorders can cause hypothyroidism. In some cases, there are inherited disorders where the thyroid gland is defective, and in others a person may have no thyroid at all. In rare cases, pituitary disorders can also cause hypothyroidism. The pituitary produces TSH, a hormone that stimulates the thyroid to produce T3 and T4. A benign tumor on the pituitary can disrupt TSH production, leading to hypothyroidism.
Medical Causes
It is possible to produce too much thyroid hormone--a condition called hyperthyroidism--in those cases, a doctor will treat the disorder with radioactive iodine or anti-thyroid medications. In other cases, such as cancer, the doctor may remove all or part of the thyroid. These treatments actually kill some cells in the thyroid in an attempt to slow down hormone production. In some cases, the treatments do too much damage, and the result is hypothyroidism. Radiation therapy of the head and neck, for non-thyroid conditions, can also adversely affect the thyroid as can some medications, like lithium.
Other Conditions
The thyroid uses iodine to synthesize T3 and T4, and a deficiency of this mineral causes hypothyroidism and a condition called goiter. Iodine is usually found in seafood, plants grown in iodine-rich soil and seaweed. In many areas, iodine deficiency is common because people do not have access to the necessary nutrients. In the United States, the addition of iodine to table salt has virtually eliminated the problem. In some cases, adding iodine to the diet reverses this form of hypothyroidism. Some pregnant women develop gestational or postpartum hypothyroidism because they produce antibodies to their own thyroid gland. Gestational and postpartum hypothyroidism may be permanent, and it is essential that the woman seek treatment for her own health and the safety of her baby.
