Underactive thyroid is a condition known as hypothyroidism, characterized by reduced secretion of the hormone thyroxine. The result is insufficient amounts of this hormone in the blood which causes symptoms like weakness, fatigue, hair loss, weight gain, muscle cramps and aches, insomnia, and rapid heart rate. But, do you know what the causes of this thyroid disorder are?
Here are the 8 most common causes of hypothyroidism:
1. Autoimmune Disease
One of the most common causes of hypothyroidism is the autoimmune disease known as Hashimoto’s thyroiditis. This disease is caused by inflammation of the thyroid gland and happens when a person’s immune system attacks their own thyroid gland. Even though it’s still unknown why the body would attack its own tissues, some believe the reason is a bacterium or virus, while others think it’s some genetic flaw.
Nevertheless, autoimmune diseases occur because of more than one factor. Regardless of the true reason, these antibodies influence the secretion of the thyroid hormones.
2. Treatment of Hyperthyroidism
The treatment of hyperthyroidism – overactive thyroid, usually involves anti-thyroid medications or radioactive iodine to slow down and normalize the thyroid function. But, sometimes this treatment can result in permanent hypothyroidism. A person will need a proper thyroid treatment if their thyroid gland has been removed, if they had undergone radiation therapy, or if the cause of their hypothyroidism is Hashimoto’s thyroiditis.
3. Thyroid Surgery
Although not as common as radioactive iodine or antithyroid medications, surgery is still an option for treating hypothyroidism. This surgery is called thyroidectomy where the thyroid gland is removed partially or completely. For instance, thyroid surgery caused by a solitary toxic adenoma requires partial removal of the gland, while that caused by Graves’ disease requires a complete removal.
4. Radiation Therapy and Medications
In some cases, radiation therapy for head and neck cancers can affect the function of the thyroid gland, causing hypothyroidism. The radiation of this parts of your body can damage the thyroid cells, impeding the production of the thyroid hormone. Also, numerous medications can contribute to reduced secretion of the thyroid hormone, such as lithium.
5. Congenital Disease
Sometimes, babies can be born without a thyroid gland or with a defective one. Even though rarely, some kids have inherited form of the thyroid disorder, including congenital hypothyroidism which is lack of the thyroid hormone. Nowadays, 1 in 4,000 babies is born with a severe deficiency of the thyroid hormone, and there are even more with partial or mild deficiency. If the severe congenital hypothyroidism is not treated within few months after birth, it can cause permanent intellectual disability and growth failure.
6. Pituitary Disorder
This disorder is a rather rare cause of hypothyroidism, but we still must mention it. It happens when the tiny gland located at the base of the brain called pituitary gland fails to secrete enough of the thyroid-stimulating hormone. The function of this gland is to secrete hormones which stimulate the production of many important hormones in the body, including the thyroid hormone.
Pregnant women with an undetected mild thyroid disorder can suddenly experience noticeable symptoms of hypothyroidism. This is because while pregnant, the woman’s body needs sufficient amounts of thyroid hormone to not only support her increased metabolic needs but also to that of the developing fetus. But, if the woman has an already overtaxed thyroid gland or Hashimoto’s thyroiditis, her levels of thyroid hormone can drop further.
Women with healthy thyroid gland shouldn’t have such problem, even though there are rare cases of women experiencing underactive thyroid during or after pregnancy. This is because their bodies produce antibodies which attack their thyroid gland. If this condition is not treated on time, it might lead to premature delivery or miscarriage.
8. Lack of Iodine
Iodine is one of the vital minerals for the secretion of thyroid hormones. If there’s lack of this mineral, the thyroid gland won’t be able to produce enough of the thyroid hormone. Besides hypothyroidism, lack of iodine can cause enlarged thyroid gland, while pregnant women with iodine deficiency can have children with mental retardation.
Since this mineral is not naturally produced in the human’s body, we have to consume foods rich in iodine, including seaweed, seafood, iodized salt, and plants grown in iodine-rich soil.