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What Causes Hypothyroidism

What Causes Hypothyroidism

Damage to the thyroid gland during cancer treatment or intake of antithyroid medications can lead to hypothyroidism.
Nicks J
When the human body is incapable of producing thyroid hormones in adequate amounts, the condition is referred as hypothyroidism (underactive thyroid). The production of thyroid hormones (T3 and T4) is assigned to the thyroid gland, a butterfly shaped gland present in the neck area. The thyroid hormones do an important job of keeping the metabolic rate normal. So, with the onset of hypothyroidism, the body's metabolism will go haywire and trigger a wide range of health problems.
Symptoms
The symptoms are discussed below:
  • Fatigue
  • Dry skin
  • Constipation
  • High cholesterol
  • Muscle weakness
  • Weight gain
  • Joint inflammation
Causes
Hashimoto's Thyroiditis
This is one of the most common reasons behind diagnosis of hypothyroidism in both men and women. Swelling of the thyroid gland is the hallmark of Hashimoto's thyroiditis. Now, why does the thyroid gland gets inflamed? In this condition, the immune system commits the mistake of identifying the thyroid gland as a harmful foreign object. This incorrect identification stimulates the immune system to 'wage a war' against the thyroid gland. In other words, the defense mechanism of our body strikes the tissue of the thyroid gland, resulting in inflammation and subsequent low production of thyroid hormone.
Thyroid Gland Damage
Another reason behind the occurrence of hypothyroidism could be linked to thyroid gland damage. Patients taking treatment for hyperthyroidism (excess production of thyroid hormones) for quite some time are at an increased risk of suffering from damage, including complete destruction of the thyroid gland. Hyperthyroidism treatment involves use of antithyroid medications that do not allow the thyroid gland to produce hormone in surplus amounts. The amount of time the medication will be taken usually varies from 12 to 18 months. This long-term use can suppress the thyroid gland so much so that it can cause lifelong hypothyroidism.
Iodine Deficiency
Following a diet low in iodine can also cause hypothyroidism. The presence of iodine in adequate amounts is very essential for normal thyroid activity. Without iodine, it is very difficult for the thyroid gland to manufacture hormones. Hence, low iodine can result in hypothyroidism. Simply by using iodized salt, one can stay away from this deficiency.
Cancer Treatment
Radiation therapy is often used to destroy cancer cells. A beam of light emitted from a special machine is focused on the desired area for a specified amount of time to reduce tumor size and promote destruction of cancer cells. However, if the target site is in the neck area, it can interfere with thyroid gland function, eventually leading to hypothyroidism.
Thyroid Cancer Surgery
One of the side effects associated with thyroid cancer surgery is hypothyroidism. Removing the thyroid gland is what this surgery is about. This surgical procedure is referred to as thyroidectomy. With no thyroid gland in the neck area, the person is bound to get diagnosed with hypothyroidism post surgery.
Pituitary Disease
The pituitary gland is a circular shaped organ and its size is approximately equivalent to that of a pea. It is found at the base of the skull and one of its chief responsibilities is to ensure proper thyroid function. When the thyroid hormone level in the blood is less, it releases a specific hormone (TSH) that stimulates the thyroid gland to secrete more hormone. On the contrary, when the pituitary gland comes to know that the amount of thyroid hormone is significantly high in the bloodstream, it reduces the secretion of TSH hormone. This is how the pituitary gland works to control thyroid activity. However, if the pituitary gland is not working correctly, the person may either suffer from an overactive or underactive thyroid gland.
Postpartum Thyroiditis
The term postpartum thyroiditis typically describes a condition in which the thyroid gland becomes inflamed after pregnancy. This condition is relatively infrequent as only 5 to 10 out of 100 pregnant women suffer from postpartum thyroiditis. Although the inflammation does not cause any pain, it interferes with thyroid function. Post delivery, initially women get affected with hyperthyroidism. Once it subsides, the thyroid function returns to normal. Normal thyroid function gets disrupted with the onset of hypothyroidism after delivery. It is observed that women experience thyroid malfunction symptoms within a year's time post delivery.
Whatever may be the cause of hypothyroidism, underactive thyroid treatment consists of oral intake of drugs that contain synthetically prepared hormones. Levothroid is commonly prescribed that works to overcome thyroid hormone deficiency. The exact dosage will be decided after evaluating the TSH levels in the body. As hypothyroidism is the result of irreversible damage to the thyroid gland (not in case of postpartum thyroiditis), one may have to take this medication for lifetime.