Underactive thyroid or hypothyroidism is a condition in which the thyroid gland is unable to produce enough thyroid hormone. This affects the bodily functions, mainly metabolism or the way your body uses energy and results in various undesirable symptoms. It is important to know what causes your thyroid to be underactive or the factors that cause hypothyroidism to be able to manage the condition well.

An underactive thyroid can affect the process of metabolism, growth, mood and other functions causing great disturbances. Hypothyroidism can result in weight gain, constipation, sleeplessness and increased irritability. While some factors can cause your thyroid to be underactive, some are a result of treatment of other conditions including hyperthyroidism, which is increased production of thyroid hormone.

What Causes Your Thyroid to be Underactive (Hypothyroidism)?

What Causes Your Thyroid to be Underactive (Hypothyroidism)?

Underactive thyroid or Hypothyroidism is a condition in which certain factors can cause slowing down of metabolism and body functions. A number of different factors can cause the thyroid gland to show reduced activity, and go down on the production of the thyroid hormone. It is worth understanding as to what causes your thyroid to be underactive.

The following are some possible causes for your thyroid to be underactive or hypothyroidism:

  • Congenital Hypothyroidism: Some people are born with underdeveloped or dysfunctional thyroid glands, in which case, their thyroid glands are not able to produce enough thyroid hormone. This may be noticed since childhood and usually affects their physical and mental growth.
  • Thyroiditis: Thyroiditis or 'Hashimoto's Thyroiditis', is an 'autoimmune' disorder, which refers to an inflammation of the thyroid gland. In this, the body begins producing antibodies which attack and destroy the thyroid gland. Viral infections or presence of autoimmune conditions can often cause thyroiditis, which can cause your thyroid to be underactive.
  • Radiation Therapy: Radiation therapy over the neck area can damage the cells of thyroid gland and cause your thyroid to be underactive (hypothyroidism). Radiation therapy is used to treat cancers like lymphoma. Effects of radiation to the neck make it difficult for the thyroid gland to produce the hormone, which is an important cause for your thyroid to be underactive (hypothyroidism).
  • Radioactive Iodine Treatment: The radioactive iodine treatment is commonly prescribed to people with overactive thyroid glands in hyperthyroidism. The radiation destroys the cells of the thyroid glands, and can cause your thyroid to be underactive (hypothyroidism). This is another important cause for your thyroid to be underactive. Proper management of hyperthyroidism can help to regulate thyroid function.
  • Medication: Certain medications used for the treatment of various disorders like psychiatric conditions, heart problems, and cancer carry the potential to affect the thyroid function. This can cause your thyroid to be underactive and result in symptoms of hypothyroidism. Considering proper treatment and changing certain medications can help to manage the condition better.
  • Thyroid Surgery: It can sometimes become necessary to remove the thyroid gland with surgery, which can cause an underactive thyroid or hypothyroidism. However, if only a certain part of the gland is removed in the procedure, it still may be able to produce enough hormone to meet the body's requirement. Appropriate treatment and replacement may have to be considered as important ways to manage this condition.
  • Iodine Deficiency: Your body cannot produce iodine and it is necessary for proper thyroid function. Iodized table salt is rich in iodine and other food items like shellfish, eggs, saltwater fish, seaweed, and others are great sources of it. Deficiency of iodine in your body can be a major cause your thyroid to be underactive (hypothyroidism) as well as a host of other health problems. Iodine deficiency is one of the commonest factors that can cause your thyroid to be underactive.
  • Pregnancy: The thyroid gland can sometimes become inflamed during the pregnancy of the individual. The condition is referred to as postpartum thyroiditis. This condition usually involves a significant increase in thyroid hormone levels, which is then followed by a drop, or hypothyroidism. The changes occurring during pregnancy and hormonal imbalances may be contributing factors that can cause your thyroid to be underactive. Managing pregnancy with a balanced diet, regular activity and stress free environment can help to maintain thyroid function.
  • Pituitary Gland Disorders: Various disorders of the pituitary gland or damage to it can also cause your thyroid to be underactive (hypothyroidism). The pituitary gland is responsible for stimulating the thyroid gland and telling it how much of the hormone it needs to release by secreting the 'thyroid stimulating hormone' or TSH. If it fails to, so does the thyroid gland. Thus, if the pituitary gland is affected, it also affect thyroid function and cause your thyroid to be underactive.

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Written, Edited or Reviewed By:


Last Modified On: May 31, 2017

Pain Assist Inc.

Pramod Kerkar
  Note: Information provided is not a substitute for physician, hospital or any form of medical care. Examination and Investigation is necessary for correct diagnosis.

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