Thyroid Health 101: What Causes Hypothyroidism?

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Thyroid Health 101: What Causes Hypothyroidism?

The thyroid gland is a butterfly-shaped endocrine gland that is normally located in the lower front of the neck. The gland produces hormones which are crucial in regulating many bodily functions, including basic metabolism. Thyroid function is also greatly influenced by the status of the adrenal glands. Thyroid disease is very broadly classified into two types. Hypothyroidism results from too little circulating thyroid hormones and is characterized by fatigue, weight gain, constipation, depression, hair loss, and mental or memory impairment.

Hypothyroidism

Hypothyroidism results from too little circulating thyroid hormones and is characterized by fatigue, weight gain, constipation, depression, hair loss, and mental or memory impairment.

Hypothyroidism can’t be cured. But in almost every patient, hypothyroidism can be completely controlled. It is treated by replacing the amount of hormone that your own thyroid can no longer make, to bring your T4 and TSH back to normal levels. So even if your thyroid gland can’t work right, T4 replacement can restore your body’s thyroid hormone levels and your body’s function. Synthetic thyroxine pills contain hormone exactly like the T4 that the thyroid gland itself makes. All hypothyroid patients except those with severe myxedema (life-threatening hypothyroidism) can be treated as outpatients, not having to be admitted to the hospital.

What Causes Hypothyroidism?

There can be many reasons why the cells in the thyroid gland can’t make enough thyroid hormone. Here are the major causes, from the most to the least common.

  • Autoimmune disease. In some people’s bodies, the immune system that protects the body from invading infections can mistake thyroid gland cells and their enzymes for invaders and can attack them. Then there aren’t enough thyroid cells and enzymes left to make enough thyroid hormone. This is more common in women than men. Autoimmune thyroiditis can begin suddenly or it can develop slowly over years. The most common forms are Hashimoto’s thyroiditis and atrophic thyroiditis.
  • Surgical removal of part or all of the thyroid gland. Some people with thyroid nodules, thyroid cancer, or Graves’ disease need to have part or all of their thyroid removed. If the whole thyroid is removed, people will definitely become hypothyroid. If part of the gland is left, it may be able to make enough thyroid hormone to keep blood levels normal.
  • Radiation treatment. Some people with Graves’ disease, nodular goiter, or thyroid cancer are treated with radioactive iodine (I-131) for the purpose of destroying their thyroid gland. Patients with Hodgkin’s disease, lymphoma, or cancers of the head or neck are treated with radiation. All these patients can lose part or all of their thyroid function.
  • Congenital hypothyroidism (hypothyroidism that a baby is born with). A few babies are born without a thyroid or with only a partly formed one. A few have part or all of their thyroid in the wrong place (ectopic thyroid). In some babies, the thyroid cells or their enzymes don’t work right.
  • Thyroiditis. Thyroiditis is an inflammation of the thyroid gland, usually caused by an autoimmune attack or by a viral infection. Thyroiditis can make the thyroid dump its whole supply of stored thyroid hormone into the blood at once, causing brief hyperthyroidism (too much thyroid activity); then the thyroid becomes underactive.
  • Medicines. Medicines such as amiodarone, lithium, interferon alpha, and interleukin-2 can prevent the thyroid gland from being able to make hormone normally. These drugs are most likely to trigger hypothyroidism in patients who have a genetic tendency to autoimmune thyroid disease.
  • Too much or too little iodine.The thyroid gland must have iodine to make thyroid hormone. Iodine comes into the body in food and travels through the blood to the thyroid. Keeping thyroid hormone production in balance requires the right amount of iodine. Taking in too much iodine can cause or worsen hypothyroidism.
  • Damage to the pituitary gland.The pituitary, the “master gland,” tells the thyroid how much hormone to make. When the pituitary is damaged by a tumor, radiation, or surgery, it may no longer be able to give the thyroid instructions, and the thyroid may stop making enough hormone.
  • Rare disorders that infiltrate the thyroid. In a few people, diseases deposit abnormal substances in the thyroid and impair its ability to function. For example, amyloidosis can deposit amyloid protein, sarcoidosis can deposit granulomas, and hemochromatosis can deposit iron.

Treatment

Hypothyroidism can’t be cured. But in almost every patient, hypothyroidism can be completely controlled. It is treated by replacing the amount of hormone that your own thyroid can no longer make, to bring your T4 and TSH levels back to normal levels. So even if your thyroid gland can’t work right, T4 replacement can restore your body’s thyroid hormone levels and your body’s function.

TSH (Thyroid Stimulating Hormone)

TSH Is a hormone produced by the pituitary gland and whose function is to signal the thyroid gland to make more thyroid hormone. It represents the pituitary’s need or desire for more or less thyroid hormone. An optimal value of TSH means the thyroid hormone levels match the body’s energy needs and/or ability to utilize the energy.

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It is important to recognize that the normal range given on your lab report is very wide. For your test result to be out of range indicates a large change has occurred. Although still considered normal, a test result very high or low within the normal range is still indicative of a large change. The Free T3 and the Free T4 thyroid tests are recommended as follow-up tests.

Finally…

Better health is critical to happiness and well-being. It also makes an important contribution to your job, as healthy people have been proven to live longer and are more productive. All of your organs have an important role to play in making you the healthiest and happiest version of yourself.

No matter how old a person is or what kind of diet and exercise pattern he or she follows, it’s possible to make adjustments and improve their health. Contact us for questions or to schedule an appointment. 

(Some information provided by the American Thyroid Association).

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