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Hypothyroidism: Underactive Thyroid Gland - Signs, Symptoms, Causes and Treatment

  • Publish Date : 2014/11/09 - (Rev. 2017/01/30)
  • Author : Thomas C. Weiss
  • Contact : Disabled World


Information regarding Hypothyroidism, a condition caused when the thyroid gland does not produce enough of certain important hormones.

Main Document

'Hypothyroidism,' or under-active thyroid, is a condition in which a person's thyroid gland does not produce enough of certain important hormones. Women, particularly women over the age of 60, are more likely to experience hyperthyroidism. Hypothyroidism upsets the usual balance of chemical reactions in a person's body. It rarely causes symptoms in the early stages, although over time untreated hypothyroidism may cause several health issues such as joint pain, obesity, heart disease and infertility. Accurate thyroid function tests are available to diagnose hypothyroidism and treatment of it with synthetic thyroid hormone is usually simple, effective and safe after a person and their doctor find the right dose.

Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone. This condition is often called under-active thyroid. Hypothyroidism upsets the normal balance of chemical reactions in your body. The thyroid gland is located in the front lower part of your neck. Hormones released by the gland travel through your bloodstream and affect nearly every part of your body, from your heart and brain, to your muscles and skin. Too little iodine in the diet is the most common cause of hypothyroidism. Women, especially those older than age 60, are more likely to have hypothyroidism.

Difference Between Hypothyroidism and Hyperthyroidism:

  • Hypothyroidism - Occurs when the gland is underactive, and can present itself at any age, but the risk increases as you get older, and it is most commonly triggered by genetics. Females are three times more likely than men to develop hypothyroidism. Hypothyroidism causes symptoms such as slowed metabolism, tiredness, and weight gain. Having an underactive thyroid can decrease or slow down your bodily functions.
  • Hyperthyroidism - Hyperthyroidism is the opposite of hypothyroidism. It occurs when the thyroid is overactive, producing too much thyroid hormone. With hyperthyroidism, you may find yourself with more energy, as opposed to less. You may experience weight loss as opposed to weight gain. And you may feel anxious as opposed to depressed.

Symptoms of Hypothyroidism

The signs and symptoms of hypothyroidism vary depending upon the severity of the person's hormone deficiency. In general, any issues a person experiences tend to develop slowly and over several years. At first, a person might barely notice the symptoms of hypothyroidism, such as weight gain or fatigue, or they might simply attribute them to aging. Yet as the person's metabolism continues to slow, they may develop more obvious signs and symptoms. The signs and symptoms of hypothyroidism can include:

  • Fatigue
  • Dry skin
  • Puffy face
  • Depression
  • Hoarseness
  • Constipation
  • Thinning hair
  • Muscle weakness
  • Slower heart rate
  • Impaired memory
  • Unexplained weight gain
  • Elevated blood cholesterol
  • Increased sensitivity to cold
  • Pain, swelling, or stiffness in the joints
  • Muscle aches, stiffness and tenderness
  • Heavier than usual or irregular menstrual periods

People with untreated hypothyroidism can experience signs and symptoms that gradually become more severe. Constant stimulation of the person's thyroid gland to release more hormones might lead to an enlarged thyroid or, 'goiter.' The person may become more forgetful, their thought processes may slow down, or they may feel depressed. Advanced hypothyroidism is known as, 'myxedema,' and is rare, although when it occurs it may be life-threatening. Signs and symptoms of myxedema include decreased breathing, low blood pressure, decreased body temperature, unresponsiveness and coma. In extreme instances myxedema may be fatal.

Hypothyroidism and Infants

While hypothyroidism most often affects women who are middle-aged or older, anyone may develop the condition, to include infants. Initially, babies born without a thyroid gland, or with a gland that does not work appropriately, might have fewer signs and symptoms. When newborns do experience issues with hypothyroidism they can include the following:

  • Constipation
  • Frequent choking
  • Poor muscle tone
  • Excessive sleepiness
  • A large protruding tongue
  • A puffy appearance to their face

An infant with hypothyroidism may experience yellowing of their skin and the whites of their eyes. In most instances, this occurs when a baby's liver cannot metabolize a substance called, 'bilirubin,' which usually forms when the body recycles old or damaged red blood cells. When hypothyroidism in infants is not treated, even mild instances may lead to severe physical and mental disabilities.

Generally, children and teenagers who develop hypothyroidism experience the same signs and symptoms adults do. They might also experience the following:

  • Delayed puberty
  • Poor mental development
  • Poor growth resulting in short stature
  • Delayed development of permanent teeth

Causes of Hypothyroidism

When a person's thyroid does not produce enough hormones, the balance of chemical reactions in their body may be upset. There can be a number of causes, to include autoimmune disease, radiation therapy, treatment for hypothyroidism, certain medications and thyroid surgery.

The thyroid is a small and butterfly-shaped gland situated at the base of the front of a person's neck, just below their Adam's apple. Hormones produced by the thyroid gland, 'Triiodothyronine (T3),' and, 'Thyroxine (T4),' have a tremendous impact on a person's health, affecting every aspect of their metabolism. They maintain the rate at which a person's body uses fats and carbohydrates, helping to control a person's body temperature, influencing a person's heart rate, as well as assisting with regulation of the production of proteins.

Hypothyroidism results when a person's thyroid gland fails to produce enough hormones. Hypothyroidism may be due to several factors, to include the following:

  • Radiation Therapy:

    Radiation used to treat cancers of a person's head and neck may affect their thyroid gland and might lead to hypothyroidism.

  • Medications:

    Several medications can contribute to hypothyroidism. One of these medications is lithium, a medication used to treat certain forms of psychiatric disorders.

  • Pituitary Disorder:

    A fairly rare cause of hypothyroidism is the failure of the pituitary gland to produce enough thyroid-stimulating hormone, usually because of a benign tumor of the person's pituitary gland.

  • Thyroid Surgery:

    Removal of all, or a large portion of, a person's thyroid gland may diminish or even stop hormone production. In this instance, a person will need to take thyroid hormone for the remainder of their life.

  • Iodine Deficiency:

    The trace mineral iodine, found mainly in seaweed, seafood, plants grown in iodine-rich soil and iodized salt, is essential for the production of thyroid hormones. In some parts of the world, iodine deficiency is common - yet the addition of iodine to table salt has nearly eliminated this issue in America. Conversely, taking in too much iodine may cause hypothyroidism.

  • Congenital Disease:

    Some babies are born with a defective thyroid gland, or no thyroid gland at all. In most instances, the thyroid gland did not develop as it should have for unknown reasons, yet some children have an inherited form of the disorder. Often times, infants with congenital hypothyroidism appear fine at birth. Most states now require newborns to go through thyroid screening because of this fact.

  • Autoimmune Disease:

    People who develop a particular inflammatory disorder known as, 'Hashimoto's thyroiditis,' have the most common cause of hypothyroidism. Autoimmune disorders occur when a person's immune system produces antibodies that attack their own tissues. At times this process involves the person's thyroid gland. Scientists are not sure why a person's body produces antibodies against itself. Some think a bacterium or virus may trigger the response, while others think a genetic flaw might be involved. Autoimmune diseases most likely result from more than a single factor. Yet however it occurs, these antibodies affect the thyroid's ability to produce hormones.

Risk Factors for Hypothyroidism

While anyone may develop hypothyroidism, a person is at increased risk if they are a woman over the age of 60, have autoimmune disease, or have a close relative such as a parent or grandparent with an autoimmune disease. Additional risk factors for hypothyroidism include having:

  • Had thyroid surgery
  • Received radiation to the neck or upper chest
  • Been pregnant, or delivered a baby, within the prior 6 months
  • Been treated with radioactive iodine, or anti-thyroid medications

Complications of Hypothyroidism

Untreated hypothyroidism may lead to several health issues such as goiter, heart problems, mental health issues, peripheral neuropathy, myxedema, infertility or birth defects. What follows are descriptions of these potential complications.

  • Mental Health Issues:

    Depression may occur early in hypothyroidism and might become more severe over time. Hypothyroidism may also cause slowed mental functioning.

  • Infertility:

    Low levels of thyroid hormone may interfere with ovulation, which impairs fertility. Some of the causes of hypothyroidism, such as autoimmune disorder, also impair fertility. Treating hypothyroidism with thyroid hormone replacement therapy may not completely restore fertility. Additional interventions may be required as well.

  • Goiter:

    Constant stimulation of a person's thyroid to release more hormones might cause their thyroid gland to become larger, a condition known as, 'goiter.' Hashimoto thyroiditis is one of the most common causes of a goiter. While usually not uncomfortable, a large goiter can affect a person's appearance and might interfere with swallowing or breathing.

  • Myxedema:

    Myxedema is a rare and life-threatening condition and is the result of long-term, undiagnosed hypothyroidism. Its signs and symptoms include drowsiness and intense cold intolerance, followed by profound lethargy and unconsciousness. A myxedema coma might be triggered by sedatives, infection, or other stress on a person's body.

  • Peripheral Neuropathy:

    Long-term, uncontrolled hypothyroidism can cause damage to a person's peripheral nerves, the nerves that carry information from a person's brain and spinal cord to the rest of their body. Signs and symptoms of peripheral neuropathy may include numbness, pain and tingling in the areas affected by the nerve damage. It might also cause muscle weakness, or loss of muscle control.

  • Birth Defects:

    Babies born to women with untreated thyroid disease might have an increased risk of birth defects than babies born to mothers who are healthy. These children are also more prone to serious intellectual and developmental issues. Infants with untreated hypothyroidism present at birth are at risk of serious issues with both physical and mental development. Yet if the condition is diagnosed within the first few months of a person's life, the chances of average development are good.

Tests and Diagnosis for Hypothyroidism

Due to the fact that hypothyroidism is more prevalent in older women, some doctors recommend that older women be screened for the disorder during routine annual physical exams. Some doctors also recommend that pregnant women, or women thinking of becoming pregnant, be tested for hypothyroidism. Generally, your doctor might test for under-active thyroid if you are feeling increasingly tired, have dry skin, weight gain or constipation, or if you have prior thyroid issues or goiter.

A diagnosis of hypothyroidism is based upon a person's symptoms and the results of blood tests that measure the level of TSH and at times the level of the thyroid hormone, 'thyroxine.' A low level of thyroxine and high level of TSH indicate an under-active thyroid. The reason is because a person's pituitary produces more TSH in an effort to stimulate their thyroid gland into producing more thyroid hormone.

In the past, doctors were not able to detect hypothyroidism until symptoms were fairly advanced. Yet by using the sensitive TSH test, doctors are able to diagnose thyroid disorders far earlier, often times before a person experiences symptoms. Due to the fact that the TSH test is the best screening test, a person's doctor will most likely check TSH first and follow up with a thyroid hormone test if needed. TSH tests also play an important role in the management of hypothyroidism. The tests help a person's doctor to determine the appropriate dosage of medication, both at the start and over time. In addition, TSH tests are used to help diagnose a condition called subclinical hypothyroidism, which usually causes no outward signs or symptoms. In this condition, you have normal blood levels of triiodothyronine and thyroxine, but higher than normal levels of TSH. In this condition, a person has average blood levels of, 'triiodothyronine,' and, 'thyroxine,' yet higher than average levels of TSH.

Treatment and Medications

The standard treatment for hypothyroidism involves the daily use of the synthetic thyroid hormone, 'levothyroxine.' The oral medication restores adequate hormone levels, reversing the signs and symptoms of hypothyroidism. One to two weeks after a person begins treatment they will notice that they are feeling less fatigued. The medication also gradually lowers a person's cholesterol levels elevated by the disease and might reverse any weight gain. Treatment with levothyroxine is usually a life-long effort, but because the dosage a person needs may change their doctor is likely to check their TSH level each year.

Determining the proper dosage might take time. To determine the appropriate dosage of levothyroxine at the start, a person's doctor usually checks the person's level of TSH after 2-3 months. Excessive amounts of the hormone may cause side-effects which include:

  • Insomnia
  • Shakiness
  • Heart palpitations
  • Increased appetite

If a person has coronary artery disease or severe hypothyroidism, their doctor might begin treatment with a smaller amount of medication and gradually increase their dosage. Progressive hormone replacement permits the person's heart to adjust to the increase in metabolism.

Levothyroxine causes almost no side-effects when used in the proper dose and is fairly inexpensive. If a person changes brands, it is important for them to let their doctor know to ensure they are still receiving the correct dosage. It is also important for them not to skip any doses, or to stop taking the medication because they are feeling better. Stopping the medication means their symptoms will gradually return.

Certain medications, supplements, as well as some foods might affect a person's ability to absorb levothyroxine. It is important to communicate with your doctor if you eat large amounts of soy products, or a high-fiber diet, or if you take medications such as:

  • Cholestyramine
  • Iron supplements
  • Calcium supplements

Quick Facts:

  • Screening for hypothyroidism is performed in the newborn period in many countries, generally using TSH.
  • During pregnancy, the thyroid gland must produce 50% more thyroid hormone to provide enough thyroid hormone for the developing fetus and the expectant mother.
  • Hypothyroidism can be treated with manufactured levothyroxine; the dose is adjusted according to symptoms and normalization of the thyroxine and TSH levels.
  • Hypothyroidism may be prevented in a population by adding iodine to commonly used foods.

How to Perform a Thyroid Neck Exam

  • Use a mirror and focus on the lower middle area of your neck, above the collarbones, and below the Adam's apple (larynx). Your thyroid gland is located in this area of your neck.
  • While focusing on this area in the mirror, tip your head back.
  • Take a drink of water and swallow.
  • As you swallow, look at your neck. Check for any bulges or protrusions in this area when you swallow. Reminder: Don't confuse the Adam's apple with the thyroid gland. The thyroid gland is located further down on your neck, closer to the collarbone. You may want to repeat this process several times.
  • If you do see any bulges or protrusions in this area, see your physician. You may have an enlarged thyroid gland or a thyroid nodule and should be checked to determine whether cancer is present or if treatment for thyroid disease is needed.


  • Most hypothyroidism is primary in nature. Central/secondary hypothyroidism affects 1:20,000 to 1:80,000 of the population, or about one out of every thousand people with hypothyroidism.
  • In population-based studies, women were seven times more likely than men to have TSH levels above 10 mU/l.
  • Worldwide about one billion people are estimated to be iodine deficient; however, it is unknown how often this results in hypothyroidism.

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