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Thyroid and Hypothyroidism

  • The thyroid is a small, butterfly-shaped gland located in the neck. Thyroid hormones influence body temperature, heart rate, energy levels, weight management, and more.
  • Hypothyroidism is the most common thyroid condition in which an underactive thyroid gland doesn't produce enough thyroid hormones.
  • Symptoms include fatigue, weight gain, cold intolerance, dry skin, constipation, depression, and slowed heart rate.
  • The most common treatment is synthetic thyroid hormone replacement therapy (levothyroxine).

What is Thyroid?

The thyroid is a small, butterfly-shaped gland located at the front of the neck. It is part of the endocrine system, which is responsible for producing and releasing hormones that regulate various bodily functions. The thyroid gland produces and releases two main hormones: thyroxine (T4) and triiodothyronine (T3).

The thyroid gland's function is tightly regulated to maintain a balance of thyroid hormone levels in the body. Too much thyroid hormone production leads to a condition called hyperthyroidism, while too little hormone production results in hypothyroidism. These conditions can have significant impacts on metabolism, energy levels, growth, and overall health.

Role of Thyroid Hormones

The thyroid gland's function is tightly regulated to maintain a balance of thyroid hormone levels in the body. Too much thyroid hormone production leads to a condition called hyperthyroidism, while too little hormone production results in hypothyroidism. These conditions can have significant impacts on metabolism, energy levels, growth, and overall health.

Your thyroid plays a crucial role in many bodily functions, including the following:

  • Regulating metabolism: The thyroid hormones T3 and T4 control the rate at which cells convert oxygen and calories into energy. They affect nearly every organ system and influence processes such as growth, development, and temperature regulation.
  • Regulating body temperature: Thyroid hormones affect the production and release of heat generated by the body's cells, helping to maintain a stable body temperature.
  • Promoting growth and development: Thyroid hormones influence bone growth, brain development, and the maturation of various tissues and organs in children and adolescents.
  • Regulating heart rate and blood pressure: Thyroid hormones regulate the heart rate, the strength of heart contractions, and the relaxation of blood vessels. Imbalances in thyroid hormone levels can lead to cardiovascular issues such as changes in heart rate, high blood pressure, and cholesterol imbalances.
  • Controlling muscle and nerve function: Thyroid hormones are necessary for proper muscle and nerve function, including skin and bone maintenance.
  • Supporting reproductive health: Thyroid hormones are involved in menstrual cycles in women and sperm production in men. Imbalances in thyroid function can lead to menstrual irregularities, fertility issues, and complications during pregnancy.

Evaluating Thyroid Levels

Your thyroid function can be evaluated and its levels can be measured by a variety of blood tests. These exams, which are also known as thyroid function tests, used to diagnose thyroid problems:

  • Thyroid-stimulating hormone (TSH) test

    This is often the initial test used to assess thyroid function. TSH is produced by the pituitary gland and stimulates the thyroid gland to produce T3 and T4. Elevated TSH levels indicate an underactive thyroid (hypothyroidism), while low TSH levels indicate an overactive thyroid (hyperthyroidism).

  • Free T4 (FT4) test

    This test measures the level of unbound or free thyroxine (T4) hormone in the blood. FT4 represents the active form of T4 that is available for use by the body's tissues. Abnormal FT4 levels can help diagnose hypothyroidism or hyperthyroidism.

  • Total T4 (thyroxine) test

    This test measures the total amount of T4 in the blood, including both the free (unbound) and bound forms. It provides an overall measurement of T4 levels but does not distinguish between hypo- or hyperthyroidism as effectively as the FT4 test.

  • Free Triiodothyronine (FT3) Test

    This test measures the level of unbound or free triiodothyronine (T3) hormone in the blood. FT3 represents the active form of T3 that has the most physiological effects. It is often used in conjunction with other thyroid function tests to evaluate thyroid status more comprehensively.

  • Total T3 (triiodothyronine) test

    This test measure the total level of triiodothyronine (T3) hormone in the blood. Total T3 includes both the free (unbound) T3 and the T3 that is bound to proteins in the blood.

  • Thyroglobulin (Tg) test

    The Tg test measures the level of thyroglobulin, a protein produced by the thyroid gland. It is primarily used in monitoring thyroid cancer treatment and surveillance for recurrence or metastasis.

  • Thyroid antibody tests

    These tests are commonly used to determine the various autoimmune thyroid disorders.

Know Your Thyroid

The thyroid is a hormone-producing gland located at the lower front area of your neck. Its job is to take the iodine consumed in our diets and use it to create hormones that are subsequently released into our bloodstream.

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Hypothyroidism or underactive thyroid disease is the most common thyroid condition in which your thyroid gland doesn't produce enough thyroid hormones.

The thyroid hormones regulate many bodily functions like metabolism, heart rate, body temperature, and energy levels. In hypothyroidism, your thyroid gland doesn't produce enough of these hormones, which can lead to symptoms such as fatigue, weight gain, constipation, dry skin, hair loss, and sensitivity to cold.


Hypothyroidism is a relatively common condition, especially among women and older adults.

According to the American Thyroid Association, it’s estimated that around 5-10% of Americans have some form of hypothyroidism, with women being about 5 to 8 times more likely to develop the condition than men.

The prevalence of hypothyroidism also increases with age, and it’s estimated that up to 20% of women over the age of 60 may have this condition.

Signs and Symptoms

Hypothyroidism can cause a variety of signs and symptoms that can vary in severity and may develop gradually over time.

Common signs and symptoms include the following:

  • Cold temperature intolerance and/or sensitivity
  • Dry, coarse skin and/or hair
  • Extreme fatigue
  • Muscle cramps, weakness, and/or soreness
  • Voice change and become lower or hoarser
  • Constipation
  • Weight gain or having trouble losing weight
  • Myalgias or muscle pain
  • Weakness
  • Depression
  • Bradycardia (slow heart rate)
  • Hair loss
  • Menorrhagia (heavier than normal menstrual periods)
  • Memory and mental impairment (“brain fog”)

In more severe cases, hypothyroidism can cause additional symptoms, including:

  • Puffy face, hands, and/or feet
  • Goiter (enlarged thyroid gland)
  • Decreased sense of taste and smell
  • Shortness of breath

Some individuals with hypothyroidism may not experience any noticeable symptoms, or their symptoms may be mild and easily dismissed as part of the normal aging process. That’s why regular screening and monitoring of your thyroid function can help identify and manage this condition early, even before symptoms develop.

Hypothyroidism and Impotence

Hypothyroidism that is left untreated occasionally has been linked to erectile dysfunction. Low testosterone levels are possible when a pituitary gland problem is the root cause of your hypothyroidism.

If erectile dysfunction was a direct result of this hormonal imbalance, then the treatment of hypothyroidism will improve this problem.


Hypothyroidism can be caused by a variety of factors, including:

  • Autoimmune disease: Hashimoto's thyroiditis, also commonly referred to as Hashimoto’s disease, is the most common cause of hypothyroidism. It’a an autoimmune disorder in which your body's immune system attacks your thyroid gland, leading to inflammation and damage that can impair thyroid hormone production.
  • Radiation therapy: Radiation therapy to your neck or head for cancer treatment or other conditions can damage your thyroid gland and impair its function, leading to hypothyroidism.
  • Surgical removal of the thyroid gland: If your thyroid gland is surgically removed due to cancer, nodules, or other conditions, you will need to take thyroid hormone replacement therapy for life to replace the hormones that your thyroid gland would have produced.
  • Certain medications: Some medications, such as lithium and amiodarone, can interfere with thyroid hormone production and lead to hypothyroidism.
  • Iodine deficiency: Iodine is an essential nutrient that your body needs to produce thyroid hormones. A lack of iodine in your diet can lead to hypothyroidism.
  • Congenital hypothyroidism: Some infants are born with an underactive thyroid gland, which can be due to genetic factors, a problem with thyroid gland development, or maternal iodine deficiency during pregnancy.

To be diagnosed with rheumatoid arthritis, you must meet certain criteria established by the American College of Rheumatology. These criteria take into account the number and location of affected joints, blood test results, and other clinical factors.

A rheumatologist, or a doctor who specializes in the treatment of rheumatic diseases, will typically make the diagnosis and develop a treatment plan for you.

Myxedema—Severe Hypothyroidism

Myxedema is a severe case of hypothyroidism with extremely low levels of thyroid hormones in the body. Myxedema is relatively rare but can occur in individuals with long-standing, untreated, or poorly managed hypothyroidism.

Here are some characteristics and manifestations of a severe case of hypothyroidism:

  • Extreme fatigue and weakness, to the point of being bedridden or unable to carry out daily activities.
  • Mental confusion, disorientation, and even coma can occur. This is especially seen in myxedema coma, which is a medical emergency.
  • Hypothermia: Low body temperature, often below normal ranges, leading to cold intolerance and an inability to regulate body temperature.
  • A significantly slowed heart rate, resulting in reduced cardiac output and circulation.
  • Shallow and slow breathing, respiratory depression, and potentially respiratory failure in severe cases.
  • Swelling and puffiness particularly around the face, lips, and tongue.
  • Skin becomes dry, rough, and lacking elasticity. It may appear pale and cool to the touch.
  • Vocal changes, including hoarseness and difficulty speaking due to muscle weakness and swelling around the vocal cords.
  • Constipation, bloating, and reduced appetite can occur.

Severe hypothyroidism requires immediate medical attention and hospitalization. Myxedema coma is a life-threatening condition associated with multiorgan dysfunction, low blood pressure, and altered mental status. Treatment involves administration of intravenous thyroid hormone replacement therapy, primarily with synthetic thyroxine (T4), along with supportive care to address complications, stabilize vital signs, and restore electrolyte balance.

Levothyroxine To Treat Low Thyroid (Hypothyroidism)

The drug of choice for hypothyroidism is levothyroxine (T4). Levothyroxine is a synthetic (man-made) version of the thyroxine hormone. It replaces thyroxine when your thyroid gland cannot produce it and prevents hypothyroidism symptoms.

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Treatment Options

Hormone replacement therapy

The goal of HRT is to restore normal levels of thyroid hormone in the body. Some medications that could be used to treat hypothyroidism include the following:


The drug of choice for hypothyroidism is levothyroxine (T4). Levothyroxine (brand: Synthroid) is a synthetic or man-made version of the thyroxine hormone. This medication is used to replace thyroxine when your thyroid gland cannot produce it and prevents hypothyroidism symptoms.

  • This medication is taken by mouth, once a day with water, at least 60 minutes before breakfast or at bedtime (at least 3 hours after your last meal).
  • Common side effects: fast or irregular heartbeats, shortness of breath, fever, hot flashes, sweating, chest pain, pain spreading to your jaw or shoulders, weight loss, irritability, feeling hot/sweating, tremors, feeling nervous and/or irritable

Armour Thyroid (generic: Desiccated thyroid)

This medication contains both T3 (triiodothyronine) and T4 (thyroxine) hormones in a ratio that is similar to what is found in the human body.

  • Unlike synthetic thyroid hormone medications, Armour Thyroid is a natural thyroid hormone replacement therapy that is derived from porcine (pig) thyroid glands.
  • Common side effects: fast heartbeats, changes in the mood, difficulty sleeping. nervousness or irritability, fatigue, weight loss

Liothyronine (generic: Cytomel)

Liothyronine is a prescription medication that’s a synthetic version of the thyroid hormone triiodothyronine (T3).

  • Liothyronine is usually prescribed for individuals who have not responded well to treatment with levothyroxine. Unlike levothyroxine, which is converted to T3 in your body, Liothyronine is a direct source of T3.
  • Common side effects: fast or irregular heartbeats, hair loss, difficulty sleeping, fever, shakiness, weak muscles, fatigue, weight loss

Diet and lifestyle changes

Eating a balanced diet, getting regular exercise, and managing stress can help manage symptoms of hypothyroidism.

Alternative therapies

Some individuals with hypothyroidism find relief from alternative therapies such as acupuncture, herbal supplements, and meditation. However, these treatments should be used in conjunction with traditional medical treatment and under the guidance of a healthcare provider.


In rare cases, surgery may be necessary to remove a large goiter or thyroid nodules that are causing symptoms of hypothyroidism.

Other Thyroid Conditions

While hypothyroidism is the most common thyroid condition, it's worth noting that thyroid disorders encompass a range of conditions, and the most common thyroid problem can vary depending on the population being studied.

Other common thyroid problems include:

  • Hyperthyroidism

    Hyperthyroidism, often caused by Graves' disease, is characterized by excessive production of thyroid hormones. It is less common than hypothyroidism but still prevalent, affecting approximately 1% to 2% of the population.

    Symptoms may include weight loss, increased appetite, heat intolerance, sweating, rapid heartbeat, anxiety, tremors, and difficulty sleeping.

  • Thyroid nodules

    Thyroid nodules are abnormal growths or lumps that form within the thyroid gland. They can be either benign or cancerous. Thyroid nodules are quite common, with estimates suggesting that up to 50% of individuals may have a thyroid nodule at some point in their lives. The majority of nodules are benign, and only a small percentage are cancerous.

  • Thyroiditis

    Thyroiditis refers to inflammation of the thyroid gland. It can be caused by infections, autoimmune conditions, or other factors.

    Depending on the type of thyroiditis, symptoms may include pain in the thyroid area, enlargement of the thyroid gland, and temporary hyperthyroidism followed by hypothyroidism.

  • Thyroid cancer

    Thyroid cancer is relatively rare compared to other cancers but has seen an increase in incidence over recent years. It is more prevalent in women than men. The most common types of thyroid cancer include papillary carcinoma, follicular carcinoma, and medullary carcinoma.

    Symptoms may include a palpable lump in the neck, hoarseness, difficulty swallowing, enlarged lymph nodes, and in some cases, voice changes.

  • Thyroid Eye Disease

    Also known as Graves' ophthalmopathy or thyroid-associated ophthalmopathy, this condition is typically associated with Graves' disease.

    It causes inflammation and swelling of the tissues around the eyes, leading to bulging eyes, dryness, redness, double vision, and eye irritation.