About the Thyroid and Thyroid Disease

Thyroid Disease

The normal thyroid is a small gland weighing about an ounce that sits behind the Adam’s apple in the lower part of the neck, in front of the windpipe.

It derives its name from the Greek word thyreoeides, meaning “shield-shaped.” In fact, it looks like a bowtie or butterfly, with the two “wings,” or lobes, of the gland connected in the middle by the isthmus.

The thyroid, like other glands, is a discrete soft body made up of a large number of vessels that produce, store, and release - or secrete - some substance. Some glands secrete their products outside the body, some inside. Those that secrete hormones and metabolic substances on the inside of the body are known as endocrine glands. The endocrine glands include the thyroid, the parathyroids, the adrenal gland, the pancreas, the pituitary gland, the pineal gland, the gonads (ovaries and testes), and the thymus.

Doctors who specialize in treating patients with endocrine problems - disorders of the endocrine glands - are called endocrinologists.

Hormones are internal secretions carried in the blood to various organs. The thyroid’s main purpose is to produce, store, and release two key hormones: triiodothyronine, also called T3; and thyroxine, or T4. The numbers 3 and 4 refer to the number of iodine molecules attached to each hormone.

Thyroid cells are the primary cells in the body capable of absorbing iodine, an essential nutrient. The thyroid takes in iodine, obtained through food, iodized salt, or supplements, and combines that iodine with the amino acid tyrosine, converting them to T3 and T4.

A healthy thyroid produces about 20 percent T3 and 80 percent T4. T3 is the biologically active hormone that is used by the cells; it is several times stronger than T4. As needed, the body converts the inactive T4 to active T3 by removing one iodine molecule. This conversion process is called monodeiodination. This conversion can take place in certain organs other than the thyroid, including the hypothalamus, a part of your brain.

T3 and T4 both exist in two forms: unbound and bound. Unbound, or free, T3 or T4 are biologically active; bound T3 and T4 are attached to the thyroid-binding globulin (TBG) protein. When measured in the blood, the free, or unbound, T3 and T4 levels tend to be most representative of the actual hormone available for use by the body.

The role of your thyroid hormones is to control your metabolism - the process by which oxygen and calories are converted to energy for use by your cells and organs. There’s not a single cell in your body that doesn’t depend on thyroid hormone for regulation and for energy in some form. And the thyroid hormones have a number of functions as they travel through the bloodstream.

* They enable cells to convert oxygen and calories into energy

* Help the body process carbohydrates

* Aid in the proper functioning of muscles

* Enable proper sexual development and functioning

* Help the heart pump properly and effectively

* Help the body to breathe normally

* Help the intestinal system digest and eliminate food

* Strengthen hair, nails, and skin Help the brain to function properly Help with normal bone growth

* Now that you have some idea of what the thyroid is and its location and function, let’s go into more detail about how it fits into the overall functioning of the body.

The Thyroid Gland: Setting the Pace

When your thyroid works normally, it produces and secretes the amount of T3 and T4 necessary to keep various body functions moving at their proper pace. However, the thyroid does not do this alone. It works as part of a bigger system, one that includes the pituitary gland and the hypothalamus.

Here’s how the system works. The hypothalamus constantly monitors the pace of many of the body’s functions. It also monitors and reacts to a number of other factors, including environmental factors such as heat, cold, and stress. If the hypothalamus senses that certain adjustments are needed to react to any of these factors, then it produces thyrotropin-releasing hormone, known as TRH.

TRH is sent from the hypothalamus to the pituitary gland. The pituitary gland is stimulated to produce a substance called thyrotropin, but better known as thyroid-stimulating hormone, or TSH for short. The pituitary gland also monitors the body and can release TSH based on the thyroid hormone levels circulating in your blood.

TSH is sent to the thyroid gland, where it causes the thyroid to produce, store, and release more T3 and T4 thyroid hormones.

The released thyroid hormones move into the bloodstream, carried by a plasma protein known as thyroxine-binding globulin (TBG).

Now in the bloodstream, the thyroid hormone travels throughout the body, carrying orders to the various organs. Upon arriving at a particular tissue in the body, thyroid hormones interact with receptors located inside the nucleus of the cells. Interaction of the hormone and the receptor will trigger a certain function, giving directions to that tissue regarding the rate at which it should operate.

When the hypothalamus senses that the need for increased thyroid hormone production has ended, it reduces production of TRH. The reduced production of TRH in turn causes the pituitary to decrease production of TSH, and the reduced TSH levels send the message to the gland itself to slow production of thyroid hormone. By this system, many of the body’s organs keep working at the proper pace.

Think of the entire feedback loop as somewhat like the thermostat in your house. It’s set to maintain a particular temperature, and when it detects that your house has become too hot, it signals to either stop blowing heat (or start blowing air conditioning). And when the house becomes too cold, the heat will kick on (or the air conditioning will turn off). In similar fashion, your body is set to maintain a certain level of circulating thyroid hormone.

When thyroid disease or other conditions interfere with the system and the feedback process doesn’t work, however, thyroid problems can develop.

Prevalence of Thyroid Disorders

Thyroid problems are widespread around the world. It is estimated that more than 200 million people worldwide have thyroid disease. Thyroid problems are particularly common in areas covered at one time by glaciers, where iodine is not present in the soil and in foods. In many of these countries, as many as one in five people have an enlarged thyroid, known as goiter, usually due to iodine deficiency. According to the World Health Organization, iodine deficiency is the world’s most prevalent - yet easily preventable - cause of brain damage. It affects more than 780 million people worldwide - 13 percent of the world’s population. As many as an additional 30 percent of the population worldwide is at risk of iodine deficiency–related problems.

Pregnant women with mild iodine deficiency may give birth to children with moderate cognitive and developmental problems - a reduction in IQ of as much as 15 points. Serious iodine deficiency during pregnancy can cause stillbirth, miscarriage, on a congenital abnormality known as cretinism. Cretinism is a severe, irreversible form of mental retardation, and is most common in iodine-deficient areas of Africa and Asia.

In the United States and countries where iodine deficiency is not rampant, other types of thyroid problems are more common, especially the autoimmune disorder known as Hashimoto’s disease. According to the latest diagnostic standards, there are some 54 million people in the United States with thyroid conditions. In the United States, only one in five people with thyroid conditions are actually being treated, however.

In the United States, the majority of thyroid conditions are due to autoimmune disease. The prevalence of thyroid disease increases with age. American women face a one-in-five chance of developing a thyroid problem. Women are seven to eight times more likely than men to develop thyroid conditions.

Besides iodine deficiency and being a woman, other risk factors include genetics and heredity, personal or family history of endocrine or autoimmune disease, infection, exposure to goitrogenic foods, cigarette smoking, pregnancy, certain drugs, particular chemical exposures, and radiation exposure. The risk factors are outlined in detail in Chapter 5.

Thyroid Conditions

There are a number of conditions that can affect the thyroid’s function and structure.

Hypothyroidism or Underactive Thyroid

Hypothyroidism means there is too little thyroid hormone. It can result from a thyroid that is not producing enough hormone, has been radioactively ablated, is affected by drugs or nutritional deficiencies, or is incapable of functioning properly due to nodules, infection, or atrophy. When all or part of the thyroid is removed - as a treatment for cancer, nodules, goiter, Graves’ disease, or hyperthyroidism - the vast majority of patients become permanently hypothyroid. A small number of infants are born without a thyroid, or without a functioning thyroid; this is known as congenital hypothyroidism.

Symptoms of hypothyroidism include fatigue, weight gain, constipation, fuzzy thinking, depression, body pain, slow reflexes, and much more.

Conventional treatment typically involves replacing the missing thyroid hormone using prescription thyroid hormone replacement drugs. Most commonly, a levothyroxine (T4) drug is prescribed, as this is considered the “standard” treatment for hypothyroidism. The most popular levothyroxine drug with physicians is Synthroid, and the term Synthroid is sometimes used to describe “thyroid hormone replacement drugs” (in the same way that the brand name Kleenex has become synonymous with “tissue”). This popularity is mainly due to extensive marketing by the manufacturer, however, and all the brand name levothyroxine drugs (Synthroid, Levoxyl, Levothroid, Unithroid, etc.) are considered to be similar in quality, potency, and effectiveness. Note, however, that Levoxyl has a fast-dissolving formula; it should be taken with plenty of water and swallowed quickly so as to maximize absorption.

Research has shown that many patients feel better with the addition of T3, so increasing numbers of practitioners are prescribing either Cytomel - liothyronine - or, less commonly, levothyroxine plus compounded T3.

Another option is a synthetic T4-T3 combination drug known as liotrix (brand name Thyrolar). While this drug is not commonly prescribed, it is a safe and effective option for some patients.

From the early 1900s to the 1950s, the only form of thyroid replacement drug available was natural thyroid, which was marketed under the brand name Armour Thyroid. The drug fell out of favor with some endocrinologists in the second half of the twentieth century as a result of Synthroid’s extensive marketing efforts. However, since the 1990s, Armour Thyroid has been enjoying a resurgence in popularity with some patients and practitioners. Derived from the desiccated thyroid gland of pigs, the drug contains natural forms of numerous thyroid hormones and nutrients typically found in the actual thyroid gland, and some patients report greater improvement in symptoms using natural thyroid.

Where the thyroid is not surgically removed or chemically deactivated, holistic and integrative treatments focus on support for better thyroid and immune system function, enhancing metabolism and rebalancing the endocrine and hormonal systems through nutrition, herbs, supplements, movement therapy such as yoga, and energy work.

Hyperthyroidism or Overactive Thyroid

Hyperthyroidism - too much throid hormone - can result in thyrotoxicosis. Hyperthyroidism can be caused by a number of thyroid problems, including autoimmune Graves’ disease, nodules that produce thyroid hormone, overdosage of thyroid hormone replacement drugs, or infection. It is typically treated by drugs that reduce the thyroid’s ability to produce hormone, by radioactive iodine treatment to chemically ablate the thyroid, or by surgery.

Symptoms of hyperthyroidism tend to mirror the rapid metabolism that results from an oversupply of thyroid hormone: anxiety, insomnia, rapid weight loss, diarrhea, high heart rate, high blood pressure, eye sensitivity or bulging, vision disturbances, and many other concerns.

Here how Janine describes her hyperthyroidism symptoms:

I started to feel weird, spacey, not feeling right in the head, anxious, heart palpitations, shaky, irritable, lost my appetite, trembling body, losing weight, sweating in the night and
not sleeping, and wondering what in God’s name was wrong with me. I had dizziness and shakiness, my heart pounding, tingling in my right arm and on my right cheek. I knew there was something wrong.

The anxiety of hyperthyroidism can sometimes be so significant that it is mistaken for anxiety or panic disorder. Kelly describes the anxiety of thyroid disease:

I felt like I was on an airplane that was about to crash with uncontrollable, impending doom.

Conventional treatment in the United States focuses on disabling the thyroid permanently by administering radioactive iodine (RAI) treatment, which renders most patients hypothyroid for life. Some physicians use prescription antithyroid drugs such as propylthiouracil (PTU) and methimazole (Tapazole) and beta blockers to calm down the thyroid and the immune system, with the hope of remission of the disease, which occurs in as many as 30 percent of patients. Antithyroid drugs are the first choice for doctors outside the United States. In rare cases in the United States, and more commonly outside the United States, surgery to remove the thyroid may be the treatment. Holistic and integrative treatments prior to RAI or surgery focus on supplementing antithyroid drug approaches with natural antithyroid foods, supplements, and herbs that have no side effects, as well as calming and rebalancing the immune system through nutrition, herbs, supplements, movement therapy such as yoga, and energy work.

Ultimately, most people with hyperthyroidism do end up hypothyroid for life as a result of RAI or surgery.

Goiter

Goiter is the term used to describe an enlargement of the thyroid gland. The thyroid gland can enlarge as a response to deficiencies of iodine, thyroid inflammation or infection, or autoimmune disease. The thyroid becomes large enough that it can be seen as enlarged by ultrasound or X-ray, and may be enlarged enough to thicken the neck area visibly. Particularly large goiters may be cosmetically problematic, and can compromise breathing and swallowing; they are often surgically removed. Smaller goiters may respond to drug treatment.

Symptoms of goiter include a swollen, tender, or tight feeling in the neck or throat; hoarseness or coughing; and difficulty swallowing or breathing.

Goiter can be due to an autoimmune condition that triggers an inflamed thyroid, or too much or too little iodine in the diet. In the United States, 10 to 20 percent of goiters are iodine-induced.

Treatment for goiter depends on how enlarged the thyroid has become, as well as other symptoms. Treatments can include:

* Observation and monitoring, which is typically done if the goiter is not large and is not causing symptoms or thyroid dysfunction.

* Medications, including thyroid hormone replacement, which can help shrink the goiter, or aspirin or corticosteroid drugs, to shrink thyroid inflammation.

* If the goiter is very large, continues to grow despite drug therapy, is in a dangerous location (blocking the windpipe or esophagus), or becomes cosmetically unsightly, most doctors will recommend surgery. If the goiter contains any suspicious nodules, surgery may also be necessary.

Source: The Thyroid Hormone Breakthrough: Overcoming Sexual and Hormonal Problems at Every Age by Mary J Shomon