The thyroid regulates your metabolism.
The two main thyroid hormones are T3 and T4.
Thyroid disorders are common, and they include goiters, hyperthyroidism, and hypothyroidism.
The thyroid’s main role in the endocrine system is to regulate your metabolism, which is your body’s ability to break down food and convert it to energy. Food essentially fuels the body, and each of our bodies uses that fuel at different rates. This is why you often hear about some people having a “fast” metabolism and others having a “slow” metabolism.

The thyroid keeps your metabolism under control through the action of thyroid hormone, which it makes by extracting iodine from the blood and incorporating it into thyroid hormones. Thyroid cells are unique in that they are highly specialized to absorb and use iodine. Every other cell depends on the thyroid to manage its metabolism.

The pituitary gland and hypothalamus both control the thyroid. When thyroid hormone levels drop too low, the hypothalamus secretes TSH Releasing Hormone (TRH), which alerts the pituitary to produce thyroid stimulating hormone (TSH). The thyroid responds to this chain of events by producing more hormones. To learn more, read our article about how the thyroid works.

Anatomy of the Thyroid
Derived from the Greek word meaning shield, the thyroid is a butterfly-shaped gland located in front of the windpipe (called the trachea) and just below the larynx or Adam’s apple in the neck. It is comprised of two halves, known as lobes, which are attached by a band of thyroid tissue called the isthmus.

During development, the thyroid is actually located in the back of the tongue and has to migrate to the front of the neck before birth. There are rare instances when the thyroid migrates too far or too little. There are even cases when the thyroid remains in the back of the tongue—this is known as lingual thyroid.

Hormones of the Thyroid
The two main hormones the thyroid produces and releases are T3 (tri-iodothyronine) and T4 (thyroxine). A thyroid that is functioning normally produces approximately 80% T4 and about 20% T3, though T3 is the stronger of the pair.

To a lesser extent, the thyroid also produces calcitonin, which helps control blood calcium levels.

Diseases and Disorders of the Thyroid
There are many diseases and disorders associated with the thyroid. They can develop at any age and can result from a variety of causes—injury, disease, or dietary deficiency, for instance. But in most cases, they can be traced to the following problems:
Too much or too little thyroid hormone (hyperthyroidism and hypothyroidism, respectively).

Abnormal thyroid growth
Nodules or lumps within the thyroid
Thyroid cancer

Some of the Most Common Thyroid Disorders.

Goiters: A goiter is a bulge in the neck. A toxic goiter is associated with hyperthyroidism, and a non-toxic goiter, also known as a simple or endemic goiter, is caused by iodine deficiency.

Hyperthyroidism: Hyperthyroidism is caused by too much thyroid hormone. People with hyperthyroidism are often sensitive to heat, hyperactive, and eat excessively. Goiter is sometimes a side effect of hyperthyroidism. This is due to an over-stimulated thyroid and inflamed tissues, respectively.

Hypothyroidism: Hypothyroidism is a common condition characterized by too little thyroid hormone. In infants, the condition is known as cretinism. Cretinism has very serious side effects, including abnormal bone formation and mental retardation. If you have hypothyroidism as an adult, you may experience sensitivity to cold, little appetite, and overall sluggishness. Hypothyroidism often goes unnoticed, sometimes for years, before being diagnosed.

Solitary thyroid nodules: Solitary nodules, or lumps, in the thyroid are actually quite common—in fact, it’s estimated that more than half the population will have a nodule in their thyroid. The great majority of nodules are benign. Usually, a fine needle aspiration biopsy (FNA) will determine if the nodule is cancerous.

Thyroid cancer: Thyroid cancer is fairly common, though long-term survival rates are excellent. Occasionally, symptoms such as hoarseness, neck pain, and enlarged lymph nodes occur in people with thyroid cancer. Thyroid cancer can affect anyone at any age, though women and people over thirty are most likely to develop the condition.

Thyroiditis: Thyroiditis is an inflammation of the thyroid that may be associated with abnormal thyroid function (particularly hyperthyroidism). Inflammation can cause the thyroid’s cells to die, making the thyroid unable to produce enough hormones to maintain the body's normal metabolism. There are five types of thyroiditis, and the treatment is specific to each

The human body works as directed by the various hormones released by the endocrine system. These hormones are essential for coordination of various body functions. From the height a person achieves to the metabolic reactions in the body to the reproductive cycle to the stress levels a person can handle, all are hormone controlled.

Pregnancy is another critical, complicated phase that a woman goes through. It is one of the most awaited phases in a woman’s life; however, it is not very simple either. The above-noted hormones play a major role in this pregnancy, as the baby is dependent on the mother for its initial supply of hormones until it can start producing its own hormones. If the baby does not receive the require amounts, there could be various detrimental effects during development and post birth.

Hypothyroidism or an underactive thyroid is extremely common in women and there are multiple theories about how hypothyroidism can affect a woman’s chances of getting pregnant. While the correlation between hypothyroidism and pregnancy are quite well researched, a strong connection stating hypothyroid women being not able to be pregnant is yet to be proven.

The following are some correlations between hypothyroidism and pregnancy.

Increased chance of miscarriage: Women with reduced thyroid functions have double the chances of having a miscarriage. Women suffering from thyroid are at a risk of recurrent miscarriages during the first trimester. The chances of miscarriages during the second trimester are also about 40% higher in hypothyroid women. These women are also at a risk of:

Premature labour

Low birth weight

Increased chances of stillbirth

Maternal anemia

Postpartum hemorrhage

Developmental defects and/or delays in the newborn

Placental abruption

High blood pressure

One of the reasons identified for infertility in women is hypothyroidism. This range varies from 1% to 40% and so remains to be proven still. In addition, the hypothyroid mother will have a set of symptoms to live through, which may be further complicated given the pregnancy. Thyroid replacement should be religiously done and monitored to ensure TSH levels are at the optimal required levels (2.5 to 3 mIU/L) during the entire duration of pregnancy.

If you have the following, be sure to go through a comprehensive thyroid screening before and during pregnancy.

Family history of thyroid

History of thyroid dysfunction or goitre or thyroid antibodies

Clinical signs and symptoms suggestive of hypothyroidism

History of repeated miscarriages

History of head and neck radiation

Family/personal history of autoimmune disorders

While it still remains to be proven that hypothyroidism per se can stop a woman from being pregnant, there are definitely effects of hypothyroidism on the developing child and the mother. A comprehensive screening and close monitoring through pregnancy are extremely essential.

The body has multiple chemicals called hormones, which regulate many of its functions. Increased or decreased levels of these hormones affect various functions including metabolism, growth and sexual functions. Thyroxin produced by the thyroid (situated in the front of the neck) is one such hormone, which has a significant role to play in metabolism.

Graves’ disease is one of the main causes of hyperthyroidism, where there is excessive production of thyroid hormones. Graves’ disease is an autoimmune disorder, wherein the body reacts against its own tissues. It is very common in women than men, especially after 20 years of age. Family history also has a strong correlation in developing Graves’ disease. The high levels of thyroid hormone increase the rate of metabolism, thereby altering weight, mental energy levels, physical stamina, and also mood.

Thyroid hormone is related to metabolism and more amount of it lead to higher metabolism. This causes the following symptoms.

1. Intolerance to heat

2. Excessive sweating

3 .Nervousness and anxiety

4. Inability sleep, as the mind is always excited

5. Increased appetite (sometimes despite weight loss) due to higher metabolism

6. Irregular menstrual cycles

7. Palpitations (rapid, loud heartbeat)

8. Irregular heartbeats (tachyarrhythmia)

9. Fine tremors of the extended arms

10. Breast enlargement in men, known as gynecomastia

11. Extreme moodiness, causing irritability and anger

12. Inability to focus and concentrate

13. General fatigue and shortness of breath with any exertion

14. Increased frequency of bowel movements

In addition, the eye symptoms are quite diagnostic including:

-Protrusion of the eyes (exophthalmos), giving an impression that they are going to fall out
-Double vision
-Excessive tearing
-Increased irritation in the eyes

Diagnosis: The first symptom would be the presence of an enlarged thyroid gland (front of the neck above the collarbone), and the some of the above symptoms would be present.
In addition, tests to check for thyroid gland functioning including T3 and T4 levels would reveal increased amounts of hormone in the blood stream.

As a confirmatory test, the radioactive iodine uptake test also is done, which will indicate increased uptake by the thyroid gland. This indicates that the gland is functioning at an increased pace and requires additional iodine for the production of thyroid hormones.

Treatment: There are two approaches to it, one to control the symptoms and the other to control the thyroid gland per se.

1. Beta blockers are very useful in controlling rapid heart rate and anxiety.

2. Prednisone may be used to control eye irritation and swelling

3. Antithyroid drugs are used to control the production of thyroid

4. Radioactive iodine is given orally to control excessive thyroid production

5. In severe cases, thyroid gland may be surgically removed partially or completely

Graves’ disease is not life-threatening and once symptoms are controlled, the patient’s quality of life improves drastically.

Thyroid disorders are associated with the thyroid gland. A thyroid gland is a butterfly-shaped gland situated right at the base of one’s neck. The role of the thyroid gland is to carry out numerous metabolic processes within the body. The brain regulates the functioning of the thyroid gland through a feedback mechanism. There are a number of disorders, both severe and trivial, which could affect the thyroid gland.

Main symptoms of thyroid disorders:

Weight loss and weight gain

Changes in heart rate (arrhythmia)

Hair loss

Frequent mood swings

Swollen neck

Sudden bouts of moderate to high fever

Other symptoms include:

Numbness or a tingling sensation in the hands

Constipation

Abnormalities or irregularities in menstruation

Brittle nails and dry skin

Blurred vision

Weakened muscle tone and frequent tremors in the body

Treatment Options:


Intake of thyroid hormone pills may prove beneficial. Once you start with the treatment, you may notice significant improvement within the first two or three weeks. Generally, once affected by thyroid disorders, one might have to be on these medications his/her entire life. Over time, this treatment procedure should result in lowering of the cholesterol levels, increased energy; but in certain cases, might throw up side effects in the form of sudden and unexplained weight loss.

Anti-thyroid medications help reduce and regulate the secretion of the thyroid hormone, thus treating certain thyroid disorders (such as hyperthyroidism).

Beta blockers are drugs help in reducing high blood pressure, heart palpitations and controlling heart rate.

In severe cases, such as enlargement of the thyroid gland, surgery is advised by the doctor, in which the thyroid gland is removed. Tumors or thyroid nodules are also treated by this surgical process.

In cases of thyroid cancer, besides the surgical procedure, radioactive iodine therapy (radioiodine) is recommended. This therapy helps destroy the thyroid gland and other thyroid (malignant) cells which may be taking up iodine. However, the side effects of this technique are minimal. This procedure helps to destroy those tissues which may not have been removed by the surgery. If the thyroid cancer has spread to the lymph nodes or to other parts within the body, this particular mode of treatment can be very effective.

Types of Thyroid Disorders:

Hypothyroidism: This is a condition characterized by an underactive thyroid gland. In this case, sufficient thyroid hormone is not secreted in the body.

Hyperthyroidism: This is characterized by an overactive thyroid gland, that results in overproduction of the thyroid hormone.

Thyroid cancer: It is a type of cancer of the thyroid gland.

Goiter: This is a disorder wherein the thyroid gland gets abnormally enlarged.

Thyroid nodules: This is marked by swelling of the thyroid gland.

THE THYROID IS A LITTLE POWERHOUSE.
The butterfly-shaped gland, which lives in the base of your neck, is frequently associated with everything from fatigue to excess pounds — for good reason. "Thyroid hormones affect nearly every organ and process in the body," says Angela Leung, M.D., assistant clinical professor of medicine in UCLA's Division of Endocrinology. How it works: Thyroid-stimulating hormone (TSH), released by the brain's pituitary gland, tells the thyroid to produce and release thyroxine (T4). You metabolize T4 into a more usable form, T3, which goes out into the body to accomplish its mile-long to-do list.

THYROID ISSUES ARE PREVALENT IN WOMEN.
About 10 percent of women have some form of hypothyroidism, in which the thyroid gland can't make sufficient thyroid hormones to keep the body humming smoothly, reports the ATA. Women are up to eight times more likely to experience it as men, and the Mayo Clinic says those over 60 are at even higher risk. Less frequent (affecting about 1 percent of Americans) is hyperthyroidism, in which excess thyroid hormone is produced.


THE SYMPTOMS ARE OFTEN SUBTLE AT FIRST, YET HARMFUL LATER.
When the thyroid slows down, you slow down. Your metabolism loses steam, your energy slumps, you feel colder and weaker, your heart rate drops, and your brain fogs. Hypothyroidism has also been linked to an increased risk of type 2 diabetes and infertility. (The opposite happens with hyperthyroidism, which causes bodily functions to speed up.)

HORMONAL CHANGES CAN BE CONFUSED WITH THYROID PROBLEMS.
Your risk of thyroid issues increases with age, and perimenopause usually starts in your 40s. Since hypothyroidism shares many of the same symptoms, such as fatigue, erratic periods, and weight gain, it can be hard for women to tease the two issues apart initially, says Dr. Leung. Clues that your symptoms might be thyroid-related instead of menopausal: You have a family history of thyroid disease (ask your mother or a female relative if you're not sure) or you have an autoimmune problem such as type 1 diabetes or celiac disease. Inflammation caused by an autoimmune disease known as Hashimoto's disease, which happens when your immune system attacks the thyroid, is the most common cause of hypothyroidism.

DOCTORS USE THE SAME TESTS TO CHECK THYROID LEVELS, BUT THEIR RECOMMENDATIONS MAY DIFFER.
The first step in investigating a potential sign of thyroid problems is to check your TSH level, which your doctor does via a quick blood test. If your TSH is high or abnormal, it could mean your thyroid isn't functioning well and your body is trying to release more TSH to tell your thyroid to get moving. But what's considered "normal" is subjective. Many experts consider the normal range for TSH to be from 0.5 to 5 mIU/L, so if your test results come back within this window, your doc may not suggest treatment. Other experts, typically integrative or holistic-minded physicians, might consider treatment if your levels are technically in the normal range (say, 2.5 to 4 mIU/L) but you're experiencing symptoms. Your doctor may also want to test your T3 or T4 level to get a better sense of your thyroid health.

TREATMENT CAN BE VERY EFFECTIVE.
Levothyroxine—synthetic T4—is one of the most prescribed drugs in the U.S., more common than amoxicillin or Lipitor. It's relatively inexpensive (about $13 per month for the generic form) and has few side effects. Although the medication is safe, you need to take it at the same time every morning on an empty stomach, an hour before eating. If it works, you need to be on it in some form for the rest of your life, says Juan Brito, M.D., an endocrinologist at the Mayo Clinic, which is why experts caution against the pills unless you truly have a thyroid disorder.

THE THYROID CAN BE A SCAPEGOAT FOR OTHER HEALTH PROBLEMS.
It's true that symptoms like weight gain, fatigue, and low sex drive are sometimes wrongly blamed on the thyroid. That's why it's important for doctors to look at everything — test results, symptoms, and risk factors — in context rather than as stand-alone issues, says Melinda Ring, M.D., executive director of Northwestern Medicine's Osher Center for Integrative Medicine in Chicago. Knowing what's typical for your body and working with a doctor to sort through concerns will help provide answers. An internist or a primary care physician is a great person to start with. Along with conducting blood tests, he or she will look for other issues that might be masquerading as hypothyroid symptoms: Fatigue, for example, could indicate a vitamin deficiency. From there, you may be referred to an endocrinologist if necessary.

WHEN AND WHAT YOU EAT CAN HELP YOUR THYROID.
Eating smaller, more frequent meals throughout the day may have a positive impact on T3 levels, suggests new research from Rush University Medical Center in Chicago. Scientists say it could happen because when you increase levels of insulin, it helps the body turn T4 into T3.

EATING MORE FOODS WITH SELENIUM CAN ALSO HELP.
One study found that selenium might help prevent thyroid damage in people with Hashimoto's thyroiditis, an autoimmune condition that can lead to hypothyroidism. (Selenium is needed to make thyroid hormones.) The recommended daily amount for women is 55 mcg per day; you can find it in seafood, Brazil nuts, and eggs.

KNOW WHEN TO GET SCREENED.
While most medical organizations do not endorse routine thyroid screening for healthy individuals, it's a good idea for pregnant women. "Thyroid hormone is important for the developing fetus," says Shanti Serdy, M.D., a staff physician at Boston's Joslin Diabetes Center specializing in thyroid health and an instructor of medicine at Harvard Medical School. You may also want to get screened if you have risk factors such as a family history of thyroid disease or a personal or family history of autoimmune conditions.

TALK TO YOUR PHYSICIAN.
If you know something is off, go with your gut. Exercising her voice and working with different medical practitioners was critical for Mary Shomon, 56, of Gaithersburg, MD, who was diagnosed with hypothyroidism in 1995 and tried numerous medications before finding a combination that worked. (In addition to T4, she needed a daily boost of T3 before her symptoms of weight gain, fatigue, and the blues finally subsided.) Now a thyroid-health activist and author, she encourages women not to give up. "What's normal for one woman may not be normal for another," she says. "I'm thankful I found someone to treat me as a patient, not a number. It changed everything."