Thyroid Disorders Types, Symptoms, Causes, Risk factors, Complications, Diagnosis, Treatment , FAQs

Thyroid disorders are a medical condition that affects the function of the thyroid gland. The thyroid gland is located at the front of the neck and produces thyroid hormones that travel through the blood to help regulate many other organs, meaning that it is an endocrine organ. These hormones normally act in the body to regulate energy use, infant development, and childhood development.

A properly functioning thyroid will maintain the right amount of hormones needed to keep the body’s metabolism functioning at a satisfactory rate. As the hormones are used, the thyroid creates replacements.

Thyroid Disorders Types

There are specific kinds of thyroid disorders that include:

• Hypothyroidism
• Hyperthyroidism
• Goiter
• Thyroid nodules
• Thyroid cancer

Hypothyroidism

describes excessive production of thyroid hormone, a less common condition than hypothyroidism. Symptoms of hypothyroidism usually relate to increased metabolism. In mild cases, there may not be apparent symptoms. Symptoms and signs of hyperthyroidism can include:

• Tremor
• Nervousness
• Fast heart rate
• Fatigue
• Intolerance for heat
• Increase in bowel movements
• Increased sweating
• Concentration problems
• Unintentional weight loss

Some of the most common causes of hyperthyroidism are:

• Graves’ disease
• Toxic multinodular goiter
• Thyroid nodules that overexpress thyroid hormone (known as “hot” nodules)
• Excessive iodine consumption

Thyroid Disorders Signs and symptoms

Symptoms of the condition vary with type: hypo- vs. hyperthyroidism, which are further described below.

• Possible symptoms of hypothyroidism are:
• Tiredness
• Unexplained weight gain
• Slow movement
• Muscle cramps
• Slow heart rate (bradycardia)
• Sensitivity to cold temperatures
• Constipation
• Depressed mood
• Memory difficulty

Possible symptoms of hyperthyroidism are:

• Difficulty sleeping (insomnia)
• Unexplained weight loss
• Tremors
• Fast heart rate (tachycardia) or palpitations
• Sensitivity to hot temperatures, excess sweating
• Diarrhea
• Anxiety, irritability

Thyroid Disorders Causes

When your thyroid doesn’t produce enough hormones, the balance of chemical reactions in your body can be upset. There can be several causes, including autoimmune disease, hyperthyroidism treatments, radiation therapy, thyroid surgery, and certain medications.

Your thyroid is a small, butterfly-shaped gland situated at the base of the front of your neck, just below your Adam’s apple. Hormones produced by the thyroid gland — triiodothyronine (T3) and thyroxine (T4) — have an enormous impact on your health, affecting all aspects of your metabolism. These hormones also influence the control of vital functions, such as body temperature and heart rate.

Hypothyroidism results when the thyroid gland fails to produce enough hormones. Hypothyroidism may be due to many factors, including:

• Autoimmune disease. The most common cause of hypothyroidism is an autoimmune disorder known as Hashimoto’s thyroiditis. Autoimmune disorders occur when your immune system produces antibodies that attack your tissues. Sometimes this process involves your thyroid gland. Scientists aren’t sure why this happens, but it’s likely a combination of factors, such as your genes and an environmental trigger. However it happens, these antibodies affect the thyroid’s ability to produce hormones.
• Over-response to hyperthyroidism treatment. People who produce too much thyroid hormone (hyperthyroidism) are often treated with radioactive iodine or anti-thyroid medications. The goal of these treatments is to get thyroid function back to normal. But sometimes, correcting hyperthyroidism can end up lowering thyroid hormone production too much, resulting in permanent hypothyroidism.
• Thyroid surgery. Removing all or a large portion of your thyroid gland can diminish or halt hormone production. In that case, you’ll need to take thyroid hormone for life.
• Radiation therapy. Radiation used to treat cancers of the head and neck can affect your thyroid gland and may lead to hypothyroidism.
• Medications. Some medications can contribute to hypothyroidism. One such medication is lithium, which is used to treat certain psychiatric disorders. If you’re taking medication, ask your doctor about its effect on your thyroid gland.

Less often, hypothyroidism may result from one of the following:

• Congenital disease. Some babies are born with a defective thyroid gland or no thyroid gland. In most cases, the thyroid gland didn’t develop normally for unknown reasons, but some children have an inherited form of the disorder. Often, infants with congenital hypothyroidism appear normal at birth. That’s one reason why most states now require newborn thyroid screening.
• Pituitary disorder. A relatively rare cause of hypothyroidism is the failure of the pituitary gland to produce enough thyroid-stimulating hormone (TSH) — usually because of a benign tumor of the pituitary gland.
• Pregnancy. Some women develop hypothyroidism during or after pregnancy (postpartum hypothyroidism), often because they produce antibodies to their thyroid gland. Left untreated, hypothyroidism increases the risk of miscarriage, premature delivery, and preeclampsia — a condition that causes a significant rise in a woman’s blood pressure during the last three months of pregnancy. It can also seriously affect the developing fetus.
• Iodine deficiency. The trace mineral iodine — found primarily in seafood, seaweed, plants are grown in iodine-rich soil and iodized salt — is essential for the production of thyroid hormones. Too little iodine can lead to hypothyroidism, and too much iodine can worsen hypothyroidism in people who already have the condition. In some parts of the world, iodine deficiency is common, but the addition of iodine to table salt has virtually eliminated this problem in the United States.

Thyroid Disorders Risk factors

Although anyone can develop hypothyroidism, you’re at an increased risk if you:

• Are a woman
• Are older than 60
• Have a family history of thyroid disease
• Have an autoimmune disease, such as type 1 diabetes or celiac disease
• Have been treated with radioactive iodine or anti-thyroid medications
• Received radiation to your neck or upper chest
• Have had thyroid surgery (partial thyroidectomy)
• Have been pregnant or delivered a baby within the past six months

Thyroid Disorders Complications

Untreated hypothyroidism can lead to many health problems:

• Goiter. Constant stimulation of your thyroid to release more hormones may cause the gland to become larger — a condition is known as a goiter. Although generally not uncomfortable, a large goiter can affect your appearance and may interfere with swallowing or breathing.
• Heart problems. Hypothyroidism may also be associated with an increased risk of heart disease and heart failure, primarily because high levels of low-density lipoprotein (LDL) cholesterol — the “bad” cholesterol — can occur in people with an underactive thyroid.
• Mental health issues. Depression may occur early in hypothyroidism and may become more severe over time. Hypothyroidism can also cause slowed mental functioning.
• Peripheral neuropathy. Long-term uncontrolled hypothyroidism can cause damage to your peripheral nerves. These are the nerves that carry information from your brain and spinal cord to the rest of your body — for example, your arms and legs. Peripheral neuropathy may cause pain, numbness, and tingling in affected areas.
• Myxedema. This rare, life-threatening condition is the result of long-term, undiagnosed hypothyroidism. Its signs and symptoms include intense cold intolerance and drowsiness followed by profound lethargy and unconsciousness.A myxedema coma may be triggered by sedatives, infection or other stress on your body. If you have signs or symptoms of myxedema, you need immediate emergency medical treatment.
• Infertility. Low levels of thyroid hormone can interfere with ovulation, which impairs fertility. Also, some of the causes of hypothyroidism — such as autoimmune disorder — can also impair fertility.
• Birth defects. Babies born to women with untreated thyroid disease may have a higher risk of birth defects compared to babies born to healthy mothers. These children are also more prone to serious intellectual and developmental problems. Infants with untreated hypothyroidism present at birth are at risk of serious problems with both physical and mental development. But if this condition is diagnosed within the first few months of life, the chances of normal development are excellent.

In addition to thorough medical history and physical exam, specialized tests are used to diagnose thyroid disorders.

Blood tests are typically done to measure levels of thyroid hormones and TSH. Blood tests to identify antibodies against thyroid tissue may also be ordered by your doctors, such as titers of anti-thyroglobulin, anti-thyroperoxidase, or TSH receptor stimulating antibodies.

Imaging tests are commonly used when thyroid nodules or enlargement are present. Ultrasound can visualize the consistency of the tissue within the gland and can often reveal cysts or calcifications. Ultrasound examination cannot distinguish a benign from a malignant process.

Thyroid scans using radioactive iodine are often performed to evaluate the function of thyroid nodules. The thyroid is the only location in the body that takes up iodine, so when radioactively labeled iodine is given, it is taken up by the thyroid gland. An imaging test typically shows uptake of radioactive iodine by normal thyroid tissue.

Areas or nodules that are producing excess hormone (referred to as hyperfunctioning) will show increased uptake of iodine. These are referred to as “hot” nodules or areas. By contrast, the so-called “cold” nodules represent areas with decreased iodine uptake. “Cold” nodules do not produce excess hormone and can sometimes represent cancer.

Fine needle aspiration and biopsy are techniques that remove a sample of cells or tissue from the thyroid gland for examination and diagnosis by a pathologist, who is a physician trained in the diagnosis of conditions based on tissue samples. Fine needle aspiration (FNA) uses a long, thin needle to withdraw a sample of cells from the thyroid. FNA can be performed in the doctor’s office. Sometimes, ultrasound imaging is used to guide the FNA procedure. A biopsy is the surgical sampling of tissue.

Thyroid Disorders Frequently Asked Questions (FAQs)

What is the thyroid gland?

The thyroid is a butterfly-shaped gland that sits low in your neck along the front of the trachea (windpipe). It has two lobes, left and right, and is connected by a band of tissue, called the isthmus. It is responsible for secreting thyroid hormones, which act throughout the body to influence metabolism, growth and development, and body temperature. It is located near several important structures including the superior and recurrent laryngeal nerves (which control the vocal cords) and the parathyroid glands (which regulate the body’s calcium levels).

What is thyroid disease?

Thyroid disease encompasses a large variety of problems with the thyroid. The thyroid can become underactive (hypothyroid) or overactive (hyperthyroid) for many different reasons. Blood tests are usually the first step in diagnosing thyroid disease. The thyroid can also become enlarged (goiter) or develop nodules (growths within the thyroid). Based on physical exam and blood tests your doctor can determine if other studies are needed such as ultrasound, thyroid scan, or biopsy and the appropriate treatment.

What does the thyroid do?

The thyroid gland uses iodine to produce thyroid hormones — primarily thyroxine (T4) and triiodothyronine (T3). T4 gets converted into T3 (a more active form) in the blood. Thyroid hormones regulate our metabolic rate and affect weight and energy levels. The thyroid also produces calcitonin, which contributes to calcium balance. Thyroid hormone production is regulated by a feedback system involving the pituitary gland (a small gland at the base of the brain).

When should I see a doctor about my thyroid?

There are two general reasons to see a doctor about your thyroid: problems with thyroid function (hormone levels) and thyroid nodules (a lump or growth in the thyroid).  Please see below for more detailed answers.

How do I know if I have an underactive thyroid?

Signs and symptoms of low thyroid function are highly variable from person to person. Symptoms of an underactive thyroid may include fatigue, weight gain, cold intolerance, more sluggish bowels, dry skin, brittle nails, hair loss, muscle pains, mood changes and alteration in the menstrual cycle. But, these symptoms are non-specific and may be due to other issues if thyroid levels are within normal limits.

What are the causes of an underactive thyroid? 

The main causes of underactive thyroid (primary hypothyroidism) are surgery (thyroid removal), radioactive iodine treatment (to destroy the thyroid gland) and chronic autoimmune hypothyroidism or Hashimoto’s Thyroiditis. Hashimoto’s Thyroiditis is defined by the presence of an antibody that may impact thyroid function over time.

A far more significant percentage of the population has thyroid antibodies (11% in some studies) than have low thyroid function (4% in some studies). This means that even if you do have the antibody, your thyroid function may remain normal and you may not require thyroid replacement medication.

What should I ask my doctor to check for?  

If you are concerned that your thyroid is not functioning properly, Thyroid Stimulating Hormone (TSH) is the initial blood test to check. TSH is the most sensitive test for thyroid dysfunction because small changes in T4 levels cause relatively larger changes in TSH. Further evaluation can be done with free T4 levels and antibodies for Hashimoto’s Thyroiditis, in the appropriate clinical setting.

In most cases, thyroid disorders can be well managed with medical treatment and are not life-threatening. Some conditions may require surgery. The outlook for most people with thyroid cancer is also good, although patients with thyroid cancer that has spread throughout the body have a poorer prognosis.

What is thyroid disease?

When the thyroid produces too much hormone, the body uses energy faster than it should. This condition is called hyperthyroidism. When the thyroid doesn’t produce enough hormone, the body uses energy slower than it should. This condition is called hypothyroidism. There are many different reasons why either of these conditions might develop.