Your thyroid is a small butterfly-shaped endocrine gland located in the middle of your lower neck, just over the windpipe. Its job is controlling the body’s metabolism—the basic processes that turn food and water into energy so we can function and live our lives.

In order to control metabolism, the thyroid gland produces hormones that are secreted into the blood, which then carries the hormones throughout your body. Those hormones help the body use energy, stay warm, and keep the brain, heart, muscles and other organs working like they should.

The growth and development of all your body tissues are dependent on your thyroid working properly. If your thyroid is overactive or underactive, that can create health problems called thyroid disorders like hyperthyroidism or hypothyroidism.

What is hyperthyroidism?

Hyperthyroidism occurs when your thyroid overproduces a hormone called thyroxine. When that happens, it causes your metabolism to speed up which creates symptoms like weight loss, sweating, anxiety, and tremors.

What causes hyperthyroidism?

• Graves’ disease: This is the most common cause (in more than 70% of people) of hyperthyroidism. A person suffers from this condition when antibodies in the blood stimulate the Thyroid gland to grow and secrete excessive thyroid hormones. This kind of a disorder is usually hereditary and surprisingly, more often than not, young women tend to be its victims.

• Thyroid nodules: Another cause of hyperthyroidism is also the presence of one or more lumps—called nodules—in the thyroid gland. These gradually grow and become overactive, releasing excessive thyroid hormones into the bloodstream.

• Thyroiditis: Thyroiditis, or inflammation of the thyroid, is usually caused by a problem with the immune system or a viral infection or by the intake of excessive Thyroid hormone in the tablet forms. This disorder can be both painful and painless; the painless variety occurs most frequently in women after childbirth.

What is hypothyroidism?

In contrast to hyperthyroidism, hypothyroidism refers to an underactive thyroid that doesn’t produce enough of those hormones that regulate metabolism.

What causes hypothyroidism?

• Autoimmune diseases: Sometimes, the immune system mistakes the thyroid gland cells and their enzymes as invaders and attacks them. That causes a shortage of thyroid cells and enzymes left to produce thyroid hormone. This condition is known as Autoimmune thyroiditis. This is more common in women than men and may begin suddenly or develop slowly over many years.

• Surgical removal: If part or all of your thyroid gland is removed for a certain reason—nodules, cancer, or Graves’ disease—chances are that you may begin to suffer from hypothyroidism. If you’ve had your whole thyroid removed, the surgery will result hypothyroidism. If only a part of the gland is removed, thyroid levels may still remain within normal limits, provided the un-removed glands function as they should.

• Radiation treatment: Sometimes, radioactive iodine is used to destroy the thyroid gland in people with a thyroid disorder or certain cancers of the head and neck. This usually results in loss of part or all of the thyroid function.

• Inherited disease: Hypothyroidism can also be passed on to an unborn child in the womb. Some babies are born without the thyroid gland or with only a partly formed one. Occasionally, some infants will be born with part or all of their thyroid in the wrong place (Ectopic Thyroid). For others, the thyroid cells or their enzymes do not function properly.

• Inflammation of the thyroid: Thyroiditis (an inflammation of the thyroid gland usually caused by an autoimmune attack or by a viral infection) makes the thyroid gland release all its stored supply of thyroid hormone into the blood at one time. This causes a temporary period of hyperthyroidism, later followed by hypothyroidism.

• Certain medicines: Some drugs can trigger hypothyroidism and prevent the thyroid gland from being able to produce the hormones. This is especially true in the case of patients who have a genetic tendency towards autoimmune thyroid disease.

• Too much or too little iodine: Iodine is essential to produce thyroid hormone, but too much or too little can cause or worsen hypothyroidism.

• Damaged pituitary gland: When your pituitary gland is damaged because of disease or surgery, it may no longer be able to regulate the production and release of thyroid hormones.

• Rare disorders: Some diseases cause deposits of abnormal substances in the thyroid gland, impairing its ability to function. For example, Sarcoidosis may deposit granulomas or small areas of inflammation and hemochromatosis can cause iron deposits.