Anatomy of the Thyroid
The thyroid gland is a butterfly-shaped organ which is composed of two cone-like lobes or wings, connected via a narrower central isthmus. The organ is situated on the anterior side of the neck, lying against and around the larynx and trachea. It is difficult to demarcate the gland’s upper and lower border with vertebral levels because it moves position in relation to these during swallowing.
The thyroid gland is covered by a fibrous sheath, with infrahyoid muscles shielding it from the front and the sternocleidomastoid muscle covering it laterally. The thyroid gland’s firm attachment to the underlying trachea is the reason behind its movement with swallowing. Between the two layers of the capsule and on the posterior side of the lobes, there are two parathyroid glands on each side.
The thyroid gland or simply, the thyroid – not to be confused with the nearby parathyroid glands – is one of the largest endocrine glands in the body. It is found in the neck, below the thyroid cartilage (also known as the Adam’s apple – the thyroid gland gets its name from the Greek word for “shield”, after the shape of this cartilage). The thyroid controls how quickly the body uses energy and makes proteins, and controls how sensitive the body should be to other hormones.
This gland participates in these processes by producing thyroid hormones, the principal ones being triiodothyroninr (T3) and thyroxine (T4). These hormones regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body.
T3 and T4 are synthesized using both iodine and tyrosine. Iodine is an essential substance for thyroid hormone production. As with most substances, either too much or too little can cause problems. Inadequate iodine can lead to thyroid dysfunction and goiter. Studies have shown that excess iodine intake can exacerbate thyroid hormone excess disorders and could even cause an increased prevalence of autoimmune thyroid disease, resulting in permanent hypothyroidism. Another substance produced by the thyroid is calcitonin, which plays a critical role in calcium homeostasis.
The thyroid gland is controlled by the hypothalamus and pituitary (more specifically, the anterior pituitary). The most common problems of the thyroid gland consist of nodules, cancer and an overactive thyroid gland, referred to as hyperthyroidism, and an underactive thyroid gland, referred to as hypothyroidism. These are both considered types of thyroid dysfunction.
What Is Thyroid Dysfunction?
When your body produces too much or too little thyroid hormone, it is called thyroid dysfunction. Thyroid dysfunction is most commonly caused by an autoimmune process in the body, such as those caused by Graves’ disease and Hashimoto’s thyroiditis. An immune attack against the thyroid can, over time, cause too much or too little thyroid hormone to be produced. Thyroid dysfunction can also be caused by abnormal thyroid growths or thyroid surgery.
What Are the Signs and Symptoms of Thyroid Dysfunction?
Hypothyroidism symptoms can sometimes be vague or nonspecific. By far, the most common symptom is fatigue. Other possible symptoms are weight gain, increased sensitivity to cold, constipation, and dry skin, among many others.
Symptoms of hyperthyroidism are similar to symptoms of having a bit too much caffeine. Classic hyperthyroid symptoms include palpitations, anxiety, shakiness, insomnia, increased appetite, and weight loss.
What Are the Risk Factors of Thyroid Dysfunction?
There is no clear preventive method for thyroid dysfunction, and its risk factors are primarily beyond your control. Thyroid dysfunction is generally more common in females. Other risk factors for thyroid dysfunction include having some autoimmune diseases, a family history of thyroid disease, or a family history of other autoimmune diseases.
How Is Thyroid Dysfunction Diagnosed?
Thyroid dysfunction is diagnosed through a blood test – typically the blood tests TSH and free T4. Other thyroid blood tests include T3 levels and antibody levels. TSH (thyroid stimulating hormone) is the hormone that is produced by the pituitary gland in the brain and regulates the amount of thyroid hormones (T3 and T4) produced by the thyroid. Antibodies against the thyroid gland (detected in autoimmune thyroid disease) may also appear in a blood test.
What Are the Possible Treatments for Thyroid Dysfunction?
Hypothyroidism is treated by taking thyroid hormone replacement, typically in the form of a pill. Hyperthyroidism may be treated in several ways. These include medications that block the production of thyroid hormone with a treatment called radioiodine therapy. In some cases, surgery may be necessary.
What Are the Risks if Thyroid Dysfunction Is Left Untreated?
Untreated hypothyroidism can lead to goiter, heart problems, mental health issues, infertility, birth defects, damage to peripheral nerves, and focus issues. In rare cases, unaddressed hypothyroidism can cause a life-threatening condition called myxedema.
Untreated hyperthyroidism can lead to heart problems, brittle bones, and a medical emergency called thyrotoxic crisis or storm which may be life-threatening.
What Are Some Other Disorders Related to the Thyroid?
Hyperparathyroidism: Primary hyperparathyroidism is the most common cause of hypercalcemia (which refers to abnormally high calcium levels in the blood). It typically occurs when one or more of the four parathyroid glands hypertrophy or grow an adenoma that begins to produce extra parathyroid hormone, which in turn increases the calcium levels in the bloodstream. This calcium typically comes from the bones, which is why this can lead to osteoporosis. The symptoms of hypercalcemia usually include “bones, stones, groans, and moans:” bone pain and bone loss, kidney stones, stomach discomfort including reflux, nausea, vomiting, constipation, or diarrhea, and changes in moods and mental status.
Hypoparathyroidism: Hypoparathyroidism is typically a result of surgery on either the thyroid or parathyroids. Because of their close proximity, parathyroids are sometimes accidentally removed or damaged during a thyroid surgery, resulting in a much lower production of parathyroid hormone and a drop in blood calcium levels. This results in muscular irritability which causes symptoms like muscle cramps and tingling.