Thyroid supplements are quickly growing in popularity as more and more people are attracted to products advertising improvements in energy, weight loss, and other benefits. This glossary page covers terms and concepts related to the thyroid and thyroid supplements.
Desiccated Thyroid
A dried and powdered version of cow or pig thyroid tissue that is used in some thyroid supplements. Desiccated thyroid contains both thyroid hormones (T4 and T3).
Facticious Hyperthyroidism
Elevated thyroid hormone levels caused by taking thyroid supplements or drugs, typically ones that contain synthetic or animal-derived thyroid hormones. The symptoms are the same as normal hyperthyroidism.
Goiter
Enlargement of the thyroid gland visible as swelling in the neck. A goiter by itself is harmless, but may indicate an underlying thyroid condition.
Grave’s Disease
An autoimmune condition characterized by the body producing antibodies that stimulate the thyroid, causing it to enlarge and produce more hormones than needed. This disorder is the number one cause of hyperthyroidism.
Hashimoto’s Thyroiditis
An autoimmune disorder in which the body’s immune system mistakenly attacks the thyroid, causing it to malfunction and produce less hormones than needed. This condition is the main cause of hypothyroidism.
Hypothalamus
A region of the brain that produces several important hormones. In terms of thyroid health, the hypothalamus is important for producing thyrotropin-releasing hormone (TRH), a hormone that stimulates the pituitary gland to release TSH, which in turn stimulates thyroid hormone production.
Hypothyroidism
The most common thyroid condition, characterized by an underactive thyroid that doesn’t produce enough hormone. Symptoms of hypothyroidism include weight gain, fatigue, brain fog, memory problems, depression, cold sensitivity, constipation, and dry skin.
Hyperthyroidism
This disorder is characterized by an overactive thyroid gland that makes too much hormone. Symptoms of hyperthyroidism include weight loss, fatigue, anxiety, nervousness, insomnia, and rapid heartbeat.
Metabolism
The set of biochemical reactions required to sustain life. Metabolism can be roughly divided into cabatolic reactions that break down food to release energy, and anabolic reactions that use energy to produce life-essential molecules such as proteins.
Pituitary Gland
A small gland that produces multiple hormones, located underneath the hypothalamus in the brain. The pituitary is responsible for producing the hormone TSH that is needed to tell the thyroid gland to produce its hormones.
Postpartum Thyroid Dysfunction (PPTD)
An inflammatory thyroid condition similar to Hashimoto’s thyroiditis and hypothyroidism that occurs in the 12 months after giving birth.
Thyroiditis
A term for any kind of thyroid inflammation. Thyroiditis is typically caused by autoimmune disorders such as Graves’ disease.
Thyroid-stimulating hormone (TSH)
A hormone produced by the pituitary gland that signals the thyroid to produce its two hormones – triiodothyronine and thyroxine.
Thyroid Storm
A rare, severe complication of hyperthyroidism that occurs when thyroid hormone levels are extremely high. The symptoms of thyroid storm are similar to hyperthyroidism but more serious, and can be life-threatening if not addressed quickly.
Thyrotoxicosis
A condition in which thyroid hormone levels in the body are abnormally high. Although this term is often used interchangeably with hyperthyroidism – which is the main cause of thyrotoxicosis – they are not the same thing. Indeed, it is possible to have thyrotoxicosis without hyperthyroidism, such as when taking too much thyroid hormone to deal with hypothyroidism.
Thyrotropin-releasing hormone (TRH)
A hormone produced by the brain’s hypothalamus that stimulates the release of TSH by the pituitary gland.
Thyroxine (T4)
The main thyroid hormone released into the blood. T4 is considered inactive, and must first be converted into the more potent T3 by the kidneys, liver, and other tissues. The large majority of thyroid supplements and medications that contain thyroid hormone use a synthetic or animal version of T4.
Triiodothyronine (T3)
The second, active form of thyroid hormone released into the blood. The thyroid produces relatively small amounts of T3, because most of it comes from the conversion of T4 into T3 that occurs after T4 enters certain organs and tissues.
