Home > Health A – Z > Hypothyroidism

Hypothyroidism

Too little thyroid hormone. Symptoms include weight gain, constipation, dry skin, and sensitivity to the cold. Also called underactive thyroid.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Hypothyroidism

The thyroid gland performs a vital function: It produces the hormones that regulate the body's metabolism and keep them in balance. Thyroid hormones direct many of the body's processes.

An underactive thyroid does not produce enough hormones. This condition is also referred to as hypothyroidism. It slows down the metabolism, which may cause fatigue, lethargy, or constipation, but these kinds of symptoms can also have a number of other causes. An underactive thyroid can only be diagnosed by examining the level of thyroid hormones in the blood.

Chronic inflammation of the thyroid gland is the most common cause of an underactive thyroid... Read more about Hypothyroidism

What works? Research summarized

Evidence reviews

Chinese herbal medicines for hypothyroidism

Hypothyroidism, also known as underactive or low thyroid, is a condition in which the thyroid gland does not produce sufficient amounts of thyroid hormones which are important for many functions of the body (metabolism). In adults hypothyroidism may cause fatigue and sluggishness, increased sensitivity to cold, constipation, pale and dry skin, brittle fingernails and hair, a puffy face, hoarse voice, unexplained weight gain, muscle aches, tenderness, stiffness and weakness, pain, stiffness or swelling in the joints, heavier than normal menstrual periods, and depression. Hypothyroidism in infants and teenagers may result in poor growth and mental development as well as delayed development of permanent teeth and puberty.

Thyroid hormone replacement for subclinical hypothyroidism

Subclinical hypothyroidism is a condition where some laboratory findings point at a thyroid gland not working properly. Patients with subclinical hypothyroidism may have vague, non‐specific symptoms of actual hypothyroidism (for example dry skin, cold skin or feeling colder, constipation, slower thinking, poor memory) but these thyroid‐related symptoms are not specific, that is why the diagnosis is based on test results. The fundamental question regarding people with subclinical hypothyroidism is whether they should be treated with thyroid hormones. To answer this question twelve studies of six to 14 months duration involving 350 people were analysed. Thyroid hormone therapy for subclinical hypothyroidism did not result in improved survival or decreased cardiovascular morbidity (for example less heart attacks or strokes). Data on health‐related quality of life and symptoms did not demonstrate significant differences between placebo and thyroid hormone therapy. Some evidence indicated that thyroid hormone had some effects on blood lipids and technical measurements of heart function. Adverse effects were inadequately addressed in most of the included studies and have to be urgently investigated in future studies, especially in older patients.

High versus low dose of initial thyroid hormone replacement for congenital hypothyroidism

Congenital hypothyroidism is a condition that affects infants from birth and results from a missing or abnormally developed thyroid gland, abnormal production of thyroid hormones or a failure of the pituitary gland to stimulate thyroid hormone production. It affects approximately 1 in 3000 to 4000 newborn infants and early diagnosis and treatment is very important to achieve a good outcome.Treatment of congenital hypothyroidism consists of a daily dose of thyroid hormone (thyroxine). However, the initial dose of thyroxine required to improve outcomes for infants with this condition is unclear and has been the subject of several studies. Some studies have suggested that when infants with congenital hypothyroidism are treated with a higher dose of thyroxine compared with the standard dose, this results in earlier normalisation of the their thyroid hormones and leads to better developmental outcome and intelligence.

See all (140)

Summaries for consumers

Chinese herbal medicines for hypothyroidism

Hypothyroidism, also known as underactive or low thyroid, is a condition in which the thyroid gland does not produce sufficient amounts of thyroid hormones which are important for many functions of the body (metabolism). In adults hypothyroidism may cause fatigue and sluggishness, increased sensitivity to cold, constipation, pale and dry skin, brittle fingernails and hair, a puffy face, hoarse voice, unexplained weight gain, muscle aches, tenderness, stiffness and weakness, pain, stiffness or swelling in the joints, heavier than normal menstrual periods, and depression. Hypothyroidism in infants and teenagers may result in poor growth and mental development as well as delayed development of permanent teeth and puberty.

Thyroid hormone replacement for subclinical hypothyroidism

Subclinical hypothyroidism is a condition where some laboratory findings point at a thyroid gland not working properly. Patients with subclinical hypothyroidism may have vague, non‐specific symptoms of actual hypothyroidism (for example dry skin, cold skin or feeling colder, constipation, slower thinking, poor memory) but these thyroid‐related symptoms are not specific, that is why the diagnosis is based on test results. The fundamental question regarding people with subclinical hypothyroidism is whether they should be treated with thyroid hormones. To answer this question twelve studies of six to 14 months duration involving 350 people were analysed. Thyroid hormone therapy for subclinical hypothyroidism did not result in improved survival or decreased cardiovascular morbidity (for example less heart attacks or strokes). Data on health‐related quality of life and symptoms did not demonstrate significant differences between placebo and thyroid hormone therapy. Some evidence indicated that thyroid hormone had some effects on blood lipids and technical measurements of heart function. Adverse effects were inadequately addressed in most of the included studies and have to be urgently investigated in future studies, especially in older patients.

High versus low dose of initial thyroid hormone replacement for congenital hypothyroidism

Congenital hypothyroidism is a condition that affects infants from birth and results from a missing or abnormally developed thyroid gland, abnormal production of thyroid hormones or a failure of the pituitary gland to stimulate thyroid hormone production. It affects approximately 1 in 3000 to 4000 newborn infants and early diagnosis and treatment is very important to achieve a good outcome.Treatment of congenital hypothyroidism consists of a daily dose of thyroid hormone (thyroxine). However, the initial dose of thyroxine required to improve outcomes for infants with this condition is unclear and has been the subject of several studies. Some studies have suggested that when infants with congenital hypothyroidism are treated with a higher dose of thyroxine compared with the standard dose, this results in earlier normalisation of the their thyroid hormones and leads to better developmental outcome and intelligence.

See all (27)

Terms to know

Hashimoto's Disease
An autoimmune condition of the thyroid gland (a gland located beneath the larynx).
Metabolism
The chemical changes that take place in a cell or an organism. These changes make energy and the materials cells and organisms need to grow, reproduce, and stay healthy. Metabolism also helps get rid of toxic substances.
Thyroid Gland
A gland located beneath the larynx (voice box) that makes thyroid hormone and calcitonin. The thyroid helps regulate growth and metabolism. Also called thyroid gland.
Thyroid Hormones
A hormone that affects heart rate, blood pressure, body temperature, and weight. Thyroid hormone is made by the thyroid gland and can also be made in the laboratory.
Thyroid-Stimulating Hormone (TSH)
A hormone produced by the pituitary gland. TSH stimulates the release of thyroid hormone.
Thyroiditis
Inflammation of the thyroid gland.

More about Hypothyroidism

Photo of an adult woman

Also called: Underactive thyroid, Thyroid deficiency, Thyroid insufficiency

See Also: Hyperthyroidism

Other terms to know: See all 6
Hashimoto's Disease, Metabolism, Thyroid Gland

Related articles:
Thyroid Function Tests

Keep up with systematic reviews on Hypothyroidism:

Create RSS

PubMed Health Blog...

read all...