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Hypothyroidism

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

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(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.

Screening and Treatment of Subclinical Hypothyroidism or Hyperthyroidism [Internet]

This report focused on four questions:

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.

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Summaries for consumers

Underactive thyroid: Deciding whether to treat subclinical hypothyroidism

Subclinical (latent) hypothyroidism means that the thyroid gland is still producing enough thyroid hormones. But some blood values may suggest the early stages of a hormone deficiency. Experts do not agree on whether subclinical hypothyroidism should be treated. It is not clear in which cases treatment would have advantages.If you already have noticeable (“overt” or “manifest”) hypothyroidism, the thyroid is no longer producing enough thyroid hormones. Thyroxine is the most important of the thyroid hormones. It helps regulate many of the body’s functions to balance your metabolism. Too little thyroxine can cause a number of different health problems. The symptoms range from cold hands to physical weakness, slower mental processes and depression. An underactive thyroid (hypothyroidism) is treated with hormone tablets that are taken once daily. These tablets act to replace the thyroxine that is not being produced. This can usually make the symptoms disappear completely.Subclinical hypothyroidism goes unnoticed. Only the body’s levels of TSH (“thyroid-stimulating hormone”) are too high. The thyroid is still producing enough thyroid hormones. The hormone TSH is produced in the pituitary gland and acts as a trigger for the thyroid to start producing the thyroid hormones. TSH levels that are just a little too high may be the first sign of the early stages of hypothyroidism: The pituitary gland responds to lower levels of thyroid hormones by increasing TSH production to activate the thyroid. It is also possible that TSH reaches higher levels only temporarily, for example after intense physical activity.It is estimated that about 5 out of 100 people have subclinical hypothyroidism. Slightly elevated TSH levels are usually detected by accident during a routine examination. But taken on their own they do not pose any health risk – often the effect is just temporary. Experts do not fully agree on how to decide in which cases subclinical hypothyroidism should be treated.

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.

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Terms to know

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.

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 4
Metabolism, Thyroid Gland, Thyroid Hormones

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