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

About Hypothyroidism

Hypothyroidism is a disorder that occurs when the thyroid gland does not make enough thyroid hormone to meet the body's needs. Thyroid hormone regulates metabolism-the way the body uses energy-and affects nearly every organ in the body. Without enough thyroid hormone, many of the body's functions slow down. About 4.6 percent of the U.S. population age 12 and older has hypothyroidism.

What is the thyroid?

The thyroid is a 2-inch-long, butterfly-shaped gland weighing less than 1 ounce. Located in the front of the neck below the larynx, or voice box, it has two lobes, one on each side of the windpipe. The thyroid is one of the glands that make up the endocrine system. The glands of the endocrine system produce and store hormones and release them into the bloodstream. The hormones then travel through the body and direct the activity of the body's cells... NIH - National Institute of Diabetes and Digestive and Kidney Diseases

What works? Research summarized

Evidence reviews

Subclinical hypothyroidism and the risk of coronary heart diesase and mortality

CONTEXT: Data regarding the association between subclinical hypothyroidism and cardiovascular disease outcomes are conflicting among large prospective cohort studies. This might reflect differences in participants' age, sex, thyroid-stimulating hormone (TSH) levels, or preexisting cardiovascular disease.

Hypothyroidism (primary)

INTRODUCTION: Hypothyroidism is six times more common in women, affecting up to 40 in 10,000 each year (compared with 6/10,000 men).

[Should depressive symptoms in patients with subclinical hypothyroidism be treated with thyroid hormone?]

BACKGROUND: Although there are theoretical grounds for using hormone therapy to treat depressive symptoms in patients with hypothyroidism, the clinical evidence for this is unclear. objective To investigate the efficacy of treating depression with thyroid hormone in a population with subclinical hypothyroidism.

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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.

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More about Hypothyroidism

Photo of an adult woman

Also called: Underactive thyroid, Thyroid deficiency, Thyroid insufficiency

Other terms to know:
Metabolism, Thyroid Hormones, Thyroid-Stimulating Hormone (TSH)

Related articles:
Understanding Thyroid Gland Tests

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