HyperthyroidismOveractive thyroid

Last reviewed: April 19, 2010.

Hyperthyroidism is a condition in which the thyroid gland makes too much thyroid hormone. The condition is often referred to as an "overactive thyroid."Causes, incidence, and risk factorsThe thyroid gland is an important organ of the endocrine system. It is located in the front of the neck just below the voice box. The gland produces the hormones thyroxine (T4) and triiodothyronine (T3), which control the way every cell in the body uses energy. This process is called your metabolism.Hyperthyroidism occurs when the thyroid releases too much of its hormones over a short (acute) or long (chronic) period of time. Many diseases and conditions can cause this problem, including:

Getting too much iodine

Graves disease  (accounts for most cases of hyperthyroidism) Inflammation (thyroiditis) of the thyroid due to viral infections or other causes Noncancerous growths of the thyroid gland or pituitary gland Taking large amounts of thyroid hormone Tumors of the testes or ovaries

Related topics:

Factitious hyperthyroidism Hypothyroidism Painless (silent) thyroiditis

Symptoms

Difficulty concentrating

Fatigue

Frequent bowel movements

Goiter  (visibly enlarged thyroid gland) or thyroid nodules Heat intolerance Increased appetite Increased sweating

Irregular menstrual periods in women

Nervousness

Restlessness Weight loss  (rarely, weight gain)

Other symptoms that can occur with this disease:

Breast development in men

Clammy skin

Diarrhea

Hair loss Hand tremor Weakness High blood pressure

Itching - overall

Lack of menstrual periods in women

Nausea and vomiting

Pounding, rapid, or irregular pulse

Protruding eyes  (exophthalmos) Rapid, forceful, or irregular heartbeat (palpitations)

Skin blushing or flushing

Sleeping difficulty Signs and testsPhysical examination may reveal thyroid enlargement, tremor, hyperactive reflexes, or an increased heart rate. Systolic blood pressure (the first number in a blood pressure reading) may be high.Subclinical hyperthyroidism is a mild form of hyperthyroidism that is diagnosed by abnormal blood levels of thyroid hormones, often in the absence of any symptoms.Blood tests are also done to measure levels of thyroid hormones.

TSH  (thyroid stimulating hormone) level is usually low

T3 and free T4 levels are usually high

This disease may also affect the results of the following tests:

Cholesterol test

Glucose test Radioactive iodine uptake T3RU Triglycerides Vitamin B12  (in rare cases)

Treatment

How the condition is treated depends on the cause and the severity of symptoms. Hyperthyroidism is usually treated with one or more of the following:

Antithyroid medications

Radioactive iodine (which destroys the thyroid and stops the excess production of hormones)

Surgery to remove the thyroidIf the thyroid must be removed with surgery or destroyed with radiation, you must take thyroid hormone replacement pills for the rest of your life.

Beta-blockers such as propranolol are used to treat some of the symptoms, including rapid heart rate, sweating, and anxiety until the hyperthyroidism can be controlled.

Expectations (prognosis)

Hyperthyroidism is generally treatable and only rarely is life threatening. Some of its causes may go away without treatment.

Hyperthyroidism caused by Graves disease usually gets worse over time. It has many complications, some of which are severe and affect quality of life.

ComplicationsThyroid crisis (storm), also called thyrotoxicosis, is a sudden worsening of hyperthyroidism symptoms that may occur with infection or stress. Fever, decreased mental alertness, and abdominal pain may occur. Immediate hospitalization is needed.

Other complications related to hyperthyroidism include:

Heart-related complications including:

Rapid heart rate Congestive heart failure Atrial fibrillation

Increased risk for osteoporosis, if hyperthyroidism is present for a long time

Surgery-related complications, including:

Scarring of the neck

Hoarseness due to nerve damage to the voice box

Low calcium level due to damage to the parathyroid glands (located near the thyroid gland)

Treatments for hypothyroidism, such as radioactive iodine, surgery, and medications to replace thyroid hormones can have complications.

Calling your health care providerCall your health care provider if you have symptoms that could be caused by too much thyroid hormone production. Go to an emergency room or call the local emergency number (such as 911), if you have:

Change in consciousness

Dizziness

Rapid, irregular heartbeat

Call your health care provider if you are being treated for hyperthyroidism and you develop symptoms of underactive thyroid, including:

Depression

Mental and physical sluggishness

Weight gain

Prevention

There are no known ways to prevent hyperthyroidism.

Hyperthyroidism

What is hyperthyroidism?

Hyperthyroidism means overactivity of the thyroid gland, resulting in too much thyroid hormone in the

bloodstream. The oversecretion of thyroid hormones leads to overactivity of the body's metabolism.

Thyroid Gland - Click to Enlarge

What are the symptoms of hyperthyroidism?

The following are the most common symptoms of hyperthyroidism. However, each individual may

experience symptoms differently. Symptoms may include:

Nervousness

Irritability

Increased perspiration

Thinning of the skin

Fine, brittle hair

Weak muscles, especially in the upper arms and thighs

Shaky hands

Fast heartbeat

High blood pressure

Increased bowel movements

Weight loss

Sleeping difficulty

Prominent eyes

Sensitivity to bright light

Confusion

Irregular menstrual cycle

The symptoms of hyperthyroidism may resemble other conditions or medical problems. Always consult

your doctor for a diagnosis.

Types of hyperthyroidism

There are several forms of hyperthyroidism, including:

Graves' disease (diffuse toxic goiter). Graves' disease is most often associated with

hyperthyroidism. Researchers believe Graves' disease is caused by an antibody which stimulates the

thyroid too much. This overstimulation causes the excess production of thyroid hormone. Graves'

disease is categorized as an autoimmune disorder (a dysfunction of the body's immune system). The

disease is most common in young to middle-aged women and tends to run in families.

Symptoms of Graves' disease are identical to hyperthyroidism, with the addition of three other

symptoms. However, each individual may experience symptoms differently. The three additional

symptoms include:

Goiter (enlarged thyroid which may cause a bulge in the neck)

Bulging eyes (exophthalmos)

Thickened skin over the shin area

Toxic nodular goiter (also called multinodular goiter). Hyperthyroidism caused by toxic nodular

goiter is a condition in which one or more nodules of the thyroid becomes overactive. The overactive

nodules actually act as benign thyroid tumors. Symptoms of toxic nodular goiter do not include

bulging eyes or skin problems, as in Graves' disease. The cause of toxic nodular goiter is not known.

Thyroiditis. Thyroiditis causes temporary hyperthyroidism, usually followed with hypothyroidism (an

underactive thyroid). Thyroiditis is an inflammation of the thyroid gland. There are three types of

thyroiditis:

Hashimoto's thyroiditis

Subacute granulomatous thyroiditis

Silent lymphocytic thyroiditis

In addition, if a person takes too many thyroid hormone tablets, hyperthyroidism may occur.

How is hyperthyroidism diagnosed?

In addition to a complete medical history and medical examination, diagnostic procedures for

hyperthyroidism may include:

Measurement of thyroid hormone in the bloodstream

Thyroid ultrasound.  A test to evaluate the thyroid gland for evidence of any nodules. 

Thyroid scan. A test that uses a radioactive substance to create an image of the thyroid.

Treatment for hyperthyroidism

Treatment for hyperthyroidism is very specific for each patient. The goal of treatment is to restore the

thyroid gland to normal function, producing normal levels of thyroid hormone. Specific treatment for

hyperthyroidism will be determined by your doctor based on:

Your age, overall health, and medical history

Type of hyperthyroidism

Extent of the disease

Your tolerance for specific medications, procedures, or therapies

Expectations for the course of the disease

Your opinion or preference

Treatment may include:

Use of antithyroid drugs that help lower the level of thyroid hormones in the blood.

Use of radioactive iodine, in the form of a pill or liquid, which damages thyroid cells so that production

of thyroid hormones is slowed down.

Surgery to remove part of the thyroid (the overactive nodule).

Use of beta-blocking agents, which block the action of thyroid hormone on the body; (These drugs do

not change the levels of thyroid hormone in the blood, but may make the patient feel better.)

--

Facts about hyperthyroidism:

Less than 1 percent of people in the US have hyperthyroidism.

Hyperthyroidism usually occurs between the ages of 30 and 50.

Hyperthyroidism is more common in women than in men.--

Incidence (annual) of Congenital hypothyroidism:

about 1 in 4000 babies

Incidence Rate for Congenital hypothyroidism: approx 1 in 272,000 or 0.00% or 1,000 people in

USA [about data]Extrapolation of Incidence Rate for Congenital hypothyroidism to Countries and

Regions: WARNING! EXTRAPOLATION ONLY. NOT BASED ON COUNTRY-SPECIFIC DATA

SOURCES. The following table attempts to extrapolate the above incidence rate for Congenital

hypothyroidism to the populations of various countries and regions. As discussed above, these

incidence extrapolations for Congenital hypothyroidism are only estimates and may have very limited

relevance to the actual incidence of Congenital hypothyroidism in any region:

Country/Region Extrapolated Incidence Population Estimated Used

Congenital hypothyroidism in North America (Extrapolated Statistics)

USA 1,079 293,655,4051

Canada 119 WARNING!   (Details) 32,507,8742

Mexico 385 WARNING!   (Details) 104,959,5942

Congenital hypothyroidism in Central America (Extrapolated Statistics)

Belize 1 WARNING!   (Details) 272,9452

Guatemala 52 WARNING!   (Details) 14,280,5962

Nicaragua 19 WARNING!   (Details) 5,359,7592

Congenital hypothyroidism in Caribbean (Extrapolated Statistics)

Puerto Rico 14 WARNING!   (Details) 3,897,9602

Congenital hypothyroidism in South America (Extrapolated Statistics)

Brazil 676 WARNING!   (Details) 184,101,1092

Chile 58 WARNING!   (Details) 15,823,9572

Colombia 155 WARNING!   (Details) 42,310,7752

Paraguay 22 WARNING!   (Details) 6,191,3682

Peru 101 WARNING!   (Details) 27,544,3052

Venezuela 91 WARNING!   (Details) 25,017,3872

Congenital hypothyroidism in Northern Europe (Extrapolated Statistics)

Denmark 19 WARNING!   (Details) 5,413,3922

Finland 19 WARNING!   (Details) 5,214,5122

Iceland 1 WARNING!   (Details) 293,9662

Sweden 33 WARNING!   (Details) 8,986,4002

Congenital hypothyroidism in Western Europe (Extrapolated Statistics)

Britain (United Kingdom) 221 WARNING!   (Details) 60,270,708 for UK2

Belgium 38 WARNING!   (Details) 10,348,2762

France 222 WARNING!   (Details) 60,424,2132

Ireland 14 WARNING!   (Details) 3,969,5582

Luxembourg 1 WARNING!   (Details) 462,6902

Monaco 0 WARNING!   (Details) 32,2702

Netherlands (Holland) 59 WARNING!   (Details) 16,318,1992

United Kingdom 221 WARNING!   (Details) 60,270,7082

Wales 10 WARNING!   (Details) 2,918,0002

Congenital hypothyroidism in Central Europe (Extrapolated Statistics)

Austria 30 WARNING!   (Details) 8,174,7622

Czech Republic 4 WARNING!   (Details) 1,0246,1782

Germany 303 WARNING!   (Details) 82,424,6092

Hungary 36 WARNING!   (Details) 10,032,3752

Liechtenstein 0 WARNING!   (Details) 33,4362

Poland 142 WARNING!   (Details) 38,626,3492

Slovakia 19 WARNING!   (Details) 5,423,5672

Slovenia 7 WARNING!   (Details) 2,011,473 2

Switzerland 27 WARNING!   (Details) 7,450,8672

Congenital hypothyroidism in Eastern Europe (Extrapolated Statistics)

Belarus 37 WARNING!   (Details) 10,310,5202

Estonia 4 WARNING!   (Details) 1,341,6642

Latvia 8 WARNING!   (Details) 2,306,3062

Lithuania 13 WARNING!   (Details) 3,607,8992

Russia 529 WARNING!   (Details) 143,974,0592

Ukraine 175 WARNING!   (Details) 47,732,0792

Congenital hypothyroidism in the Southwestern Europe (Extrapolated Statistics)

Azerbaijan 28 WARNING!   (Details) 7,868,3852

Portugal 38 WARNING!   (Details) 10,524,1452

Spain 148 WARNING!   (Details) 40,280,7802

Georgia 17 WARNING!   (Details) 4,693,8922

Congenital hypothyroidism in the Southern Europe (Extrapolated Statistics)

Italy 213 WARNING!   (Details) 58,057,4772

Greece 39 WARNING!   (Details) 10,647,5292

Congenital hypothyroidism in the Southeastern Europe (Extrapolated Statistics)

Albania 13 WARNING!   (Details) 3,544,8082

Bosnia and Herzegovina 1 WARNING!   (Details) 407,6082

Bulgaria 27 WARNING!   (Details) 7,517,9732

Croatia 16 WARNING!   (Details) 4,496,8692

Macedonia 7 WARNING!   (Details) 2,040,0852

Romania 82 WARNING!   (Details) 22,355,5512

Serbia and Montenegro 39 WARNING!   (Details) 10,825,9002

Congenital hypothyroidism in Northern Asia (Extrapolated Statistics)

Mongolia 10 WARNING!   (Details) 2,751,3142

Congenital hypothyroidism in Central Asia (Extrapolated Statistics)

Kazakhstan 55 WARNING!   (Details) 15,143,7042

Tajikistan 25 WARNING!   (Details) 7,011,556 2

Uzbekistan 97 WARNING!   (Details) 26,410,4162

Congenital hypothyroidism in Eastern Asia (Extrapolated Statistics)

China 4,775 WARNING!   (Details) 1,298,847,6242

Hong Kong s.a.r. 25 WARNING!   (Details) 6,855,1252

Japan 468 WARNING!   (Details) 127,333,0022

Macau s.a.r. 1 WARNING!   (Details) 445,2862

North Korea 83 WARNING!   (Details) 22,697,5532

South Korea 177 WARNING!   (Details) 48,233,7602

Taiwan 83 WARNING!   (Details) 22,749,8382

Congenital hypothyroidism in Southwestern Asia (Extrapolated Statistics)

Turkey 253 WARNING!   (Details) 68,893,9182

Congenital hypothyroidism in Southern Asia (Extrapolated Statistics)

Afghanistan 104 WARNING!   (Details) 28,513,6772

Bangladesh 519 WARNING!   (Details) 141,340,4762

Bhutan 8 WARNING!   (Details) 2,185,5692

India 3,915 WARNING!   (Details) 1,065,070,6072

Pakistan 585 WARNING!   (Details) 159,196,3362

Sri Lanka 73 WARNING!   (Details) 19,905,1652

Congenital hypothyroidism in Southeastern Asia (Extrapolated Statistics)

East Timor 3 WARNING!   (Details) 1,019,2522

Indonesia 876 WARNING!   (Details) 238,452,9522

Laos 22 WARNING!   (Details) 6,068,1172

Malaysia 86 WARNING!   (Details) 23,522,4822

Philippines 317 WARNING!   (Details) 86,241,6972

Singapore 16 WARNING!   (Details) 4,353,8932

Thailand 238 WARNING!   (Details) 64,865,5232

Vietnam 303 WARNING!   (Details) 82,662,8002

Congenital hypothyroidism in the Middle East (Extrapolated Statistics)

Gaza strip 4 WARNING!   (Details) 1,324,9912

Iran 248 WARNING!   (Details) 67,503,2052

Iraq 93 WARNING!   (Details) 25,374,6912

Israel 22 WARNING!   (Details) 6,199,0082

Jordan 20 WARNING!   (Details) 5,611,2022

Kuwait 8 WARNING!   (Details) 2,257,5492

Lebanon 13 WARNING!   (Details) 3,777,2182

Saudi Arabia 94 WARNING!   (Details) 25,795,9382

Syria 66 WARNING!   (Details) 18,016,8742

United Arab Emirates 9 WARNING!   (Details) 2,523,9152

West Bank 8 WARNING!   (Details) 2,311,2042

Yemen 73 WARNING!   (Details) 20,024,8672

Congenital hypothyroidism in Northern Africa (Extrapolated Statistics)

Egypt 279 WARNING!   (Details) 76,117,4212

Libya 20 WARNING!   (Details) 5,631,5852

Sudan 143 WARNING!   (Details) 39,148,1622

Congenital hypothyroidism in Western Africa (Extrapolated Statistics)

Congo Brazzaville 11 WARNING!   (Details) 2,998,0402

Ghana 76 WARNING!   (Details) 20,757,0322

Liberia 12 WARNING!   (Details) 3,390,6352

Niger 41 WARNING!   (Details) 11,360,5382

Nigeria 65 WARNING!   (Details) 12,5750,3562

Senegal 39 WARNING!   (Details) 10,852,1472

Sierra leone 21 WARNING!   (Details) 5,883,8892

Congenital hypothyroidism in Central Africa (Extrapolated Statistics)

Central African Republic 13 WARNING!   (Details) 3,742,4822

Chad 35 WARNING!   (Details) 9,538,5442

Congo kinshasa 214 WARNING!   (Details) 58,317,0302

Rwanda 30 WARNING!   (Details) 8,238,6732

Congenital hypothyroidism in Eastern Africa (Extrapolated Statistics)

Ethiopia 262 WARNING!   (Details) 71,336,5712

Kenya 121 WARNING!   (Details) 32,982,1092

Somalia 30 WARNING!   (Details) 8,304,6012

Tanzania 132 WARNING!   (Details) 36,070,7992

Uganda 97 WARNING!   (Details) 26,390,2582

Congenital hypothyroidism in Southern Africa (Extrapolated Statistics)

Angola 40 WARNING!   (Details) 10,978,5522

Botswana 6 WARNING!   (Details) 1,639,2312

South Africa 163 WARNING!   (Details) 44,448,4702

Swaziland 4 WARNING!   (Details) 1,169,2412

Zambia 40 WARNING!   (Details) 11,025,6902

Zimbabwe 13 WARNING!   (Details) 1,2671,8602

Congenital hypothyroidism in Oceania (Extrapolated Statistics)

Australia 73 WARNING!   (Details) 19,913,1442

New Zealand 14 WARNING!   (Details) 3,993,8172

Papua New Guinea 19 WARNING!   (Details) 5,420,2802

About extrapolations of prevalence and incidence statistics for Congenital hypothyroidism:

WARNING! EXTRAPOLATED STATISTICS ONLY! Not based on data sources from individual

countries. These statistics are calculated extrapolations of various prevalence or incidence rates against

the populations of a particular country or region. The statistics used for prevalence/incidence of

Congenital hypothyroidism are typically based on US, UK, Canadian or Australian prevalence or

incidence statistics, which are then extrapolated using only the population of the other country. This

extrapolation calculation is automated and does not take into account any genetic, cultural,

environmental, social, racial or other differences across the various countries and regions for which the

extrapolated Congenital hypothyroidism statistics below refer to. The extrapolation does not use data

sources or statistics about any country other than its population. As such, these extrapolations may

be highly inaccurate (especially for developing or third-world countries) and only give a general

indication (or even a meaningless indication) as to the actual prevalence or incidence of Congenital

hypothyroidism in that region. These statistics are presented only in the hope that they may be

interesting to some people.

About prevalence and incidence statistics in general for Congenital hypothyroidism:

The word 'prevalence' of Congenital hypothyroidism usually means the estimated population of people who are managing Congenital hypothyroidism at any given time (i.e. people with Congenital hypothyroidism). The term 'incidence' of Congenital hypothyroidism means the annual diagnosis rate, or the number of new cases of Congenital hypothyroidism diagnosed each year (i.e. getting Congenital hypothyroidism). Hence, these two statistics types can differ: a short disease like flucan have high annual incidence but low prevalence, but a life-long disease like diabetes has a low annual incidence but

hANATOMY AND PHYSIOLOGY OF THE THYROID GLAND

A normal adult thyroid gland usually weighs 10 to 20 g. It receives its nourishment from bilateral superior and inferior thyroid arteries and a small artery called thyroid ima.

The thyroid gland secretes two thyroid hormones (THs). Thyroxine (T4) represents 90% of thyroid hormone production, whereas triiodothyronine (T3) comprises 10%. Peripheral tissues convert T4 to T3 and most T3 is derived from T4. TH secretion is regulated by the hypothalamus-pituitary-thyroid axis through the actions of thyroid-releasing hormone (TRH) and thyroid-stimulating hormone (TSH).

Thyroid hormones are transported in serum bound to carrier proteins and only 0.03% to 0.04% of T4 and 0.3% to 0.4% of T3 exist as a free hormone. Thyroid-binding globulin (TBG) is the main carrier, accounting for 75% of bound T4 and all bound T3. Thyroxine-binding prealbumin (TBPA) accounts for 15% of T4binding, and albumin …

-igh prevalence. For more information see about prevalence and incidence statistics.