Hashimoto's thyroiditis
Encyclopedia
Hashimoto's thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disease
Autoimmune disease
Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to...

 in which the thyroid gland is gradually destroyed by a variety of cell- and antibody-mediated immune processes. It was the first disease to be recognized as an autoimmune disease. It was first described by the Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese specialist Hashimoto Hakaru
Hashimoto Hakaru
was a Japanese medical scientist of the Meiji period and Taishō period.He was born on May 5, 1881, in the village of Midau, Nishitsuge, in Mie Prefecture. He graduated from Kyushu University medical school in 1907...

 in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 in 1912.

Signs and symptoms

Hashimoto's thyroiditis very often results in hypothyroidism
Hypothyroidism
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...

 with bouts of hyperthyroidism
Hyperthyroidism
Hyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...

.

Physiologically, antibodies
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...

 against thyroid peroxidase
Thyroid peroxidase
Thyroid peroxidase or thyroperoxidase is an enzyme expressed mainly in the thyroid that liberates iodine for addition onto tyrosine residues on thyroglobulin for the production of thyroxine or triiodothyronine , thyroid hormones. In humans, thyroperoxidase is encoded by the TPO...

 and/or thyroglobulin
Thyroglobulin
Thyroglobulin is a 660 kDa, dimeric protein produced by and used entirely within the thyroid gland. In earlier literature, Tg was referred to as colloid....

 cause gradual destruction of follicles in the thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...

 gland. Accordingly, the disease can be detected clinically by looking for these antibodies in the blood. It is also characterized by invasion of the thyroid tissue by leukocytes, mainly T-lymphocytes. It is associated with non-Hodgkin lymphoma
Non-Hodgkin lymphoma
The non-Hodgkin lymphomas are a diverse group of blood cancers that include any kind of lymphoma except Hodgkin's lymphomas. Types of NHL vary significantly in their severity, from indolent to very aggressive....

.

Symptoms of Hashimoto's thyroiditis include Myxedematous psychosis
Myxedematous psychosis
Myxedema psychosis, more colloquially known as myxedema madness, is a relatively uncommon consequence of hypothyroidism, such as in Hashimoto's thyroiditis or in patients who have had the thyroid surgically removed and are not taking thyroxine...

, weight gain, depression
Depression (mood)
Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and physical well-being. Depressed people may feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, or restless...

, mania
Mania
Mania, the presence of which is a criterion for certain psychiatric diagnoses, is a state of abnormally elevated or irritable mood, arousal, and/ or energy levels. In a sense, it is the opposite of depression...

, sensitivity to heat and cold, paresthesia
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...

, fatigue, panic attacks, bradycardia
Bradycardia
Bradycardia , in the context of adult medicine, is the resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. It may cause cardiac arrest in some patients, because those with bradycardia may not be pumping enough oxygen to their heart...

, tachycardia
Tachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...

, high cholesterol, reactive hypoglycemia
Reactive hypoglycemia
Reactive hypoglycemia, or postprandial hypoglycemia, is a medical term describing recurrent episodes of symptomatic hypoglycemia occurring within 4 hours after a high carbohydrate meal in people who do not have diabetes...

, constipation, migraines, muscle weakness, cramps, memory loss, infertility, and hair loss.

The thyroid gland may become firm, large, and lobulated in Hashimoto's thyroiditis, but changes in the thyroid can also be nonpalpable.. Enlargement of the thyroid is due to lymphocytic infiltration
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...

 and fibrosis
Fibrosis
Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process. This is as opposed to formation of fibrous tissue as a normal constituent of an organ or tissue...

 rather than tissue hypertrophy
Hypertrophy
Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It should be distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number...

.

Diagnosis

Hashimoto's thyroiditis is often misdiagnosed as depression, cyclothymia
Cyclothymia
Cyclothymia is a mood and mental disorder in the bipolar spectrum that causes both hypomanic and depressive episodes. It is defined medically within the bipolar spectrum and consists of recurrent disturbances between sudden hypomania and dysthymic episodes. The diagnosis of cyclothymic disorder is...

, PMS, chronic fatigue syndrome
Chronic fatigue syndrome
Chronic fatigue syndrome is the most common name used to designate a significantly debilitating medical disorder or group of disorders generally defined by persistent fatigue accompanied by other specific symptoms for a minimum of six months, not due to ongoing exertion, not substantially...

, fibromyalgia
Fibromyalgia
Fibromyalgia is a medical disorder characterized by chronic widespread pain and allodynia, a heightened and painful response to pressure. It is an example of a diagnosis of exclusion...

 and, less frequently, as ED or an anxiety disorder
Anxiety disorder
Anxiety disorder is a blanket term covering several different forms of abnormal and pathological fear and anxiety. Conditions now considered anxiety disorders only came under the aegis of psychiatry at the end of the 19th century. Gelder, Mayou & Geddes explains that anxiety disorders are...

. Testing for thyroid-stimulating hormone
Thyroid-stimulating hormone
Thyrotrophin-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland, which regulates the endocrine function of the thyroid gland.- Physiology :...

 (TSH), Free T3, Free T4, and the anti-thyroglobulin antibodies (anti-Tg), anti-thyroid peroxidase antibodies (anti-TPO) and anti-microsomal antibodies can help obtain an accurate diagnosis.

Hashimoto's when presenting as mania is known as Prasad's syndrome after Ashok Prasad, the psychiatrist who first described it.

Risk factors:
A family history of thyroid disorders is common, with the HLA-DR
HLA-DR antigens
HLA-DR is a MHC class II cell surface receptor encoded by the human leukocyte antigen complex on chromosome 6 region 6p21.31. The complex of HLA-DR and its ligand, a peptide of 9 amino acids in length or longer, constitutes a ligand for the T-cell receptor...

5
gene most strongly implicated conferring a relative risk
Relative risk
In statistics and mathematical epidemiology, relative risk is the risk of an event relative to exposure. Relative risk is a ratio of the probability of the event occurring in the exposed group versus a non-exposed group....

 of 3 in the UK. In addition Hashimoto's thyroiditis may be associated with CTLA-4
CTLA-4
CTLA4 also known as CD152 is a protein that plays an important regulatory role in the immune system...

gene since the CTLA-4 antigen acts as an inhibitor to T-Cell activation only if the red blood cells have an RH factor of negative 3.25.

Preventable environmental factors, including high iodine intake, selenium deficiency, and pollutants such as tobacco smoke, as well as infectious diseases and certain drugs, have been implicated in the development of autoimmune thyroid disease in genetically predisposed individuals. The genes implicated vary in different ethnic groups and the incidence is increased in patients with chromosomal disorders, including Turner
Turner syndrome
Turner syndrome or Ullrich-Turner syndrome encompasses several conditions in human females, of which monosomy X is most common. It is a chromosomal abnormality in which all or part of one of the sex chromosomes is absent...

, Down's
Down syndrome
Down syndrome, or Down's syndrome, trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British physician who described the syndrome in 1866. The condition was clinically described earlier in the 19th...

, and Klinefelter's syndrome
Klinefelter's syndrome
Klinefelter syndrome, 46/47, XXY, or XXY syndrome is a condition in which human males have an extra X chromosome. While females have an XX chromosomal makeup, and males an XY, affected individuals have at least two X chromosomes and at least one Y chromosome...

s usually associated with autoantibodies against thyroglobulin and thyroperoxidase.

The underlying specifics of the immune system destruction of thyroid cells is not clearly understood.
Various autoantibodies may be present against thyroid peroxidase
Thyroid peroxidase
Thyroid peroxidase or thyroperoxidase is an enzyme expressed mainly in the thyroid that liberates iodine for addition onto tyrosine residues on thyroglobulin for the production of thyroxine or triiodothyronine , thyroid hormones. In humans, thyroperoxidase is encoded by the TPO...

, thyroglobulin
Thyroglobulin
Thyroglobulin is a 660 kDa, dimeric protein produced by and used entirely within the thyroid gland. In earlier literature, Tg was referred to as colloid....

 and TSH receptors, although a small percentage of patients may have none of these antibodies present. A percentage of the population may also have these antibodies without developing Hashimoto's thyroiditis.

Treatment

Hypothyroidism
Hypothyroidism
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...

 caused by Hashimoto's Thyroiditis is treated with thyroid hormone replacement agents such as levothyroxine
Levothyroxine
Levothyroxine, also L-thyroxine, synthetic T4, or 3,5,3',5'-tetraiodo-L-thyronine, is a synthetic form of thyroxine , used as a hormone replacement for patients with thyroid problems. The natural hormone is chemically in the chiral L-form, as is the pharmaceutical agent...

 or desiccated thyroid extract
Desiccated thyroid extract
Desiccated thyroid or thyroid extract, refers to porcine thyroid glands, dried and powdered for therapeutic use. As an animal product, it is not suitable for use by vegetarians. Some religious dietary laws object to the use of pork products as well, although exceptions are sometimes made for...

. A tablet taken once a day generally keeps the thyroid hormone levels normal. In most cases, the treatment needs to be taken for the rest of the patient's life. In the event that hypothyroidism is caused by Hashimoto's Thyroiditis, it is recommended that the TSH levels be kept under 3.0. As long as the patient's thyroid is active, the body will continue to attack it, and this can wreak havoc on the patient's TSH levels and symptoms.

Prognosis

If untreated for an extended period, Hashimoto's thyroiditis may lead to muscle failure, including possible heart failure. An extremely rare condition associated with the thyroiditis is Hashimoto's encephalopathy
Hashimoto's encephalopathy
Hashimoto's Encephalopathy is a very rare condition associated with Hashimoto's thyroiditis. It was first described in 1966. It is classified as a neuroendocrine disorder....

.

A rare association is with lymphoma of the thyroid gland.

Hashimoto's thyroiditis can disrupt growth in children and adolescents and therefore requires close growth monitoring. Growth hormone therapy may be required if the patient's stature is extreme enough.

Epidemiology

This disorder is believed to be the most common cause of primary hypothyroidism
Hypothyroidism
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...

 in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. An average of 1 to 1.5 in a 1000 people have this disease. It occurs far more often in women than in men (between 10:1 and 20:1), and is most prevalent between 45 and 65 years of age.

In European countries, an atrophic form of autoimmune thyroiditis (Ord's thyroiditis
Ord's thyroiditis
Ord's thyroiditis is a common form of thyroiditis, an autoimmune disease where the body's own antibodies fight the cells of the thyroid. It is named after the physician, William Miller Ord, who first described it in 1877 and again in 1888...

) is more common than Hashimoto's thyroiditis.

History

Also known as Hashimoto's disease, Hashimoto's thyroiditis is named after the Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese physician Hashimoto Hakaru
Hashimoto Hakaru
was a Japanese medical scientist of the Meiji period and Taishō period.He was born on May 5, 1881, in the village of Midau, Nishitsuge, in Mie Prefecture. He graduated from Kyushu University medical school in 1907...

 (1881−1934) of the medical school at Kyushu University
Kyushu University
Kyushu University is one of the most prestigious universities in Japan. It can be seen in the several rankings such as shown below.-General Rankings:The university has been ranked 8th in 2010 and 2009 in the ranking "Truly Strong Universities" by Toyo Keizai...

, who first described the symptoms in 1912 in a German publication.

External links

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