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Encyclopedia > Congenital hypothyroidism
Congenital hypothyroidism
Classifications and external resources
ICD-10 E00, E03.0, E03.1
ICD-9 243

Congenital hypothyroidism (CHT) is a condition of thyroid hormone deficiency present at birth. Approximately 1 in 4000 newborn infants has a severe deficiency of thyroid function, while even more have mild or partial degrees. If untreated for several months after birth, severe congenital hypothyroidism can lead to growth failure and permanent mental retardation. Treatment consists of a daily dose of thyroid hormone (thyroxine) by mouth. Because the treatment is simple, effective, and inexpensive, nearly all of the developed world practices newborn screening to detect and treat congenital hypothyroidism in the first weeks of life. The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... Growth failure is a medical term for a pattern of a childs growth which is poorer than normal for age, sex, stage of maturation, and genetic height expectation. ... Mental retardation (also called mental handicap[1] and, as defined by the UK Mental Health Act 1983, mental impairment and severe mental impairment[2]) is a term for a pattern of persistently slow learning of basic motor and language skills (milestones) during childhood, and a significantly below-normal global intellectual... The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. ... Newborn screening is the process of testing newborn babies for treatable genetic, endocrinologic, metabolic and hematologic diseases. ...

Contents

Causes

Around the world, the most common cause of congenital hypothyroidism is iodine deficiency, but in most of the developed world and areas of adequate environmental iodine, cases are due to a combination of known and unknown causes. Most commonly there is a defect of development of the thyroid gland itself, resulting in an absent (athyreosis) or underdeveloped (hypoplastic) gland. A hypoplastic gland may develop higher in the neck or even in the back of the tongue. A gland in the wrong place is referred to as ectopic, and an ectopic gland at the base or back of the tongue is a lingual thyroid. Some of these cases of developmentally abnormal glands result from genetic defects, and some are "sporadic," with no identifiable cause. General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ... A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ...


Congenital hypothyroidism can also occur due to genetic defects of thyroxine or triiodothyronine synthesis within a structurally normal gland. Among specific defects are thyrotropin (TSH) resistance, iodine trapping defect, organification defect, thyroglobulin, and iodotyrosine deiodinase deficiency. In a small proportion of cases of congenital hypothyroidism, the defect is due to a deficiency of thyroid stimulating hormone, either isolated or as part of congenital hypopituitarism. The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. ... Thyroid-stimulating hormone (also known as TSH or thyrotropin) is a hormone produced by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland. ... Thyroglobulin is a protein secreted by the thyroid gland. ... Hypopituitarism is a medical term describing deficiency (hypo) of one or more hormones of the pituitary gland. ...


In some instances, hypothyroidism detected by screening may be transient. The most common cause of this is the presence of maternal antibodies which temporarily impair thyroid function for several weeks. Schematic of antibody binding to an antigen An antibody or immunoglobulin is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ...


Cretinism is an old term for the state of mental and physical retardation resulting from untreated congenital hypothyroidism, usually due to iodine deficiency from birth because of low iodine levels in the soil and local food sources. The term, like so many other 19th century medical terms, acquired pejorative connotations as it became used in lay speech. It is now rarely used by physicians. Cretinism (most likely from the Latin Christiānum, Christian) is a condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormones (hypothyroidism). ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ...


Diagnostic evaluation

In the developed world, nearly all cases of congenital hypothyroidism are detected by the newborn screening program. These are based on measurement of TSH or thyroxine (T4) on the second or third day of life. If the TSH is high, or the T4 low, the infant's doctor and parents are called and a referral to a pediatric endocrinologist is recommended to confirm the diagnosis and initiate treatment. Often a technetium thyroid scan is performed to detect a structurally abnormal gland. Pediatric endocrinology is a medical subspecialty dealing with variations of physical growth and sexual development in childhood, as well as diabetes and other disorders of the endocrine glands. ... General Name, Symbol, Number technetium, Tc, 43 Chemical series transition metals Group, Period, Block 7, 5, d Appearance silvery gray metal Atomic mass [98](0) g/mol Electron configuration [Kr] 4d5 5s2 Electrons per shell 2, 8, 18, 13, 2 Physical properties Phase solid Density (near r. ...


Treatment

The goal of newborn screening programs is to detect and start treatment within the first 1-2 weeks of life. Treatment consists of a daily dose of thyroxine, available as a small tablet. The generic name is levothyroxine, and several brands are available. Commonly used brands in North America are Synthroid, Levoxyl, Unithroid, and Levothroid. The tablet is crushed and given to the infant with a small amount of water or milk. The most commonly recommended dose range is 10-15 μg/kg daily, typically 37.5 or 44 μg. The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. ... Levothyroxine, also known as L-thyroxine, synthetic T4 or simply 3,5,3,5-tetraiodo-L-thyronine, is a synthetic form of thyroxine (thyroid hormone). ... Synthroid is the brand name used by Abbott Laboratories for levothyroxine sodium (T4, a synthetic thyroid hormone) product. ... Levothyroxine, also known as L-thyroxine, synthetic T4 or simply 3,5,3,5-tetraiodo-L-thyronine, is a synthetic form of thyroxine (thyroid hormone). ... Levothyroxine, also known as L-thyroxine, synthetic T4 or simply 3,5,3,5-tetraiodo-L-thyronine, is a synthetic form of thyroxine (thyroid hormone). ... The microgram (symbol µg, sometimes mcg) is an SI unit of mass. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ...


Within a few weeks, the T4 and TSH levels are rechecked to confirm that they are being normalized by treatment. As the child grows up, these levels are checked regularly to maintain the right dose. The dose increases as the child grows.


Symptoms

Infants born with congenital hypothyroidism may show no effects, or may display mild effects that often go unrecognized as a problem: excessive sleeping, reduced interest in nursing, poor muscle tone, low or hoarse cry, infrequent bowel movements, exaggerated jaundice, and low body temperature. If fetal deficiency was severe because of complete absence (athyreosis) of the gland, physical features may include a larger anterior fontanel, persistence of a posterior fontanel, an umbilical hernia, and a large tongue (macroglossia). Hypersomnia is an excessive amount of sleepiness, resulting in an inability to stay awake. ... Wean redirects here: see #Weaning. ... Hypotonia is a serious medical condition that entails abnormally-decreased muscle tone, and is almost always found as early as infancy. ... Jaundice, also known as icterus (adjective:Icteric), is yellowing of the skin, sclera (the white of the eyes) and mucous membranes caused by increased levels of bilirubin in the human body. ... Hypothermia is a medical condition in which the victims core body temperature has dropped to significantly below normal and normal metabolism begins to be impaired. ... In human anatomy, a fontanelle (or fontanel) is one of two soft spots on a newborn humans skull. ... A medical term for an unusually enlarged tounge. ...


In the era before newborn screening, less than half of cases of severe hypothyroidism were recognized in the first month of life. As the months proceeded, these infants would grow poorly and be delayed in their development. By several years of age, they would display the recognizable facial and body features of cretinism. Persistence of severe, untreated hypothyroidism resulted in severe mental impairment, with an IQ below 80 in the majority. Most of these children eventually ended up in institutional care. IQ redirects here; for other uses of that term, see IQ (disambiguation). ...


Prognosis

Most children born with congenital hypothyroidism and correctly treated with thyroxine grow and develop normally in all respects. Even most of those with athyreosis and undetectable T4 levels at birth develop with normal intelligence, although as a population academic performance tends to be below that of siblings and mild learning problems occur in some.


Congenital hypothyroidism is the most common preventable cause of mental retardation. Few treatments in the practice of medicine provide as large a benefit for as small an effort. Medicine is the branch of health science and the sector of public life concerned with maintaining or restoring human health through the study, diagnosis, treatment and possible prevention of disease and injury. ...


See also


  Results from FactBites:
 
Congenital hypothyroidism - Genetics Home Reference (755 words)
Congenital hypothyroidism is a condition that affects infants from birth (congenital) and results from a partial or complete loss of thyroid function (hypothyroidism).
Mutations in the DUOX2, PAX8, SLC5A5, TG, TPO, TSHB, and TSHR genes cause congenital hypothyroidism.
Most cases of congenital hypothyroidism are sporadic, which means they occur in people with no history of the disorder in their family.
Congenital hypothyroidism - Wikipedia, the free encyclopedia (836 words)
Congenital hypothyroidism (CHT) is a condition of thyroid hormone deficiency present at birth.
Around the world, the most common cause of congenital hypothyroidism is iodine deficiency, but in most of the developed world and areas of adequate environmental iodine, cases are due to a combination of known and unknown causes.
In a small proportion of cases of congenital hypothyroidism, the defect is due to a deficiency of thyroid stimulating hormone, either isolated or as part of congenital hypopituitarism.
  More results at FactBites »

 
 

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