Subclinical cretinism

Introduction to subclinical cretinism Subclinical cretinism (akectin) is a very light cretin patient caused by iodine deficiency. These people cannot be diagnosed with typical Dick disease, but they are not normal, often with mild mental retardation. The main characteristics affect the quality of the ward population, which constitutes a serious public health problem because the proportion of the disease is far greater than that of Dick disease. In general diseases, especially nutritional deficiencies, there will always be a considerable number of people between patients and normal people. These people are often referred to as marginal patients or subclinical patients. basic knowledge The proportion of illness: 0.02% Susceptible people: no special people Mode of infection: non-infectious Complications: mental retardation

Subclinical cretinism etiology

Causes:

Because of its mild clinical retardation, ykting disease belongs to the mental retardation with structural abnormalities. The so-called structural abnormality means that this mental retardation has certain pathological changes, structural abnormalities and nervous system damage. The pathogenesis of this disease is the same as that of Dick disease. Mild damage caused by mild iodine deficiency or iodine deficiency is the basic link of its disease. It is worth noting that in recent years, the concentration of iodized salt is unstable or unqualified and non- Iodized salt enters the ward, and the correction of iodine deficiency in the population is not complete. Although the thyroid swollen and the gram disease have been basically controlled, the key population, especially the iodine deficiency in pregnant women, is an important cause of acquitine.

Pathogenesis:

The pathogenesis of this disease is the same as that of Dick disease. The pathogenesis of Dick disease may be related to two factors: the lack of thyroid hormone synthesis and the direct independent effect of iodide deficiency.

1. Insufficient synthesis of thyroid hormone: The role of thyroid hormone in physical development (including bone development, sexual development) has been recognized, however, the relationship between thyroid hormone and brain development has been a hot topic in the pathogenesis of Dick disease.

Dobbing pointed out that there are two main periods in the growth phase of the human brain: the first phase is the proliferative phase of nerve cells, which begins about 12 to 18 weeks of gestation and is completed in the middle of pregnancy. The external environmental factors such as radioactive irradiation, mother Infection is extremely sensitive, and the second phase is the most important period of brain development, which is characterized by brain cell differentiation, migration, myelination, dendritic development, sudden triggering, establishment of neural connections and proliferation of glial cells. In the second trimester, its development peaks before and after birth and lasts for a period of time after birth. This period may last until the age of 2 years, and the first 6 months after birth is the most critical moment of postnatal brain development, about 5 /6 brain development is completed after birth, the second phase is extremely sensitive to nutritional factors and hormone deficiency (including hypothyroidism), a large number of animal experiments confirmed that the effect of thyroid hormone on brain development has a certain time, in During this time period, hypothyroidism can cause brain development.

Once this period of time is added to supplement the thyroid hormone, brain developmental disorders can not be corrected (irreversible), so this limited time period is also called the critical period of brain development, and brain development is strictly coordinated in a certain order. Genomics is considered to be a "clock" that stops nerve cell proliferation and stimulates differentiation. During the critical period, thyroid hormone promotes the differentiation and migration of nerve cells, the development of neuronal microtubules, the extension of axons, and trees. Development of protruding branches and dendritic spines, development of synapses and establishment of neural connections, myelination of axons, synthesis of neuronal mediators (possibly affecting the synthesis of neuronal synthetases, enzymatic activity, metabolism of mediators) The development of certain specific neurons (choline, adrenergic and GABAergic nervous systems) are essential hormones.

Nunez noted that the decrease in synapse formation resulted in increased brain cell death and decreased brain cell number and volume during hypothyroidism. Patel believes that the key role of thyroid hormone in neuronal cell development is to promote its migration and differentiation, while neuronal The effect of proliferation is small. During the critical period, the expression of surface recognition factors in thyroid hormone-sensitive nerve cells is affected by thyroxine deficiency, various cells are not synchronized, and the spatial-temporal relationship between neurons is abnormal. , leading to abnormal nerve pathways or nerve cell stagnation, nerve cells die due to loss of mutual nutrient dominance, so brain cell abnormalities and wrong pathways are one of the mechanisms of irreversible damage caused by thyroid hormone deficiency in critical phase, the central nervous system is the most The fascinating feature is the complex and precise network connection between various neurons. It is the structural basis for accomplishing various behaviors. Modern psychology believes that the material basis of intellectual activity is the dendrites, dendritic spines, and processes in brain tissue. It is related to the level of development of neural connections.

Oppenheimer first confirmed that T3 binds to nuclear receptors and plays a role in hormones. T3 is the main active form of thyroid hormone. T3 on the nuclear receptors of surrounding tissues mainly comes from T3 in plasma. Larson found that brain cells and surrounding tissues have The difference is that the nuclear receptor-bound T3 is mainly derived from plasma T4, T4 enters brain cells, and after deiodinase (type II) is converted to T3, it binds to T3 receptor (T3R), and thyroid axis is deficient in iodine. The first to be affected is the decrease of T4, but T3 is normal. Therefore, the surrounding tissue is not affected by T3 normal. The decrease of T4 will directly affect brain development and brain function. Although the activity of type II deiodinase will be compensated in the absence of iodine. Increase, but long-term hypothyroidism, type II deiodinase compensatory failure, decreased enzyme activity, and even decreased brain T3R, so low T4 is directly related to brain development, and it is currently believed that the role of thyroid hormone is mediated through T3R. T3 and T3R combine to form a complex, T3R is activated, converted from non-DNA-binding to DNA-binding, and then interacts with or interacts with certain genes to transcribe or respond to specific genes. The synthesis of white matter plays a regulatory role, T4 decreases, affecting the transcription and translation of genes. T3R is a non-histone in the nucleus. The content of different nerve cells is different. The cerebral cortex, hippocampus and amygdala are the most abundant. Hypothalamus The thalamus, striatum, and olfactory bulb are the second; the cerebellum and brainstem are the least; while the T3R content in nerve cells is 2 to 3 times higher than that of glial cells, so the effect of thyroid hormone on nerve cells is through specific nuclear The receptor T3R exerts its biological effects.

Hypothyroidism caused by iodine deficiency is the basic pathogenesis of Dick disease. Hypothyroidism in different stages of embryonic development and infant development may be related to the pathogenesis of Dick disease.

(1) Fetal hypothyroidism: Fetal hypothyroidism is the main mechanism of brain development after the disease. At present, we can not obtain direct evidence from the development of human embryos to verify the fetal hypothyroidism caused by iodine deficiency. There are two evidences. It can indirectly indicate the presence of fetal hypothyroidism: one is found in aborted fetuses in severe iodine-deficient areas. Fetal hypothyroidism can occur as early as the fourth month of pregnancy, and hormonal hypothyroidism occurs earlier than goiter; another evidence It is the incidence of hypothyroidism in the severely ill areas of the fetus at birth is quite high, some as high as 10% to 30%, which was confirmed in Zaire, India, Tanzania and other wards, so far we do not know the neonatal hypothyroidism To what extent is the true reflection of fetal hypothyroidism, amniocentesis may be another way to find fetal hypothyroidism.

Animal experiments have confirmed that fetal hypothyroidism caused by iodine deficiency is the main cause of brain development. Potter removes fetal thyroid gland at different gestational times, and her newborn sheep show cretin-like changes. Early, the worsening of brain development, Potter fed ewes with low iodine feed, T4 decreased at 56 days, and goiter at 70 days. The brain development of the born lambs was very similar to that of the thyroid. That is, the wet weight of the brain is decreased; the DNA and protein content of the brain is decreased; the brain movement area, the density of the visual field and the hippocampus are increased, and the outer layer of the cerebellum is thickened, suggesting cell migration disorder; the Purkinje cell dendritic development disorder, the author has In the low-iodine rat model, fetal hypothyroidism is also the main mechanism of brain development. In the critical period, iodine supplementation or thyroid hormone supplementation can prevent its occurrence, which proves that fetal hypothyroidism is the main mechanism of brain developmental disorder.

(2) maternal hypothyroidism: maternal hypothyroidism is common in areas with iodine deficiency (especially in areas where visceral cretinism predominates). In Zaire, mother hypothyroidism and mucinous cretinism are unique. The specificity, therefore, Delange believes that maternal hypothyroidism is associated with fetal neurodevelopmental disorders, and it has been suggested that children born to mothers with low T4 have lower IQ than normal children, and to what extent mother's hypothyroidism affects fetal brain development. It is not clear that Potter mated the ewes after they had been removed. The examination of the sheep after pregnancy found that the early and middle gestational brain development was backward, but the brain development of the larvae did not differ from the control group at the late pregnancy and at birth. This result suggests that the mother's thyroid function is necessary to maintain fetal brain development, which is obvious in early pregnancy and has little effect in the third trimester, he also found.

Ewe and fetuses remove the thyroid at the same time. The brain development of the sheep is more serious than that of the low-iodine-born lambs. This also indicates the effect of maternal hypothyroidism on the fetus. Mano further confirmed that the low-iodine ewes model is in the second trimester. Injection of DIMIT (3,5-dimethyl-isopropyl-L-thymidine), which does not contain iodine but has thyroid hormone action, results in the correction of the yaw hypothyroidism, but the delivery of the still It shows the same serious brain development as the low iodine group (DIMIT can not pass the placenta), which indicates that the mother's hypothyroidism has little effect on the fetus. The above experimental results suggest that the mother's hypothyroidism only has a certain influence on fetal brain development in the early pregnancy. The mechanism may be T3 in the mother of early pregnancy, T4 can pass through the placenta, but not in the middle and late stages. Brain development at this time depends mainly on the thyroid function of the fetus itself. In fact, as Escobar proposed, before the fetal thyroid gland has function, T3R is already present in the fetal brain, so the mother's thyroid hormone may affect fetal brain development. In terms of pathogenesis, compared with the importance of fetal hypothyroidism, the mother's hypothyroidism Big is probably the most important mechanism grams of disease onset, the mother hypothyroidism may play a role in the following areas:

1 Before the formation of fetal thyroid function, due to maternal hypothyroidism, the amount of maternal T3, T4 into the fetus is insufficient.

2 When severe iodine deficiency, the mother's thyroid gland still has a good ability to take iodine. The developing fetal thyroid gland is at a disadvantage when competing with the mother to ingest the inorganic iodine of the mother's plasma, thus exacerbating fetal hypothyroidism and iodine deficiency.

3 pregnant women due to increased estrogen levels, liver thyroid hormone binding globulin increased, so that total plasma T3, total T4 increased, while FT3, FT4 decreased, the lack of iodine, this change will be more prominent.

4Coutras confirmed that during normal pregnancy, the iodine clearance rate of the kidney increased and the blood iodine decreased. The loss of endogenous iodine under this physiological condition, such as accompanied by insufficient iodine intake, would aggravate the iodine deficiency of the fetus.

5 During lactation, the mammary gland has the ability to concentrate iodine to ensure the iodine supply of infants and young children. The lactation of the mother during lactation will inevitably affect the supply of iodine to the baby through the milk. In the Zairian ward, it is found that the infant has hypothyroidism after weaning. .

(3) Neonatal hypothyroidism: In areas with normal iodine supply, the incidence of neonatal hypothyroidism is less than 0.02%, mostly sporadic cretinism, and the incidence of neonatal hypothyroidism in low-iodine areas is greatly increased in India. Up to 4% to 15%, Zaire 10% to 30%. In recent years, the number of neonatal TSH in the iodine concentration in the iodized salt is not higher than that in the non-patient area. Undoubtedly affecting brain development, within 2 years of life, is still the critical period of brain development, which is mainly the development of cerebellum, myelination, glial cell proliferation and the establishment of neuronal connections.

(4) transient hypothyroidism or subclinical hypothyroidism: these two hypothyroidism are found in low iodine wards, especially the slight increase in TSH, which also affects brain tissue and organ hypothyroidism, and may also It affects brain development or brain function to a certain extent.

2. The independent role of iodine: This is a controversial point of view. People who hold this view believe that the brain development of the fetus depends mainly on the thyroid function of the fetus itself. The thyroid function of the fetus is formed after 12 weeks of gestation. Brain development in the first 3 months of the fetus may be related to iodine, based on:

1 non-iodine deficiency factors cause congenital hypothyroidism in the fetus, such as sporadic cretinism, the clinical manifestations are significantly different from the disease, the symptoms of deafness and upper motor neuron damage in sporadic disease are not in sporadic cretinism Significant

2 mother throughout the pregnancy hypothyroidism (non-iodine deficiency reasons), the birth of the baby does not appear typical cretinism, or even completely normal;

The development of the 3Corti is between 10 and 18 weeks of gestation, just before the fetal thyroid is formed;

4Firro and Pharoach found that pre-pregnancy injection of iodized oil was more effective than mid-pregnancy injection to prevent the occurrence of Dick disease.

Recent studies, especially Escobar, have confirmed that mother T3, T4 can enter the fetus through the placenta before fetal thyroid formation. This finding changes the traditional view that mother T3, T4 cannot pass through the placenta; but after the fetus forms the thyroid gland, This permeability has declined. According to recent research, fertilized eggs begin to receive maternal thyroid hormone supply on the third day after implantation, so the fetus depends mainly on the mother's T3 and T4 before thyroid function is formed, even if After the formation of fetal thyroid function, the mother's T3 and T4 are still accepted. It is found that 10% of the thyroid hormones in the fetus are born from the mother. Animal experiments also confirm that the development of the inner ear is also dependent on thyroid hormone instead of iodine. Therefore, Hetzel pointed out "There is no evidence that iodine has a direct effect on brain development."

Therefore, it is generally believed that the lack of thyroid hormone synthesis during the critical period of brain development is the main pathogenesis of Dick disease.

Subclinical cretinism prevention

Because of its mild clinical retardation, ykting disease belongs to the mental retardation with structural abnormalities. The so-called structural abnormality means that this mental retardation has certain pathological changes, structural abnormalities and nervous system damage. The pathogenesis of this disease is the same as that of Dick disease. Mild damage caused by mild iodine deficiency or iodine deficiency is the basic link of its disease. It is worth noting that in recent years, the concentration of iodized salt is unstable or unqualified and non- Iodized salt enters the ward, the correction of iodine deficiency in the population is not complete. Although the thyroid swollen and the gram disease have been basically controlled, the key population, especially the iodine deficiency in pregnant women, is an important cause of acquitine. The incidence of ting disease is much higher than that of typical cretinism, and it seriously affects the quality of the population and hinders the development of social economy. Therefore, the intelligence level of the ward population is becoming an important indicator to measure the quality of iodine deficiency disorders. Controversy about its diagnosis, it is better to focus on the prevention and treatment of this disease, strict salt iodization or women of childbearing age to strengthen iodine (oral oil or intramuscular injection) is the main hand to prevent and treat this disease .

1. First level prevention:

(1) Iodized salt is a simple and effective way to prevent and treat iodine deficiency disorders. The ratio of salt to iodization is 1:50,000, which can effectively prevent the disease of the nail; 1:2 million can prevent the disease, join Potassium iodide in salt is easily oxidized and sublimated. Since 1993, it has been changed to potassium iodate with good stability. During the process of packaging, storage, transportation and consumption of iodized salt, it is necessary to keep the iodized salt dry and the package is tight and airtight. According to the measurement, the iodine loss rate of iodized salt after half a year of different storage methods: 10% in the cylinder; 29.4% in the sack; 57.8% in the drawer; 1.9% loss in boiling 2h; 66.1% loss in baking 2h.

(2) Iodized oil injection or oral administration, iodized oil is a long-acting, economical, convenient, and small side-effect prevention and treatment drug, especially suitable for remote, inconvenient transportation, soil and salt interference areas, especially for women of childbearing age, iodization After oil injection, the iodine supply efficiency can reach 3 to 5 years. The oral iodized oil method is simple, the mass is easy to accept, and the control effect is also obvious. The iodine supply efficiency is generally about one and a half years.

(3) Guarantee the amount of iodine required by the human body:

1 group <4 years old normal range 30 ~ 105g / d; suitable amount 70g / d.

2 4 years old and normal range of 75 ~ 225g / d; suitable amount of 150g / d.

3 pregnant women, the normal range of lactating mother 150 ~ 300g / d; suitable amount of 200g / d.

(4) Women of childbearing age during pregnancy can prevent iodine deficiency during embryonic period (cretinism, subclinical cretinism, neonatal hypothyroidism, neonatal hyperthyroidism and premature birth, stillbirth, congenital malformation).

2. Second level prevention:

(1) Monitoring of iodine prevention and treatment:

1 Iodine salt containing iodine monitoring: including iodized salt iodine concentration, packaging, factory sampling, storage and storage, sales points and households in the spot checks, timely correction of problems, reduce iodine losses.

2 Iodized oil injection and oral monitoring: to prevent complications.

3 Disease monitoring: The monitoring point regularly surveys and compares the dynamic changes of the incidence of goiter in the population before and after consumption of iodized salt.

4 iodine metabolism and functional status of pituitary thyroid system, urine iodine determination: urinary iodine increased after iodine addition, group urine iodine determination is meaningful, when urinary iodine <25g / g creatinine, is the criticality of endemic goiter complicated with cretinism Concentration; 131I rate of thyroid uptake (24h) was lower than that before iodine; serum T3, T4: increased with iodine; serum TSH: lower than before iodine supplementation.

5 Determination of children's IQ: no less than 70.

(2) Diagnostic criteria for endemic goiter (1978 China Conference on Prevention and Treatment of Endemic Goiter):

1 living in the goiter area.

2 The thyroid enlargement exceeds the distal end of the thumb or has nodules smaller than the distal end of the thumb.

3 exclude hyperthyroidism, thyroid cancer and other thyroid diseases.

4 ward division criteria (in rural areas).

Lightly ill areas: the prevalence of goiter in residents is >3%; the rate of goiter in primary and middle school students aged 7 to 14 is >20%; urinary iodine is 25-50 g/g creatinine.

Intensive care area: the prevalence of goiter in residents is >10%; the rate of goiter in primary and middle school students aged 7-14 years is >50%; urinary iodine <25g/g creatinine.

(3) Diagnostic criteria for endemic cretinism (developed in 1980):

Prerequisites:

1 born, living in areas of low-iodine endemic goiter;

2 have mental retardation, mainly manifested in varying degrees of mental retardation.

Auxiliary conditions:

1 have varying degrees of hearing, language and motor neurological disorders;

2 hypothyroidism, there are different degrees of physical developmental disorders, cretinism image (stupid phase, wide face, wide eye distance, collapsed nose, abdominal bulging, etc.);

3 different degrees of hypothyroidism (mucus edema, dry skin, delayed X-ray and delayed healing of the epiphysis, decreased plasma PBI, elevated serum T4, TSH).

Anyone with one or more of the necessary and auxiliary conditions and who can rule out birth injury, encephalitis, meningitis and drug poisoning can be diagnosed with Dick disease.

3. Third level prevention:

Thyroid powder preparation therapy: It has extremely obvious effect on the treatment of patients with gelatinous goiter. Adults take oral thyroid tablets 60-120mg per day, combined with potassium iodide 10mg, 3 months for one course of treatment, generally 2 to 4 courses, treatment interval For half a month, the curative goiter and cystic hypertrophic nodular goiter are better.

Subclinical cretin complication Complications, mental retardation

Mild mental retardation, mild nerve damage, affecting brain development and physical development.

Subclinical cretinism symptoms Common symptoms Craniofacial deformity Iodine deficiency Fatigue gait instability Slow thyroid dysfunction Mental retardation Deafness Meningitis Reflex hyperactivity

1. Mild mental retardation: In terms of mental retardation, IQ (IQ) less than 54 can be diagnosed as Dick disease; IQ is 55 to 69 is mild mild retardation (MMR), the so-called mental retardation, which is The main characteristics of Aktin In 1966, Firro used the Stanford-Binet scale to examine "normal" children in the iodine-deficient area of Ecuador, and found that 35.4% were MMR, compared with 3.2% in the control group. Mehta confirmed in India MMR is about 20%. Wang Dong, Chen Zupei et al. used the Chinese internal test and Raven test method to confirm that the ratio of MMR is about 5% to 20%, and that of some severe iodine-deficient areas can reach 30%. These results reflect the MMR. Existence, its incidence is much higher than the incidence of Dick disease (generally <5%, most of which is below 2% =, MMR children often show poor computational ability; memory, especially long-term memory ability; abstract computing power Poor; attention, cognition and comprehension are lower than normal children, and some are accompanied by certain emotional disorders. In recent years, Meta Analysis (meta-analysis) has been conducted on intelligence investigation reports. The results show that iodine deficiency can lead to the average IQ of the population. Lost 12.45 percentage points, this Real sufficient to show serious impact of iodine deficiency on brain development and human qualities, after the implementation of salt iodization of children born after Meta Analysis found that IQ can be increased 11.1 percentage points.

2. Mild nerve damage: The nerve damage of Aktin's disease is light, and it is often necessary to use a fine inspection method to detect it.

(1) psychomotor defects: skills have motor skills and intellectual skills, the former is the explicit skeletal muscle activity, the latter is the internal thinking activity, when completing more complex or finer movements or activities, two All kinds of skills work, that is, the so-called hands and brains. The motor function test items designed by this principle can often reflect the mild damage related to intelligent development, such as: grip strength, tapping, reaction, motion accuracy, action. Fatigue and other tests, Aktin patients often perform abnormally, such as prolonged reaction, fatigue, and poor accuracy. If the test is tested by a complete set of methods, it can reflect the low score of ictinosis, showing abnormalities of neuromotor function, some of which are more serious. Children with ykting disease seem normal, but when running, they can find gait instability and poor movement accuracy. For preschool children, especially infants and young children, you can check the development of neuromotor function to judge abnormalities. Or calculate the developmental quotient (DQ) to assess the developmental status of children. The most commonly used in China is the DDST scale (Danvers development screening test). In 1984, Wang Dong used the DDST scale to screen out dysplastic and suspicious infants in three villages in Hequ County, Shanxi Province. This abnormal proportion is related to the degree of iodine deficiency.

(2) Mild hearing impairment: patients often do not show deafness, but have different levels of hearing impairment. In severe children, they can only sit in the front row during class to hear the teacher's lecture. Pretell reports that the incidence rate is 11 %, Wang Yanxi found in Guizhou, 23.3% of normal children had an average hearing threshold (>23dB), which was significantly higher than the control group (7.5dB). In addition, MMR patients were more likely to have mild hearing impairment.

(3) Other positive findings: Some patients were accompanied by pyramidal tract reflexes, Babinski's disease positive and other pyramidal tract symptoms, and some EEG found slow wave increase (, wave), most auditory evoked potential abnormalities, There are also visual evoked potential abnormalities.

3. A small number of patients with hormonal hypothyroidism showed a decrease in T4 and an increase in TSH, but most people showed normal T3, slightly lower T4 (can be in the normal range), subclinical hypothyroidism such as elevated TSH, and only TSH. High indicates that the brain and pituitary have some degree of organ hypothyroidism, so it will affect brain development or physical development to a certain extent, so Aktin patients can be expressed as height, weight, head circumference is lower than normal, bone age Poor healing or poor healing of the epiphysis is often a sensitive indicator of the detection of ictinosis.

Subclinical cretinism

1. Determination of thyroid hormone: The increase or decrease of TT4 is mainly related to the amount of thyroid secretin (hyperthyroidism or hypothyroidism), and secondly to the level of TBG in blood and its affinity with thyroxine and whether there is abnormality. Binding to proteins.

TT4 reduces the reduction in thyroid hormone synthesis and secretion caused by various causes, including primary and secondary hypothyroidism.

2. Determination of thyroid stimulating hormone (TSH): Determination of TPOAb can increase autoimmune subclinical hypothyroidism when TSH is elevated. The higher the TPOAb titer, the faster the progression to hypothyroidism.

3. Bone age test: suggesting that there is bone age development and poor healing of the callus.

4. EEG examination: visual evoked potential abnormalities may occur, and auditory evoked potential abnormalities may occur.

Diagnosis and diagnosis of subclinical cretinism

diagnosis

The diagnostic criteria developed by the Health Standards Committee and issued by the Ministry of Health are as follows:

1. Diagnostic principle: Those who have the following necessary conditions and have one or more of the auxiliary conditions can be diagnosed as Dick or Yak separately after excluding the diseases caused by iodine deficiency. Ting.

2. Diagnostic criteria:

(1) Prerequisites:

1 Epidemiology: Patients must be born and live in an iodine deficiency ward.

2 clinical manifestations: there are varying degrees of mental retardation, mainly manifested in varying degrees of mental retardation (lower), IQ (IQ) of Aceting disease is 55 to 69, IQ of Dick disease is below 54 (including 54) .

(2) Auxiliary conditions:

1 Nervous system disorders: motor neurological disorders (cone system and extrapyramidal system), including varying degrees of spastic paralysis, gait and posture abnormalities, Dick patients showed obvious, and these typical clinical signs did not exist in Aktin patients. However, there may be mild nervous system damage, manifested as psychomotor disorders and/or motor skills disorders, and Dick's disease may have hearing impairment; Aktin may have extremely mild hearing impairments, such as hearing thresholds when using electrical audiometry. Raised, high frequency or low frequency is abnormal.

Dick disease has speech disorders (dumb or speech disorder); akectin is extremely mild speech disorder or normal.

2 thyroid dysfunction: Dick disease has physical developmental disorders; akectine may have no or mild physical developmental disorders.

Dick disease has the following different degrees of cretinism (the appearance of mental retardation), such as: stupid, smirk, wide eye distance, nasal bridge collapse, soft ear, abdominal bulging, umbilical hernia, etc.; Performance, but the degree of development of the bone age can be different and the healing of the epiphysis is poor.

Dick disease often has clinical thyroid dysfunction (hypothyroidism), such as mucinous edema, dry skin, dry hair; serum T3 is normal, compensatory increase or decrease, T4, FT4 is lower than normal, TSH is higher than normal; Acetin generally has no clinical low performance, but may have hormonal hypothyroidism, that is, serum T3 is normal, T4, FT4 normal lower limit or lower, TSH may be increased or above the normal upper limit.

3. Diagnostic considerations:

(1) When diagnosing Dick disease, attention should be paid to the exclusion of birth injury, neonatal asphyxia, encephalitis, meningitis, epilepsy, drug poisoning, etc. caused by mental retardation caused by brain damage; otitis media, drugs (such as streptomycin, Qing Hearing or speech disorder caused by cerulein, so when the patient has the above-mentioned necessary conditions, but can not rule out other diseases that cause similar symptoms of the disease, it should be considered as a suspicious patient with Dick disease, to be further diagnosed.

(2) When diagnosing icytin, other causes should be excluded, such as malnutrition, zinc deficiency, and cultural background may affect intelligence; otitis media or other drugs that damage the auditory nerve may affect hearing; and factors affecting bone age and physical development. You should exclude them one by one to diagnose ictin.

(3) The diagnosis of mental retardation can be based on the intelligence test method. Those who are 5 years old or older (including 5 years old) are recommended to use the Chinese Raven test; 4 years old (including 4 years old) are recommended to use the Chinese Denver Development Screening Scale or other Develop a scale of developmental quotient (DQ).

(4) For the diagnosis of psychomotor disorders or motor skills disorders, it is recommended to use multiple measures of comprehensive assessment or use the complete mental exercise test scale.

Note: The IQ rating is based on the Raven and Wechsler tests (=100, s=15).

Differential diagnosis

In the epidemic area of the genital area, it is not difficult to diagnose sputum, dumb, dementia, neuromotor dysfunction, and poorly developed physiology. The difficulty in identification is mainly the dysplasia with no thyroid or hypothyroidism. How to distinguish patients with other mental retardation and deaf-mute patients (not caused by iodine deficiency).

1. Sporadic cretinism: These patients have very prominent mucinous edema and other hypothyroidism symptoms, mental retardation, delayed ossification center, but generally no obvious hoarseness, thyroid iodine absorption rate is almost zero, almost no obvious Muscular dyskinesia, thyroid nucleus shows thyroid deficiency or ectopic, and generally no symptoms of pyramidal tract damage, these can be identified.

2. The sequelae of brain damage caused by acquired factors: such as birth injury, encephalitis, meningitis, brain trauma, poisoning factors, etc., their identification mainly depends on detailed medical history, and those with a clear history can be excluded from the diagnosis of gram disease.

3. Congenital type (Down syndrome): This patient has no hoarseness, no hypothyroidism, often has small ear deformity, small finger deformity and traversal hand, chromosome examination can be clearly diagnosed, that is, 21 trisomy, so easy to identify .

4. Pendred syndrome: The syndrome has obvious goiter and congenital deafness, but there is no hypothyroidism, no mental retardation, and physical development is normal.

5. Pituitary pygmy: The patient showed symmetry, proportional body short, normal intelligence, hearing and language barrier-free, normal thyroid function, which can be identified with Dick disease.

6.Laruence-Moon-Biedl syndrome: a rare autosomal recessive hereditary, with low mental retardation and sexual organ dysplasia, but the following three symptoms are unique to this syndrome and can be distinguished from Dick disease: obesity, more Finger (toe) or finger (toe) malformation and retinitis pigmentosa.

7. Phenylketonuria: a common autosomal recessive disorder with symptoms within 4 to 6 months after birth, yellow (yellow hair), white (skin white), stupid (intellectually low), stinky (Beat and smell have odor) and other four characteristics, urine iron oxide test is positive, blood phenylalanine concentration increased.

8. Mucopolysaccharidosis (constrained by slip): autosomal recessive inheritance, short stature, developmental delay, mental, hearing and language barriers. The point of differentiation is that the disease has hepatosplenomegaly and the fingers are curved. "Special face: such as: ugly, nose lifted, nostril upturned, the lower edge of both ears is lower than the binocular level, the tongue is large and thick, the neck is short, the rib X-ray film is ribbon-like, the spine is tongue-like, urine Mucopolysaccharide is positive, and most children die around 10 years old.

9. Galactose hematuria: autosomal recessive inheritance, feeding difficulties or refusal to eat weeks to months after birth, mental retardation, liver, cataract, urine mucic acid test positive.

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