What Is Congenital Hypothyroidism?

The main function of the thyroid is to synthesize thyroxine (T4) and triiodothyronine (T3). The main raw materials of thyroid hormone are iodine and tyrosine. After iodine ions are taken into thyroid epithelial cells, they are combined with tyrosine through a series of enzymes.

Congenital hypothyroidism

Congenital hypothyroidism is caused by congenital thyroid deficiency or iodine deficiency in the mother's diet during pregnancy. The former is called sporadic hypothyroidism and the latter is called endemic hypothyroidism. Its main clinical manifestations are physical and intellectual developmental disorders. Is a common endocrine disease in children.

Causes and pathogenesis of congenital hypothyroidism

The synthesis and release of thyroxine are controlled by the hypothalamus secreted by thyroid stimulating hormone (TRH) and pituitary secretion of thyroid stimulating hormone (TSH). T4 in serum can reduce the response of pituitary to TRH through negative feedback and reduce secretion.

Thyroxine accelerates the intracellular oxidation process; promotes metabolism; promotes protein synthesis and increases enzyme activity; promotes sugar absorption and utilization; accelerates lipolysis and oxidation; promotes the anabolic metabolism of calcium and phosphorus in bone; promotes the growth and development of the central nervous system .

When the thyroid function is insufficient, it can cause metabolic disorders, low physiological functions, retarded growth and development, and mental retardation.

The main cause of congenital hypothyroidism is hypothyroidism or hypoplasia, which may be related to the presence of immunoglobulins that inhibit the growth of thyroid cells in the body; followed by enzyme defects in the thyroxine synthesis pathway (autosomal recessive genetic disease); Thyroid hormone deficiency and rare thyroid or target organ response are rare. At present, secondary infections cause an increase in hypothyroidism.

Clinical manifestations of congenital hypothyroidism

Clinical manifestations

Congenital hypothyroidism symptoms in the neonatal period

Most children with congenital hypothyroidism are asymptomatic at birth, because maternal thyroid hormone (T4) can pass through the placenta to maintain 25% to 75% of the normal T4 concentration at birth. The occurrence and severity of this symptom in the neonatal period are related to the intensity and duration of hypothyroidism. About 1/3 of the children are born with great gestational age, large head circumference, cardia, and cranial suture. Hypothermia, low heart rate, little crying, less movement,

Children with congenital hypothyroidism Difficult feeding, vomiting and choking, excessive sleep, apathy, hoarseness, delayed fetal discharge, refractory constipation, prolonged physical jaundice, no weight gain or slow growth, large abdomen, umbilical hernia, decreased muscle tone . Due to poor perfusion of surrounding tissues, the limbs are cold, pale, and often patterned. The forehead has many wrinkles, looks like an old man, the face is swollen, the nose is flat, the eye distance is wide, the eyelids are thick, the eyelids are small, the hair is dry, the hairline is low, the lips are thick, and the tongue is large. They often stick out of the mouth. Difficulty breathing.

Typical manifestations of children with congenital hypothyroidism

(1) Special facial features include nose slumping, wide eye distance, thick tongue, often sticking out of the mouth, dull expression, swollen face, rough skin, dryness and anemia. She has a pale complexion, thickened nose and lips, thinning hair, crisp, and shedding eyebrows.

(2) mental retardation, sluggish neural reflexes, slow speech, unclear pronunciation, low-dumb voice, and more sleep and movement. Faint expression, dull vision, hearing, smell and taste. There are hallucinations, delusions, depression, stiffness, lethargy, and severe cases can be mental disorders.

(3) Lack of growth and development, backward bone age, short stature, short limbs, upper body volume is greater than lower body volume, slow movement, walking posture like duck steps. Tooth hypoplasia. Sexual retardation and delayed puberty.

(4) May have constipation, myxedema all over the body, enlarged heart, and pericardial effusion.

(5) May have bone pain, muscle soreness, muscle tension

People with endemic hypothyroidism cannot synthesize sufficient thyroid hormones due to iodine deficiency during the fetal period, which seriously affects the development of the central nervous system. There are two clinical manifestations. One is mainly neurological symptoms, ataxia, spastic paralysis, deafness, and mental retardation, while other manifestations of hypothyroidism are not obvious. The other is mainly myxedema, with special face and posture, mental retardation and nervous system

Congenital hypothyroidism ^[1] Check normal.

Laboratory tests for congenital hypothyroidism

Due to the high incidence of congenital hypothyroidism, severe damage to the nervous system function early in life, and its easy treatment and good curative effect, early diagnosis and early treatment are very important.

1. Newborn screening The "Maternal and Child Health Law" promulgated in June 1995 in China has included this disease as one of the screening diseases. At present, more than 2 to 3 days after birth, the dry blood drip paper of newborns is used to detect TSH concentration as the initial screening. When the result is greater than 20mU / L, the serum T4 and TSH are detected to confirm the diagnosis. The method of collecting specimens is simple and the false-positive and false-negative rates are low, so it is an excellent prevention and treatment measure for early diagnosis of children, avoiding severe neuropsychiatric defects, and reducing the burden on the family and the country.

2. Serum T4, T3, and TSH determination Any child with a neonatal screening result or a clinically suspicious child should be tested for serum T4 and TSH concentrations. If the T4 decreases and the TSH significantly increases, the diagnosis can be confirmed. Serum T3 concentration can be reduced or normal.

3 If the serum T4 and TSH are low in the TRH stimulation test, it is suspected that the secretion of TRH and TSH is insufficient, and a further TRH stimulation test should be performed: intravenous injection

Congenital hypothyroidism mechanism TRH7ug / kg, the normal person showed TSH peak within 20-30 minutes after injection, and returned to the basic value after 90 minutes. If there is no peak, pituitary lesions should be considered; if the TSH peak appears longer, hypothalamic lesions are suggested.

4 X-ray examination of the left hand and wrist X-rays to assess the bone age of children. The bone age of children often lags significantly behind the actual age.

5. Radionuclide examination was performed with single photon emission computed tomography (SPECT) after intravenous injection of 99m_Tc to detect the thyroid development and the size, shape and location of the thyroid.

Diagnosis and differential diagnosis of congenital hypothyroidism

Based on typical clinical symptoms and thyroid function tests, diagnosis is not difficult. However, it is not easy to confirm the diagnosis in the neonatal period, and the newborn should be screened. Older children should be distinguished from:

1. Children with congenital megacolon begin to have constipation, abdominal distension, and umbilical hernia often after birth, but their faces, mental reactions, and crying are all normal. Barium enema shows colonic spasm and expansion.

2.21- Children with trisomy syndrome have retarded intelligence and movement, but have special faces: wide eye distance, oblique outer corner, low nose bridge, tongue sticking out of the mouth, normal skin and hair, no myxedema, often accompanied by There are other congenital malformations. Karyotype analysis can be identified.

3 Children with rickets have signs of stunted movement and delayed growth. But the intelligence is normal, the skin is normal, there are signs of rickets, blood biochemistry and X-rays can be identified.

4 Skeletal development disorders such as osteochondral dysplasia, mucopolysaccharidosis, etc. all have symptoms of growth retardation, and bone X-rays and urine metabolites can be identified.

Treatment of Congenital Hypothyroidism

Treatment of fetal hypothyroidism with congenital hypothyroidism

Due to the rapid turnover of amniotic fluid, and T3 and T4 are easily absorbed by the fetus, it is feasible to treat the suspected congenital hypothyroidism fetus during prenatal examination by injecting T4 or T3 into the amniotic cavity for treatment, or directly injecting and decreasing fetuses and injecting thyroid hormone. Na-L-T4500 g was injected after 32 weeks after school, once every 2 weeks or 120 g once a week.

Thyroxine replacement therapy for congenital hypothyroidism

Once the addition or subtraction is confirmed, the combination of Chinese and western medicine should be started immediately. The sooner the treatment is, the more beneficial it is to brain development, and a full course of treatment is required, even if pregnant. After the start of treatment, blood thyroid hormones and TSH should be reviewed regularly. Start to check once a week. After the blood hormone concentration reaches the normal range, check again every 3 months. After the condition is stable, check again every 6 months to 1 year. Every year, ten thousand X-rays must be examined to observe the development of bone age. In the course of treatment, pay attention to observe the child's mental condition. Generally, after 2 to 3 weeks of traditional Chinese medicine treatment, appetite increase, language and activity increase.

Incidence of congenital hypothyroidism More, improved constipation, increased urine output. After a period of treatment, some children must rule out the possibility of temporary hypothyroidism. Generally, after continuous medication for 1 to several months, the drug is temporarily discontinued to observe the changes in T3, T4, and TSH. If T4, TSH is at normal levels, it is Temporary hypothyroidism can be discontinued. If T4 is low and TSH is high, it is permanent hypothyroidism and treatment should be continued. People with thyroid dysplasia need longer treatment. During the treatment process, due to the rapid growth and development of the child, timely supplementation of nutrients and multivitamins, such as calcium tablets, iron, vitamins B, C, A, D, etc., especially B vitamins. Hypothyroidism caused by familial enzyme deficiency should also be supplemented with iodine. The prognosis of congenital addition and subtraction is closely related to the age at which treatment is started. The earlier the diagnosis, the earlier the treatment, and the better the prognosis. If treated 3 months after birth, 74% of cases have an IQ of 90 or more. For patients treated 4 to 6 months after birth, 33% have an IQ of 90 or above, but about 15% of patients can leave irreversible sequelae of brain injury, which may be related to the following factors: the type of addition and subtraction, the time of onset and duration The time, especially the T4 concentration and bone age at the time of diagnosis, were lower in uterine hypothyroidism. The most important thing is that whenever a hypothyroidism is found, it should be treated with Chinese medicine in time. The disease should be diagnosed early and treated as early as possible to reduce damage to brain development. Once the diagnosis is established, the thyroid preparation should be taken for life without interruption, otherwise the previous work will be abandoned. The diet should be rich in protein, vitamins and minerals.

Congenital hypothyroidism thyroid preparation

There are two types of thyroid preparations,

L-thyroxine sodium: 100ug or 50ug / tablet, containing T4, half-life is one week, only a small change in T4 concentration daily, the serum concentration is stable, once a day can be taken. The dosage is 8-14ug / kg for infants and 4ug / kg for children.

Dried thyroid tablets: 40mg / tablet, which is extracted from animals and contains T3 and T4. If taken for a long time, T3 can be increased.

Inhibition of congenital hypothyroidism Pay attention.

60mg of dry thyroid tablets is equivalent to 100ug of L-thyroxine sodium. The starting amount should be from small to large, and the dose should be increased once every 1 to 2 weeks until the clinical symptoms improve and the serum T4 and TSH are normal, that is, used as a maintenance amount. Too little medicine will affect intelligence and physical development.

Dosage for congenital hypothyroidism

The dosage can be appropriately adjusted according to thyroid function and clinical manifestations. TSH concentration should be normal, blood T4 should be normal or high, in order to convert some T4 to T3; Clinical manifestations: normal stool once a day, appetite improved, abdominal distension disappear The heart rate is maintained at 110 times for children and 140 times for infants. Drug overdose can cause irritability, sweating, weight loss, abdominal pain, diarrhea, fever and so on. Therefore, follow-up should be paid attention to during the treatment. At the beginning of treatment, follow-up visits every 2 weeks; once serum TSH and T4 are normal, once every 3 months; after taking the medicine 1 to 2 noon, once every 6 months. During the follow-up process, pay attention to observe the growth and development and serum T4, TSH concentration, and adjust the dose at any time.

If the treatment is started within 3 months after birth, the prognosis is better, and most of the intelligence can reach normal; if the diagnosis is not early, and the treatment is started after 6 months, although the administration of thyroxine can improve the growth condition, the intelligence is still Could be severely damaged.

Nursing measures for congenital hypothyroidism

1. Keep children warm and prevent infections due to low basal metabolism and low activity due to low body temperature and fear of cold. Because the body's resistance is low, it is susceptible to infectious diseases. Pay attention to the indoor temperature, add or remove clothes in time to avoid cold. Bathe regularly to prevent skin infections. Avoid contact with children with infectious or infectious diseases.

2. Ensure nutritional supply to inform parents of the condition and guide feeding methods. Patients who have difficulty sucking and who swallow slowly should be patiently fed, provide sufficient meal time, and use a dropper to feed milk or nasal feeding if necessary. After the treatment of the cause, the child's metabolism is enhanced and the growth and development are accelerated. Therefore, it is necessary to provide high-protein, high-vitamin, calcium-rich and iron-rich digestible food to ensure the growth and development needs.

3 Explain the necessary measures to prevent and treat constipation to parents, such as providing sufficient fluid intake for children; drinking 1 cup of hot water half an hour before breakfast can stimulate bowel movements; massaging the abdomen several times per day with the direction of bowel movements to increase bowel Peristalsis; properly guide children to increase activity and promote

Protection against congenital hypothyroidism ^[2] Intestinal peristalsis; develop regular bowel habits and use stool softeners, laxatives, or enemas if necessary.

4. Strengthen training, promote growth and development, and do well in daily life care. Children with poor intellectual development and lack of self-care ability. Teach children and parents about the disease to gain cooperation and increase confidence in fighting it. Strengthen daily care for children to prevent accidental injuries. Strengthen intelligence through various methods. Physical training to promote growth and development and enable them to master basic life skills. Encourage children and not discriminate.

5. Insist on taking medication for life, pay attention to observe the reaction of the medication to guide parents and children, make them understand the necessity of lifelong medication, and adhere to medication. For those who started treatment late, although their intelligence cannot be improved, they can become lively and improve the symptoms of low physiological function. The effect of thyroid preparations is slow, and the best effect is achieved after 1 week of medication. Therefore, the appetite, activity and defecation of children should be closely monitored after taking the medication, and body temperature, pulse, weight and height should be measured regularly. Dosage increased with the age of children. Small doses are not effective, too much can cause hyperthyroidism, consume more, cause negative nitrogen balance, and promote bones to mature too quickly, causing growth disorders. When side effects of the drug occur, those with mild fever, sweating, weight loss, and increased nerve excitability. Severe vomiting, diarrhea, dehydration, high fever, pulse rate, and even spasms and heart failure. At this time, you should report immediately and reduce the dose as appropriate, and give first aid care such as fever reduction, sedation, oxygen supply, and heart function protection.

6. Pay attention to newborn screening. This disease has the highest incidence of genetic and metabolic diseases. Once diagnosed early, treatment can be started 1 to 2 months after birth to avoid damage to the residual nervous system function.