Causes of hypothyroidism
First, congenital reasons:
1, thyroid hypoplasia or hypoplasia will lead to hypothyroidism;
2. Due to congenital defects, lack of some enzymes for synthesizing thyroid hormone leads to disorder of thyroid hormone synthesis and hypothyroidism;
3. When the defect of thyroid hormone receptor in tissue is caused by congenital reasons, even if the amount of thyroid hormone is not available, thyroid hormone will not work due to the defect of receptor, resulting in hypothyroidism.
Second, the day after tomorrow:
1, long-term dietary iodine deficiency leads to insufficient raw materials for thyroid hormone synthesis, and decreased thyroid hormone production leads to hypothyroidism;
2. After surgical treatment, hypothyroidism may occur due to complete or excessive thyroidectomy; The destruction of thyroid tissue caused by various thyroiditis may cause hypothyroidism; In some patients, drugs can inhibit the production of thyroid hormones and cause hypothyroidism;
3. hypothalamus? Due to the lack of thyroid stimulating hormone in pituitary lesions, the function of thyroid gland to produce thyroid hormone is reduced, which will also lead to hypothyroidism.
Harm of hypothyroidism
The harm of hypothyroidism should not be underestimated, as shown in the following figure:
1 and hypothyroidism will affect growth and development.
Children suffering from hypothyroidism can lead to mental retardation and even dementia, short stature and so on. Thyroid hormone can promote growth hormone, and the lack of thyroid hormone will affect the growth-promoting effect of growth hormone. Children with hypothyroidism often show slow growth, slow epiphysis healing and delayed bone age. Teenagers with hypothyroidism show developmental retardation, and a few show precocious puberty.
2, hypothyroidism will affect sexual ability and fertility.
After suffering from hypothyroidism, female patients are characterized by excessive menstrual flow, prolonged menstrual period and even amenorrhea, which makes it difficult to conceive. Even if the pregnancy is successful, the probability of miscarriage, stillbirth and congenital hypothyroidism after birth is very high. For men, it is characterized by decreased sexual desire, breast development, impotence and fertility difficulties. Moreover, hypothyroidism is hereditary, and the offspring of hypothyroidism patients are also very likely to suffer from hypothyroidism. Therefore, if you have hypothyroidism, the doctor will advise you to have children after you are cured.
3, hypothyroidism will affect the cardiovascular system.
When thyroid hormone is low, physical examination shows that the patient's heartbeat is slow and weak, heart sounds are dull, the heart is enlarged, bradycardia, edema of lower limbs, blood pressure is increased and pulse pressure difference is decreased. Pseudohypertrophy of myocardium, ECG low voltage, sinus bradycardia. About 30% patients have pericardial effusion, and in severe cases, there will be pleural or peritoneal effusion.
4, hypothyroidism will affect muscle joints.
The clinical manifestations of hypothyroidism patients are fatigue, muscle pain, rigidity, spasm, edema, hypertrophy, elevated serum CPK, LDH and AST, and isoenzymes mainly come from striated muscles. The relaxation period of Achilles tendon reflex in hypothyroidism patients is obviously prolonged, but it is not sensitive enough.
5, hypothyroidism will affect the gastrointestinal system.
The smooth muscle tension of esophagus, stomach, gallbladder, small intestine and colon is weakened, gastrointestinal peristalsis is slow, emptying time is prolonged, gastric acid secretion is reduced, and serum anti-gastric parietal cell antibody is positive. The patient showed anorexia, abdominal distension, nausea, low gastric acid and difficulty in defecation.
Treatment of hypothyroidism
First, symptomatic treatment.
People with anemia should be supplemented with special drugs, such as vitamin B 12 and folic acid. And those with low gastric acid should be supplemented with dilute hydrochloric acid, but it must be combined with thyroxine to achieve the curative effect.
Second, alternative therapy.
No matter what kind of hypothyroidism, thyroid hormone replacement therapy is needed to maintain normal thyroid function, and generally lifelong replacement is needed. A few Hashimoto thyroiditis also reported spontaneous remission. The selection, initial dose and optimal maintenance dose of thyroxine preparation should be individualized according to specific cases. Commonly used preparation: levothyroxine (L-T4), with a half-life of 7 days and lasting and stable action, is the first choice. Initial dose 25~50? G/ day, the adult maintenance dose is mostly 50-200ug/ day.
The half-life of levothyroxine is 7 days, and about 80% is absorbed after oral administration. After about 6 weeks, the blood concentration can reach equilibrium. The initial dose of levothyroxine is 25ug/ day, and then the dose is increased every one to two weeks until the maintenance dose is reached. The index of achieving maintenance dose is the improvement of clinical symptoms, and T3, T4 and TSH are normal. Pregnant women should control TSH below 2.5mU/L and FT4 at the upper limit of normal range. Children need higher doses, while elderly patients need lower doses. For the elderly or those with a history of coronary heart disease, the initial dose should be small and gradually increased to prevent the induction and aggravation of myocardial ischemia.
Patients with thyroid cancer need a relatively large replacement dose, about 2.2ug/kg/ day, and high-risk patients should control TSH at the level needed to prevent tumor recurrence (0. 1 mU/L or lower). For patients with subclinical hypothyroidism, it is generally believed that replacement therapy is needed when TSH is greater than 65438+1100mu/L. Patients with TSH between 4-65438+ 100mu/L and positive TPOAb can be closely followed up and given thyroid hormone replacement therapy if necessary. The treatment of patients with central hypothyroidism should aim at reaching half of the normal range of T4 and FT4, instead of TSH.
Thyroid tablet is a dry preparation of animal thyroid. Because of its unstable thyroid hormone (T3 and T4) content and high T3 content, it is rarely used for routine replacement therapy of hypothyroidism.